* Re: [PATCH v3 0/4] mm: improve large folio readahead and alignment for exec memory
From: Lorenzo Stoakes @ 2026-04-10 11:57 UTC (permalink / raw)
To: Usama Arif
Cc: Andrew Morton, david, willy, ryan.roberts, linux-mm, r, jack, ajd,
apopple, baohua, baolin.wang, brauner, catalin.marinas, dev.jain,
kees, kevin.brodsky, lance.yang, Liam.Howlett, linux-arm-kernel,
linux-fsdevel, linux-kernel, mhocko, npache, pasha.tatashin,
rmclure, rppt, surenb, vbabka, Al Viro, ziy, hannes, kas,
shakeel.butt, leitao, kernel-team
In-Reply-To: <adjkCOiLgZ_-zovg@lucifer>
On Fri, Apr 10, 2026 at 12:55:42PM +0100, Lorenzo Stoakes wrote:
> On Fri, Apr 10, 2026 at 12:03:03PM +0100, Usama Arif wrote:
> >
> >
> > On 02/04/2026 19:08, Usama Arif wrote:
> > > v2 -> v3: https://lore.kernel.org/all/20260320140315.979307-1-usama.arif@linux.dev/
> > > - Take into account READ_ONLY_THP_FOR_FS for elf alignment by aligning
> > > to HPAGE_PMD_SIZE limited to 2M (Rui)
> > > - Reviewed-by tags for patch 1 from Kiryl and Jan
> > > - Remove preferred_exec_order() (Jan)
> > > - Change ra->order to HPAGE_PMD_ORDER if vma_pages(vma) >= HPAGE_PMD_NR
> > > otherwise use exec_folio_order() with gfp &= ~__GFP_RECLAIM for
> > > do_sync_mmap_readahead().
> > > - Change exec_folio_order() to return 2M (cont-pte size) for 64K base
> > > page size for arm64.
> > > - remove bprm->file NULL check (Matthew)
> > > - Change filp to file (Matthew)
> > > - Improve checking of p_vaddr and p_vaddr (Rui and Matthew)
> > >
> >
> > Hello!
> >
> > Just wanted to check if there was any feedback/review on the latest
> > revision?
>
> It's -rc7, this is definitely something for next cycle :)
>
> On my part, my upstream bandwidth has drastically reduced, and review is
> probably going to have to be a hobbyist thing at least for now.
>
> Also, not to be mean but:
>
> $ git log -E -i --grep "(Reviewed|Acked)-by: Usama Arif" --oneline | wc -l
> 21
>
> So... :)
>
> Review in mm is very lop-sided, let's try to balance it out a bit!
>
> >
> > Thanks!
> >
>
> Thanks, Lorenzo
(Note that we're in a 'quiet period' from here until -rc1 of next cycle and
won't be taking anything new until then. We plan to do this from around rc5 or
rc6 of each cycle in future).
^ permalink raw reply
* Re: [PATCH] arm64: rsi: use linear-map alias for realm config buffer
From: Catalin Marinas @ 2026-04-10 11:57 UTC (permalink / raw)
To: linux-kernel, linux-arm-kernel, Aneesh Kumar K.V (Arm)
Cc: Will Deacon, Suzuki K Poulose, Steven Price, Gavin Shan
In-Reply-To: <20260407152900.396431-1-aneesh.kumar@kernel.org>
On Tue, 07 Apr 2026 20:59:00 +0530, Aneesh Kumar K.V (Arm) wrote:
> rsi_get_realm_config() passes its argument to virt_to_phys(), but
> &config is a kernel image address and not a linear-map alias.
> On arm64 this triggers the below warning:
>
> virt_to_phys used for non-linear address: (____ptrval____) (config+0x0/0x1000)
> WARNING: arch/arm64/mm/physaddr.c:15 at __virt_to_phys+0x50/0x70, CPU#0: swapper/0
> Modules linked in:
> .....
> Hardware name: linux,dummy-virt (DT)
> pstate: 200000c5 (nzCv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> pc : __virt_to_phys+0x50/0x70
> lr : __virt_to_phys+0x4c/0x70
> .....
> ......
> Call trace:
> __virt_to_phys+0x50/0x70 (P)
> arm64_rsi_init+0xa0/0x1b8
> setup_arch+0x13c/0x1a0
> start_kernel+0x68/0x398
> __primary_switched+0x88/0x90
>
> [...]
Applied to arm64 (for-next/misc), thanks!
[1/1] arm64: rsi: use linear-map alias for realm config buffer
https://git.kernel.org/arm64/c/34e563947c76
I did not add a Fixes tag, it's just a debug warning, otherwise it
functions correctly.
--
Catalin
^ permalink raw reply
* Re: [PATCH] arm64: Kconfig: fix duplicate word in CMDLINE help text
From: Catalin Marinas @ 2026-04-10 11:58 UTC (permalink / raw)
To: Will Deacon, Michael Ugrin; +Cc: linux-arm-kernel, linux-kernel
In-Reply-To: <20260409162413.1120-1-mugrinphoto@gmail.com>
On Thu, 09 Apr 2026 09:24:12 -0700, Michael Ugrin wrote:
> Remove duplicate 'the' in the CMDLINE config help text.
>
>
Applied to arm64 (for-next/misc), thanks!
[1/1] arm64: Kconfig: fix duplicate word in CMDLINE help text
https://git.kernel.org/arm64/c/74b63934abf5
^ permalink raw reply
* Re: [PATCH v3 1/3] PCI: Allow ATS to be always on for CXL.cache capable devices
From: Jason Gunthorpe @ 2026-04-10 12:05 UTC (permalink / raw)
To: Tian, Kevin
Cc: Nicolin Chen, will@kernel.org, robin.murphy@arm.com,
bhelgaas@google.com, joro@8bytes.org, praan@google.com,
baolu.lu@linux.intel.com, miko.lenczewski@arm.com,
linux-arm-kernel@lists.infradead.org, iommu@lists.linux.dev,
linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org,
Williams, Dan J, jonathan.cameron@huawei.com, Vikram Sethi,
linux-cxl@vger.kernel.org
In-Reply-To: <BL1PR11MB527184E183703E14F6C861118C592@BL1PR11MB5271.namprd11.prod.outlook.com>
On Fri, Apr 10, 2026 at 03:13:59AM +0000, Tian, Kevin wrote:
> > From: Jason Gunthorpe <jgg@nvidia.com>
> > Sent: Friday, April 10, 2026 6:53 AM
> >
> > On Thu, Apr 09, 2026 at 03:45:26PM -0700, Nicolin Chen wrote:
> >
> > > One question regarding VM case: if a device is ats_always_on, while
> > > VM somehow doesn't set nested_domain->enable_ats. Should the kernel
> > > at least spit a warning, given that it would surely fail the device?
> >
> > No, just let break, the resulting failure has to be contained to the
> > VM or the platform is broken..
> >
> > The HV can't turn on ATS because we it can't know what invalidations
> > to push so not much other choice.
> >
>
> Taking about in theory - host can append a devtlb invalidation cmd
> after iotlb invalidation (if vcmdq is not used)?
It can't map an ASID to a BDF without shadowing all the STE and CD
tables which we don't do for nesting.
Jason
^ permalink raw reply
* Re: [PATCH v3 0/4] mm: improve large folio readahead and alignment for exec memory
From: Usama Arif @ 2026-04-10 12:05 UTC (permalink / raw)
To: Lorenzo Stoakes
Cc: Andrew Morton, david, willy, ryan.roberts, linux-mm, r, jack, ajd,
apopple, baohua, baolin.wang, brauner, catalin.marinas, dev.jain,
kees, kevin.brodsky, lance.yang, Liam.Howlett, linux-arm-kernel,
linux-fsdevel, linux-kernel, mhocko, npache, pasha.tatashin,
rmclure, rppt, surenb, vbabka, Al Viro, ziy, hannes, kas,
shakeel.butt, leitao, kernel-team
In-Reply-To: <adjkCOiLgZ_-zovg@lucifer>
On 10/04/2026 12:55, Lorenzo Stoakes wrote:
> On Fri, Apr 10, 2026 at 12:03:03PM +0100, Usama Arif wrote:
>>
>>
>> On 02/04/2026 19:08, Usama Arif wrote:
>>> v2 -> v3: https://lore.kernel.org/all/20260320140315.979307-1-usama.arif@linux.dev/
>>> - Take into account READ_ONLY_THP_FOR_FS for elf alignment by aligning
>>> to HPAGE_PMD_SIZE limited to 2M (Rui)
>>> - Reviewed-by tags for patch 1 from Kiryl and Jan
>>> - Remove preferred_exec_order() (Jan)
>>> - Change ra->order to HPAGE_PMD_ORDER if vma_pages(vma) >= HPAGE_PMD_NR
>>> otherwise use exec_folio_order() with gfp &= ~__GFP_RECLAIM for
>>> do_sync_mmap_readahead().
>>> - Change exec_folio_order() to return 2M (cont-pte size) for 64K base
>>> page size for arm64.
>>> - remove bprm->file NULL check (Matthew)
>>> - Change filp to file (Matthew)
>>> - Improve checking of p_vaddr and p_vaddr (Rui and Matthew)
>>>
>>
>> Hello!
>>
>> Just wanted to check if there was any feedback/review on the latest
>> revision?
>
> It's -rc7, this is definitely something for next cycle :)
>
Yeah no worries! Just wanted to check what people thought about it!
> On my part, my upstream bandwidth has drastically reduced, and review is
> probably going to have to be a hobbyist thing at least for now.
>
> Also, not to be mean but:
>
> $ git log -E -i --grep "(Reviewed|Acked)-by: Usama Arif" --oneline | wc -l
> 21
>
> So... :)
>
> Review in mm is very lop-sided, let's try to balance it out a bit!
>
Ah yeah actually I have been reviewing a lot over the last few months.
I dont ack patches that have already been acked-by/reviewed-by maintainers.
as I am not sure if it adds anything. I never really cared about Reviewed/Acked
by/patch count but I can start adding tags if it helps in stats.
The reviews I have done over the last week alone:
https://lore.kernel.org/all/20260408122307.1360475-1-usama.arif@linux.dev/
https://lore.kernel.org/all/20260408123700.1596800-1-usama.arif@linux.dev/
https://lore.kernel.org/all/20260409142256.131676-1-usama.arif@linux.dev/
https://lore.kernel.org/all/20260410114809.3592720-1-usama.arif@linux.dev/
https://lore.kernel.org/all/20260410112433.3248586-1-usama.arif@linux.dev/
https://lore.kernel.org/all/20260331103451.1070175-1-usama.arif@linux.dev/T/#t
https://lore.kernel.org/all/20260401152343.3294686-1-usama.arif@linux.dev/
^ permalink raw reply
* Re: [PATCH 0/3] arm-smmu-v3: Add PMCG child support and update PMU MMIO mapping
From: Robin Murphy @ 2026-04-10 12:07 UTC (permalink / raw)
To: Peng Fan
Cc: Will Deacon, Joerg Roedel, Rob Herring, Krzysztof Kozlowski,
Conor Dooley, Mark Rutland, linux-arm-kernel, iommu, devicetree,
linux-kernel, linux-perf-users, Peng Fan
In-Reply-To: <adZcaEKm3vIYSy3N@shlinux89>
On 08/04/2026 2:47 pm, Peng Fan wrote:
> On Wed, Apr 08, 2026 at 12:15:31PM +0100, Robin Murphy wrote:
>> On 2026-04-08 8:51 am, Peng Fan (OSS) wrote:
>>> This patch series adds proper support for describing and probing the
>>> Arm SMMU v3 PMCG (Performance Monitor Control Group) as a child node of
>>> the SMMU in Devicetree, and updates the relevant drivers accordingly.
>>>
>>> The SMMU v3 architecture allows an optional PMCG block, typically
>>> associated with TCUs, to be implemented within the SMMU register
>>> address space. For example, mmu700 PMCG is at the offset 0x2000 of the
>>> TCU page 0.
>>
>> But what's wrong with the existing binding? Especially given that it even has
>> an upstream user already:
>>
>> https://git.kernel.org/torvalds/c/aef9703dcbf8
>>
>>> Patch 1 updates the SMMU v3 Devicetree binding to allow PMCG child nodes,
>>> referencing the existing arm,smmu-v3-pmcg binding.
>>>
>>> Patch 2 updates the arm-smmu-v3 driver to populate platform devices for
>>> child nodes described in DT once the SMMU probe succeeds.
>>>
>>> Patch 3 updates the SMMUv3 PMU driver to correctly handle MMIO mapping when
>>> PMCG is described as a child node. The PMCG registers occupy a sub-region
>>> of the parent SMMU MMIO window, which is already requested by the SMMU
>>
>> That has not been the case since 52f3fab0067d ("iommu/arm-smmu-v3: Don't
>> reserve implementation defined register space") nearly 6 years ago, where the
>> whole purpose was to support Arm's PMCG implementation properly. What kernel
>> is this based on?
>
> Seems I am wrong. I thought PMCG is in page 0, so there were resource
> conflicts. I just retest without this patchset, all goes well.
>
> But from dt perspective, should the TCU PMCG node be child node of
> SMMU node?
No. PMCGs can be used entirely independently of the SMMU itself, and
while most of the events do relate to SMMU translation and thus aren't
necessarily meaningful if it's not in use, there are still some which
can be useful for basic traffic counting, monitoring GPT/translation
activity from _other_ security states (if observation is delegated to
Non-Secure) and possibly other things, even if the "main" Non-Secure
SMMU interface isn't advertised at all. It would be unreasonable to
require the SMMU node to be present and enabled *and* have a driver to
populate PMCGs, to monitor events which are outside the scope of that
driver.
Thanks,
Robin.
^ permalink raw reply
* Re: [PATCH v5 4/4] arm64: errata: Work around early CME DVMSync acknowledgement
From: Will Deacon @ 2026-04-10 12:09 UTC (permalink / raw)
To: Catalin Marinas; +Cc: linux-arm-kernel, James Morse, Mark Rutland, Mark Brown
In-Reply-To: <20260407102848.2266988-5-catalin.marinas@arm.com>
On Tue, Apr 07, 2026 at 11:28:44AM +0100, Catalin Marinas wrote:
> C1-Pro acknowledges DVMSync messages before completing the SME/CME
> memory accesses. Work around this by issuing an IPI to the affected CPUs
> if they are running in EL0 with SME enabled.
>
> Note that we avoid the local DSB in the IPI handler as the kernel runs
> with SCTLR_EL1.IESB=1. This is sufficient to complete SME memory
> accesses at EL0 on taking an exception to EL1. On the return to user
> path, no barrier is necessary either. See the comment in
> sme_set_active() and the more detailed explanation in the link below.
>
> To avoid a potential IPI flood from malicious applications (e.g.
> madvise(MADV_PAGEOUT) in a tight loop), track where a process is active
> via mm_cpumask() and only interrupt those CPUs.
>
> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
> Link: https://lore.kernel.org/r/ablEXwhfKyJW1i7l@J2N7QTR9R3
> Cc: Will Deacon <will@kernel.org>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: James Morse <james.morse@arm.com>
> Cc: Mark Brown <broonie@kernel.org>
> ---
> Documentation/arch/arm64/silicon-errata.rst | 2 +
> arch/arm64/Kconfig | 12 ++++
> arch/arm64/include/asm/cpucaps.h | 2 +
> arch/arm64/include/asm/fpsimd.h | 21 ++++++
> arch/arm64/include/asm/tlbbatch.h | 10 ++-
> arch/arm64/include/asm/tlbflush.h | 72 ++++++++++++++++++-
> arch/arm64/kernel/cpu_errata.c | 30 ++++++++
> arch/arm64/kernel/entry-common.c | 3 +
> arch/arm64/kernel/fpsimd.c | 79 +++++++++++++++++++++
> arch/arm64/kernel/process.c | 36 ++++++++++
> arch/arm64/tools/cpucaps | 1 +
> 11 files changed, 264 insertions(+), 4 deletions(-)
[...]
> diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
> index 489554931231..4c328b7c79ba 100644
> --- a/arch/arm64/kernel/process.c
> +++ b/arch/arm64/kernel/process.c
> @@ -26,6 +26,7 @@
> #include <linux/reboot.h>
> #include <linux/interrupt.h>
> #include <linux/init.h>
> +#include <linux/cpumask.h>
> #include <linux/cpu.h>
> #include <linux/elfcore.h>
> #include <linux/pm.h>
> @@ -339,8 +340,41 @@ void flush_thread(void)
> flush_gcs();
> }
>
> +#ifdef CONFIG_ARM64_ERRATUM_4193714
> +
> +static void arch_dup_tlbbatch_mask(struct task_struct *dst)
> +{
> + /*
> + * Clear the inherited cpumask with memset() to cover both cases where
> + * cpumask_var_t is a pointer or an array. It will be allocated lazily
> + * in sme_dvmsync_add_pending() if CPUMASK_OFFSTACK=y.
> + */
> + if (alternative_has_cap_unlikely(ARM64_WORKAROUND_4193714))
> + memset(&dst->tlb_ubc.arch.cpumask, 0,
> + sizeof(dst->tlb_ubc.arch.cpumask));
nit: use cpumask_clear() instead?
Will
^ permalink raw reply
* Re: [PATCH v5 0/4] arm64: Work around C1-Pro erratum 4193714 (CVE-2026-0995)
From: Will Deacon @ 2026-04-10 12:11 UTC (permalink / raw)
To: Catalin Marinas; +Cc: linux-arm-kernel, James Morse, Mark Rutland, Mark Brown
In-Reply-To: <20260407102848.2266988-1-catalin.marinas@arm.com>
On Tue, Apr 07, 2026 at 11:28:40AM +0100, Catalin Marinas wrote:
> That's version 5 of the C1-Pro workaround. Version 3 here:
>
> https://lore.kernel.org/r/20260402101246.3870036-1-catalin.marinas@arm.com
I left a nit on the final patch but, regardless, this looks good to me
so:
Reviewed-by: Will Deacon <will@kernel.org>
Will
^ permalink raw reply
* Re: [PATCH v3 0/4] mm: improve large folio readahead and alignment for exec memory
From: Lorenzo Stoakes @ 2026-04-10 12:13 UTC (permalink / raw)
To: Usama Arif
Cc: Andrew Morton, david, willy, ryan.roberts, linux-mm, r, jack, ajd,
apopple, baohua, baolin.wang, brauner, catalin.marinas, dev.jain,
kees, kevin.brodsky, lance.yang, Liam.Howlett, linux-arm-kernel,
linux-fsdevel, linux-kernel, mhocko, npache, pasha.tatashin,
rmclure, rppt, surenb, vbabka, Al Viro, ziy, hannes, kas,
shakeel.butt, leitao, kernel-team
In-Reply-To: <262a41db-a425-4362-bb67-df61119625d5@linux.dev>
On Fri, Apr 10, 2026 at 01:05:40PM +0100, Usama Arif wrote:
>
>
> On 10/04/2026 12:55, Lorenzo Stoakes wrote:
> > On Fri, Apr 10, 2026 at 12:03:03PM +0100, Usama Arif wrote:
> >>
> >>
> >> On 02/04/2026 19:08, Usama Arif wrote:
> >>> v2 -> v3: https://lore.kernel.org/all/20260320140315.979307-1-usama.arif@linux.dev/
> >>> - Take into account READ_ONLY_THP_FOR_FS for elf alignment by aligning
> >>> to HPAGE_PMD_SIZE limited to 2M (Rui)
> >>> - Reviewed-by tags for patch 1 from Kiryl and Jan
> >>> - Remove preferred_exec_order() (Jan)
> >>> - Change ra->order to HPAGE_PMD_ORDER if vma_pages(vma) >= HPAGE_PMD_NR
> >>> otherwise use exec_folio_order() with gfp &= ~__GFP_RECLAIM for
> >>> do_sync_mmap_readahead().
> >>> - Change exec_folio_order() to return 2M (cont-pte size) for 64K base
> >>> page size for arm64.
> >>> - remove bprm->file NULL check (Matthew)
> >>> - Change filp to file (Matthew)
> >>> - Improve checking of p_vaddr and p_vaddr (Rui and Matthew)
> >>>
> >>
> >> Hello!
> >>
> >> Just wanted to check if there was any feedback/review on the latest
> >> revision?
> >
> > It's -rc7, this is definitely something for next cycle :)
> >
>
> Yeah no worries! Just wanted to check what people thought about it!
We'll come back to it! With LSF coming too I think people are fairly distracted
as well.
>
> > On my part, my upstream bandwidth has drastically reduced, and review is
> > probably going to have to be a hobbyist thing at least for now.
> >
> > Also, not to be mean but:
> >
> > $ git log -E -i --grep "(Reviewed|Acked)-by: Usama Arif" --oneline | wc -l
> > 21
> >
> > So... :)
> >
> > Review in mm is very lop-sided, let's try to balance it out a bit!
> >
>
> Ah yeah actually I have been reviewing a lot over the last few months.
Good :)
> I dont ack patches that have already been acked-by/reviewed-by maintainers.
You should do that, it is meaningful. If you think a patch is OK, it's how you
say so!
Maintainers get things wrong too by the way, assume we are wrong and try to find
issues, this is how a healthy technical community operates (as long as everybody
is civil about it :)
> as I am not sure if it adds anything. I never really cared about Reviewed/Acked
> by/patch count but I can start adding tags if it helps in stats.
It's the only metric I can quickly bring up, so sorry that in this case I got it
wrong, but the overall point remains the same - we want to see a balance of
review and contributions, right now the two are really very lopsided!
>
> The reviews I have done over the last week alone:
> https://lore.kernel.org/all/20260408122307.1360475-1-usama.arif@linux.dev/
> https://lore.kernel.org/all/20260408123700.1596800-1-usama.arif@linux.dev/
> https://lore.kernel.org/all/20260409142256.131676-1-usama.arif@linux.dev/
> https://lore.kernel.org/all/20260410114809.3592720-1-usama.arif@linux.dev/
> https://lore.kernel.org/all/20260410112433.3248586-1-usama.arif@linux.dev/
> https://lore.kernel.org/all/20260331103451.1070175-1-usama.arif@linux.dev/T/#t
> https://lore.kernel.org/all/20260401152343.3294686-1-usama.arif@linux.dev/
>
>
>
>
>
Cheers, Lorenzo
^ permalink raw reply
* [patch 00/38] treewide: Cleanup LATCH, CLOCK_TICK_RATE and get_cycles() [ab]use
From: Thomas Gleixner @ 2026-04-10 12:18 UTC (permalink / raw)
To: LKML
Cc: Arnd Bergmann, x86, Lu Baolu, iommu, Michael Grzeschik, netdev,
linux-wireless, Herbert Xu, linux-crypto, Vlastimil Babka,
linux-mm, David Woodhouse, Bernie Thompson, linux-fbdev,
Theodore Tso, linux-ext4, Andrew Morton, Uladzislau Rezki,
Marco Elver, Dmitry Vyukov, kasan-dev, Andrey Ryabinin,
Thomas Sailer, linux-hams, Jason A. Donenfeld, Richard Henderson,
linux-alpha, Russell King, linux-arm-kernel, Catalin Marinas,
Huacai Chen, loongarch, Geert Uytterhoeven, linux-m68k,
Dinh Nguyen, Jonas Bonn, linux-openrisc, Helge Deller,
linux-parisc, Michael Ellerman, linuxppc-dev, Paul Walmsley,
linux-riscv, Heiko Carstens, linux-s390, David S. Miller,
sparclinux
First of all sorry for the insanely big Cc list, but people can't make
their mind up whether they want to be Cc'ed on everything or not. So I'm
opting for the worst case to cater to the people who want to be Cc'ed on
everything and assume that the rest of you got used to it by now. I really
wanted this to be more confined but a treewide cleanup does not give a lot
of options.
That said, let me explain what this is about.
1) LATCH
The LATCH define goes back to Linux version 0.1 and has survived until
today for the very wrong reasons.
Initially it was based on the x86 PIT frequency and also steered the
timekeeping conversions.
With the arrival of non x86 architectures it got changed to be based
on CLOCK_TICK_RATE in order not to change core code which depended on
LATCH.
That all got meaningless when timers, timekeeping and scheduling
infrastructure got rewritten more than two decades ago.
But there is still a lonely survivor in arch/x86/kernel/apm_32.c
which dates back to Linux 1.3.46 (Dec. 1995)
Which causes the next historical gem
2) CLOCK_TICK_RATE
When Linux got expanded beyond i386 LATCH was made "flexible" by
basing it on CLOCK_TICK_RATE to adjust for other frequencies than the
i386 PIT frequency.
As LATCH this got meaningless long ago and for amusement value it got
copied into new architectures arriving way after it got obsolete for
no reason but with comments to the effect that it's meaningless
And of course it had a lonely survivor in arch/x86/kernel/setup.c
despite it being only an alias for PIT_TICK_RATE for a very long time.
3) get_cycles()
That was introduced in 2.1.133pre4 (Dec. 1998) to utilize the back
then brand new TSC. The introduction broke everything except i386 SMP
with a CPU having a TSC and got then fixed up within a couple of days
with empty stubs returning 0 and #ifdeffery for CONFIG_TSC before the
2.2.0 release.
It's amusing that the naming deliberately ignored that TSC is the
acronym for Time Stamp Counter and not Cycle Counter and rather went
for the underlying coincidence that the TSC was running at the same
fixed frequency as the CPU core.
That turned out to be interesting when CPUs started to have frequency
scaling as the TSC then turned into a variable frequency random number
generator.
A decade later CPU designers came to senses and made the TSC invariant
usually running at the nominal CPU frequency, which allowed to use it
for reliable timekeeping purposes.
Non x86 architectures implemented get_cycles() based on whatever
continuously running counter they had available in their CPUs. Some of
them actual CPU cycle counters, but many of them running at a fixed
frequency which was completely unrelated to CPU cycles.
Around 2004/5 the timekeeping subsystem was completely rewritten and
made generic along with the scheduling clock and other related
infrastructure. With that rewrite get_cycles() got mostly obsolete,
but despite it being on the todo list of quite some people it never
ceased to exist and it was just a conveniance vehicle to base other
things like the recent addition of random_get_entropy() on top with a
hideous #ifdef/#define macro maze.
The other remaining use cases are mostly debugging and testing
code. Especially the usage in performance test code is hillarious at
best. While the name get_cycles() suggests that it provides access to
CPU cycles the reality is that it provides a unspecified counter for
most systems, where a lot of architectures simply return 0 because
they either do not have such a counter or did not bother to implement
it at all.
So in fact get_cycles() should have been renamed to get_bogo_cycles()
long ago matching the BogoMIPS "impress your friends" printk which
still exists for historical amusement value.
But the real solution is to remove it all together instead of
proliferating the bogosity.
This is what this series does with the following steps:
1) Cleanup some header dependency hell which got unearthed by the
restructuring and went unnoticed so far. It's amazing how the kernel
build system magically "works". This affects not only x86, but the
main fallout was observed and fixed there. ARM64 and MIPS are at
least as bad as they silently rely on the accidental asm/timex.h
include through a variety of generic headers to make their
architecture code compile. See the changelog and patches specific to
those two.
2) Removal of LATCH
3) Removal of CLOCK_TICK_RATE
4) Consolidation of cycles_t which was a typedef in asm/timex.h
5) Cleanup of read_current_timer() which is only used for delay
calibration and has nothing to do with get_cycles()
6) Cleanup of get_cycles() usage in debug and test code
7) Decoupling of random_get_entropy() from get_cycles()
8) Removal of asm/timex.h includes except for architecture internal
usage where necessary.
At the end get_cycles() survives in a couple of architectures as a purely
architecture internal implementation detail.
This survives compile testing on all architectures except hexagon and nios2
because the current cross tools based on gcc15 do not offer a compiler for
them anymore. Boot tested on x86 and some qemu instances covering only a
few architectures.
The series applies on v7.0-rc7 and with very minor conflicts on -next. It
is also available from git:
git://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git getcycles-v1
Thanks,
tglx
---
arch/alpha/include/asm/timex.h | 33 --------
arch/arc/include/asm/timex.h | 15 ---
arch/arm/include/asm/timex.h | 16 ---
arch/arm64/include/asm/timex.h | 18 ----
arch/hexagon/include/asm/timex.h | 23 -----
arch/m68k/include/asm/timex.h | 42 ----------
arch/microblaze/include/asm/timex.h | 13 ---
arch/mips/include/asm/timex.h | 102 -------------------------
arch/sh/include/asm/timex.h | 24 -----
arch/sparc/include/asm/timex.h | 9 --
arch/sparc/include/asm/timex_32.h | 14 ---
arch/um/include/asm/timex.h | 9 --
b/Documentation/fb/udlfb.rst | 4
b/arch/Kconfig | 10 ++
b/arch/alpha/Kconfig | 1
b/arch/alpha/include/asm/random.h | 14 +++
b/arch/arm/Kconfig | 2
b/arch/arm/include/asm/delay.h | 1
b/arch/arm/include/asm/random.h | 14 +++
b/arch/arm/lib/delay.c | 14 +--
b/arch/arm/mach-omap1/Kconfig | 2
b/arch/arm64/Kconfig | 2
b/arch/arm64/include/asm/io.h | 5 -
b/arch/arm64/include/asm/ptp_vmclock.h | 12 ++
b/arch/arm64/include/asm/random.h | 11 ++
b/arch/arm64/include/asm/rqspinlock.h | 1
b/arch/arm64/kernel/time.c | 6 +
b/arch/arm64/kernel/topology.c | 1
b/arch/arm64/kernel/traps.c | 1
b/arch/arm64/kvm/emulate-nested.c | 1
b/arch/arm64/kvm/hyp/include/hyp/switch.h | 1
b/arch/arm64/lib/delay.c | 1
b/arch/hexagon/Kconfig | 1
b/arch/hexagon/kernel/time.c | 8 +
b/arch/loongarch/Kconfig | 1
b/arch/loongarch/include/asm/random.h | 15 +++
b/arch/loongarch/include/asm/timex.h | 2
b/arch/loongarch/kernel/relocate.c | 1
b/arch/loongarch/kernel/syscall.c | 1
b/arch/loongarch/lib/delay.c | 2
b/arch/m68k/Kconfig | 1
b/arch/m68k/amiga/config.c | 1
b/arch/m68k/include/asm/random.h | 14 +++
b/arch/m68k/kernel/time.c | 2
b/arch/mips/Kconfig | 1
b/arch/mips/generic/init.c | 1
b/arch/mips/include/asm/random.h | 7 +
b/arch/mips/kernel/pm-cps.c | 1
b/arch/mips/kernel/proc.c | 1
b/arch/mips/kernel/relocate.c | 2
b/arch/mips/kernel/time.c | 53 ++++++++++++
b/arch/mips/lib/dump_tlb.c | 1
b/arch/mips/mm/cache.c | 1
b/arch/nios2/Kconfig | 1
b/arch/nios2/include/asm/random.h | 14 +++
b/arch/nios2/include/asm/timex.h | 7 -
b/arch/nios2/kernel/time.c | 4
b/arch/openrisc/Kconfig | 2
b/arch/openrisc/include/asm/random.h | 12 ++
b/arch/openrisc/include/asm/timex.h | 10 --
b/arch/openrisc/lib/delay.c | 8 -
b/arch/parisc/Kconfig | 1
b/arch/parisc/include/asm/random.h | 12 ++
b/arch/parisc/include/asm/timex.h | 10 --
b/arch/parisc/kernel/processor.c | 1
b/arch/parisc/kernel/time.c | 1
b/arch/powerpc/Kconfig | 1
b/arch/powerpc/include/asm/random.h | 13 +++
b/arch/powerpc/include/asm/timex.h | 25 ------
b/arch/powerpc/platforms/cell/spufs/switch.c | 5 -
b/arch/riscv/Kconfig | 2
b/arch/riscv/include/asm/random.h | 25 ++++++
b/arch/riscv/include/asm/timex.h | 23 -----
b/arch/riscv/kernel/unaligned_access_speed.c | 1
b/arch/riscv/kvm/vcpu_timer.c | 1
b/arch/riscv/lib/delay.c | 8 +
b/arch/s390/Kconfig | 1
b/arch/s390/include/asm/random.h | 12 ++
b/arch/s390/include/asm/timex.h | 10 --
b/arch/s390/kernel/time.c | 1
b/arch/s390/kernel/vtime.c | 1
b/arch/sparc/Kconfig | 2
b/arch/sparc/include/asm/random.h | 15 +++
b/arch/sparc/include/asm/timex_64.h | 20 ----
b/arch/sparc/kernel/pcic.c | 1
b/arch/sparc/kernel/time_32.c | 1
b/arch/sparc/kernel/time_64.c | 4
b/arch/sparc/vdso/vclock_gettime.c | 1
b/arch/x86/Kconfig | 4
b/arch/x86/include/asm/iommu.h | 3
b/arch/x86/include/asm/msr.h | 5 -
b/arch/x86/include/asm/percpu.h | 5 -
b/arch/x86/include/asm/percpu_types.h | 17 ++++
b/arch/x86/include/asm/ptp_vmclock.h | 12 ++
b/arch/x86/include/asm/pvclock.h | 1
b/arch/x86/include/asm/random.h | 12 --
b/arch/x86/include/asm/smp.h | 2
b/arch/x86/include/asm/tsc.h | 11 --
b/arch/x86/include/asm/vdso/gettimeofday.h | 5 -
b/arch/x86/kernel/apm_32.c | 4
b/arch/x86/kernel/cpu/mce/core.c | 1
b/arch/x86/kernel/nmi.c | 1
b/arch/x86/kernel/setup.c | 2
b/arch/x86/kernel/smpboot.c | 1
b/arch/x86/kernel/tsc.c | 12 +-
b/arch/x86/lib/delay.c | 8 -
b/crypto/jitterentropy-kcapi.c | 1
b/crypto/tcrypt.c | 84 ++++++++++----------
b/drivers/iommu/intel/dmar.c | 4
b/drivers/iommu/intel/iommu.h | 8 +
b/drivers/irqchip/irq-apple-aic.c | 1
b/drivers/misc/sgi-gru/gruhandles.c | 20 +---
b/drivers/misc/sgi-gru/grukservices.c | 3
b/drivers/misc/sgi-gru/grutlbpurge.c | 5 -
b/drivers/net/arcnet/arc-rimi.c | 4
b/drivers/net/arcnet/arcdevice.h | 20 ----
b/drivers/net/arcnet/com20020.c | 6 -
b/drivers/net/arcnet/com90io.c | 6 -
b/drivers/net/arcnet/com90xx.c | 4
b/drivers/net/hamradio/baycom_epp.c | 51 ------------
b/drivers/net/wireless/ath/wil6210/debugfs.c | 2
b/drivers/net/wireless/ath/wil6210/txrx.c | 6 -
b/drivers/net/wireless/ath/wil6210/txrx_edma.c | 4
b/drivers/net/wireless/ath/wil6210/wil6210.h | 3
b/drivers/ptp/Kconfig | 6 -
b/drivers/ptp/ptp_vmclock.c | 6 -
b/drivers/video/fbdev/udlfb.c | 24 ++---
b/fs/ext4/mballoc.c | 4
b/include/asm-generic/Kbuild | 2
b/include/asm-generic/percpu_types.h | 20 ++++
b/include/linux/compiler_types.h | 1
b/include/linux/delay.h | 2
b/include/linux/jiffies.h | 3
b/include/linux/random.h | 18 ++++
b/include/linux/timex.h | 26 ------
b/include/linux/types.h | 6 +
b/init/calibrate.c | 19 ++--
b/kernel/kcsan/core.c | 3
b/kernel/kcsan/debugfs.c | 8 -
b/kernel/time/timer.c | 1
b/lib/interval_tree_test.c | 17 +---
b/lib/rbtree_test.c | 47 +++++------
b/lib/test_vmalloc.c | 10 +-
b/mm/kasan/sw_tags.c | 2
b/mm/slub.c | 37 +++++----
include/asm-generic/timex.h | 23 -----
146 files changed, 622 insertions(+), 796 deletions(-)
^ permalink raw reply
* [patch 01/38] percpu: Sanitize __percpu_qual include hell
From: Thomas Gleixner @ 2026-04-10 12:18 UTC (permalink / raw)
To: LKML
Cc: Arnd Bergmann, x86, Lu Baolu, iommu, Michael Grzeschik, netdev,
linux-wireless, Herbert Xu, linux-crypto, Vlastimil Babka,
linux-mm, David Woodhouse, Bernie Thompson, linux-fbdev,
Theodore Tso, linux-ext4, Andrew Morton, Uladzislau Rezki,
Marco Elver, Dmitry Vyukov, kasan-dev, Andrey Ryabinin,
Thomas Sailer, linux-hams, Jason A. Donenfeld, Richard Henderson,
linux-alpha, Russell King, linux-arm-kernel, Catalin Marinas,
Huacai Chen, loongarch, Geert Uytterhoeven, linux-m68k,
Dinh Nguyen, Jonas Bonn, linux-openrisc, Helge Deller,
linux-parisc, Michael Ellerman, linuxppc-dev, Paul Walmsley,
linux-riscv, Heiko Carstens, linux-s390, David S. Miller,
sparclinux
In-Reply-To: <20260410120044.031381086@kernel.org>
Slapping __percpu_qual into the next available header is sloppy at best.
It's required by __percpu which is defined in compiler_types.h and that is
meant to be included without requiring a boatload of other headers so that
a struct or function declaration can contain a __percpu qualifier w/o
further prerequisites.
This implicit dependency on linux/percpu.h makes that impossible and causes
a major problem when trying to seperate headers.
Create asm/percpu_types.h and move it there. Include that from
compiler_types.h and the whole recursion problem goes away.
Signed-off-by: Thomas Gleixner <tglx@kernel.org
Cc: Arnd Bergmann <arnd@arndb.de>
---
arch/x86/include/asm/percpu.h | 5 -----
arch/x86/include/asm/percpu_types.h | 17 +++++++++++++++++
include/asm-generic/Kbuild | 1 +
include/asm-generic/percpu_types.h | 20 ++++++++++++++++++++
include/linux/compiler_types.h | 1 +
5 files changed, 39 insertions(+), 5 deletions(-)
--- a/arch/x86/include/asm/percpu.h
+++ b/arch/x86/include/asm/percpu.h
@@ -40,12 +40,10 @@
#endif
#define __percpu_prefix
-#define __percpu_seg_override CONCATENATE(__seg_, __percpu_seg)
#else /* !CONFIG_CC_HAS_NAMED_AS: */
#define __percpu_prefix __force_percpu_prefix
-#define __percpu_seg_override
#endif /* CONFIG_CC_HAS_NAMED_AS */
@@ -82,7 +80,6 @@
#define __force_percpu_prefix
#define __percpu_prefix
-#define __percpu_seg_override
#define PER_CPU_VAR(var) (var)__percpu_rel
@@ -92,8 +89,6 @@
# define __my_cpu_type(var) typeof(var)
# define __my_cpu_ptr(ptr) (ptr)
# define __my_cpu_var(var) (var)
-
-# define __percpu_qual __percpu_seg_override
#else
# define __my_cpu_type(var) typeof(var) __percpu_seg_override
# define __my_cpu_ptr(ptr) (__my_cpu_type(*(ptr))*)(__force uintptr_t)(ptr)
--- /dev/null
+++ b/arch/x86/include/asm/percpu_types.h
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_X86_PERCPU_TYPES_H
+#define _ASM_X86_PERCPU_TYPES_H
+
+#if defined(CONFIG_SMP) && defined(CONFIG_CC_HAS_NAMED_AS)
+#define __percpu_seg_override CONCATENATE(__seg_, __percpu_seg)
+#else /* !CONFIG_CC_HAS_NAMED_AS: */
+#define __percpu_seg_override
+#endif
+
+#if defined(CONFIG_USE_X86_SEG_SUPPORT) && defined(USE_TYPEOF_UNQUAL)
+#define __percpu_qual __percpu_seg_override
+#endif
+
+#include <asm-generic/percpu_types.h>
+
+#endif
--- a/include/asm-generic/Kbuild
+++ b/include/asm-generic/Kbuild
@@ -44,6 +44,7 @@ mandatory-y += module.lds.h
mandatory-y += msi.h
mandatory-y += pci.h
mandatory-y += percpu.h
+mandatory-y += percpu_types.h
mandatory-y += pgalloc.h
mandatory-y += preempt.h
mandatory-y += rqspinlock.h
--- /dev/null
+++ b/include/asm-generic/percpu_types.h
@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_GENERIC_PERCPU_TYPES_H_
+#define _ASM_GENERIC_PERCPU_TYPES_H_
+
+#ifndef __ASSEMBLER__
+/*
+ * __percpu_qual is the qualifier for the percpu named address space.
+ *
+ * Most arches use generic named address space for percpu variables but
+ * some arches define percpu variables in different named address space
+ * (on the x86 arch, percpu variable may be declared as being relative
+ * to the %fs or %gs segments using __seg_fs or __seg_gs named address
+ * space qualifier).
+ */
+#ifndef __percpu_qual
+# define __percpu_qual
+#endif
+
+#endif /* __ASSEMBLER__ */
+#endif /* _ASM_GENERIC_PERCPU_TYPES_H_ */
--- a/include/linux/compiler_types.h
+++ b/include/linux/compiler_types.h
@@ -41,6 +41,7 @@
# define BTF_TYPE_TAG(value) /* nothing */
#endif
+#include <asm/percpu_types.h>
#include <linux/compiler-context-analysis.h>
/* sparse defines __CHECKER__; see Documentation/dev-tools/sparse.rst */
^ permalink raw reply
* [patch 02/38] x86: Cleanup include recursion hell
From: Thomas Gleixner @ 2026-04-10 12:18 UTC (permalink / raw)
To: LKML
Cc: Arnd Bergmann, x86, Lu Baolu, iommu, Michael Grzeschik, netdev,
linux-wireless, Herbert Xu, linux-crypto, Vlastimil Babka,
linux-mm, David Woodhouse, Bernie Thompson, linux-fbdev,
Theodore Tso, linux-ext4, Andrew Morton, Uladzislau Rezki,
Marco Elver, Dmitry Vyukov, kasan-dev, Andrey Ryabinin,
Thomas Sailer, linux-hams, Jason A. Donenfeld, Richard Henderson,
linux-alpha, Russell King, linux-arm-kernel, Catalin Marinas,
Huacai Chen, loongarch, Geert Uytterhoeven, linux-m68k,
Dinh Nguyen, Jonas Bonn, linux-openrisc, Helge Deller,
linux-parisc, Michael Ellerman, linuxppc-dev, Paul Walmsley,
linux-riscv, Heiko Carstens, linux-s390, David S. Miller,
sparclinux
In-Reply-To: <20260410120044.031381086@kernel.org>
Including a random architecture specific header which requires global
headers just to avoid including that header at the two usage sites is
really beyond lazy and tasteless. Including global headers just to get the
__percpu macro from linux/compiler_types.h falls into the same category.
Remove the linux/percpu.h and asm/cpumask.h includes from msr.h and smp.h
and fix the resulting fallout by a simple forward struct declaration and by
including the x86 specific asm/cpumask.h header where it is actually
required.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
---
arch/x86/include/asm/msr.h | 5 +++--
arch/x86/include/asm/pvclock.h | 1 +
arch/x86/include/asm/smp.h | 2 --
arch/x86/include/asm/vdso/gettimeofday.h | 5 ++---
arch/x86/kernel/cpu/mce/core.c | 1 +
arch/x86/kernel/nmi.c | 1 +
arch/x86/kernel/smpboot.c | 1 +
7 files changed, 9 insertions(+), 7 deletions(-)
--- a/arch/x86/include/asm/msr.h
+++ b/arch/x86/include/asm/msr.h
@@ -8,12 +8,11 @@
#include <asm/asm.h>
#include <asm/errno.h>
-#include <asm/cpumask.h>
#include <uapi/asm/msr.h>
#include <asm/shared/msr.h>
+#include <linux/compiler_types.h>
#include <linux/types.h>
-#include <linux/percpu.h>
struct msr_info {
u32 msr_no;
@@ -256,6 +255,8 @@ int msr_set_bit(u32 msr, u8 bit);
int msr_clear_bit(u32 msr, u8 bit);
#ifdef CONFIG_SMP
+struct cpumask;
+
int rdmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h);
int wrmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h);
int rdmsrq_on_cpu(unsigned int cpu, u32 msr_no, u64 *q);
--- a/arch/x86/include/asm/pvclock.h
+++ b/arch/x86/include/asm/pvclock.h
@@ -2,6 +2,7 @@
#ifndef _ASM_X86_PVCLOCK_H
#define _ASM_X86_PVCLOCK_H
+#include <asm/barrier.h>
#include <asm/clocksource.h>
#include <asm/pvclock-abi.h>
--- a/arch/x86/include/asm/smp.h
+++ b/arch/x86/include/asm/smp.h
@@ -5,8 +5,6 @@
#include <linux/cpumask.h>
#include <linux/thread_info.h>
-#include <asm/cpumask.h>
-
DECLARE_PER_CPU_CACHE_HOT(int, cpu_number);
DECLARE_PER_CPU_READ_MOSTLY(cpumask_var_t, cpu_sibling_map);
--- a/arch/x86/include/asm/vdso/gettimeofday.h
+++ b/arch/x86/include/asm/vdso/gettimeofday.h
@@ -11,13 +11,12 @@
#define __ASM_VDSO_GETTIMEOFDAY_H
#ifndef __ASSEMBLER__
-
+#include <clocksource/hyperv_timer.h>
#include <uapi/linux/time.h>
+
#include <asm/vgtod.h>
#include <asm/unistd.h>
-#include <asm/msr.h>
#include <asm/pvclock.h>
-#include <clocksource/hyperv_timer.h>
#include <asm/vdso/sys_call.h>
#define VDSO_HAS_TIME 1
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -48,6 +48,7 @@
#include <linux/vmcore_info.h>
#include <asm/fred.h>
+#include <asm/cpumask.h>
#include <asm/cpu_device_id.h>
#include <asm/processor.h>
#include <asm/traps.h>
--- a/arch/x86/kernel/nmi.c
+++ b/arch/x86/kernel/nmi.c
@@ -26,6 +26,7 @@
#include <linux/sched/clock.h>
#include <linux/kvm_types.h>
+#include <asm/cpumask.h>
#include <asm/cpu_entry_area.h>
#include <asm/traps.h>
#include <asm/mach_traps.h>
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -70,6 +70,7 @@
#include <asm/irq.h>
#include <asm/realmode.h>
#include <asm/cpu.h>
+#include <asm/cpumask.h>
#include <asm/numa.h>
#include <asm/tlbflush.h>
#include <asm/mtrr.h>
^ permalink raw reply
* [patch 03/38] x86/apm: Remove last LATCH usage
From: Thomas Gleixner @ 2026-04-10 12:18 UTC (permalink / raw)
To: LKML
Cc: Arnd Bergmann, x86, Lu Baolu, iommu, Michael Grzeschik, netdev,
linux-wireless, Herbert Xu, linux-crypto, Vlastimil Babka,
linux-mm, David Woodhouse, Bernie Thompson, linux-fbdev,
Theodore Tso, linux-ext4, Andrew Morton, Uladzislau Rezki,
Marco Elver, Dmitry Vyukov, kasan-dev, Andrey Ryabinin,
Thomas Sailer, linux-hams, Jason A. Donenfeld, Richard Henderson,
linux-alpha, Russell King, linux-arm-kernel, Catalin Marinas,
Huacai Chen, loongarch, Geert Uytterhoeven, linux-m68k,
Dinh Nguyen, Jonas Bonn, linux-openrisc, Helge Deller,
linux-parisc, Michael Ellerman, linuxppc-dev, Paul Walmsley,
linux-riscv, Heiko Carstens, linux-s390, David S. Miller,
sparclinux
In-Reply-To: <20260410120044.031381086@kernel.org>
LATCH is a historical leftover and has been replaced with PIT_LATCH in all
other places a decade ago. Replace the last holdout and remove the
definition from jiffies.h.
This allows to remove the otherwise unused CLOCK_TICK_RATE define in the
next step.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
---
arch/x86/kernel/apm_32.c | 4 ++--
include/linux/jiffies.h | 3 ---
2 files changed, 2 insertions(+), 5 deletions(-)
--- a/arch/x86/kernel/apm_32.c
+++ b/arch/x86/kernel/apm_32.c
@@ -1196,9 +1196,9 @@ static void reinit_timer(void)
/* set the clock to HZ */
outb_p(0x34, PIT_MODE); /* binary, mode 2, LSB/MSB, ch 0 */
udelay(10);
- outb_p(LATCH & 0xff, PIT_CH0); /* LSB */
+ outb_p(PIT_LATCH & 0xff, PIT_CH0); /* LSB */
udelay(10);
- outb_p(LATCH >> 8, PIT_CH0); /* MSB */
+ outb_p(PIT_LATCH >> 8, PIT_CH0); /* MSB */
udelay(10);
raw_spin_unlock_irqrestore(&i8253_lock, flags);
#endif
--- a/include/linux/jiffies.h
+++ b/include/linux/jiffies.h
@@ -56,9 +56,6 @@
#define SH_DIV(NOM,DEN,LSH) ( (((NOM) / (DEN)) << (LSH)) \
+ ((((NOM) % (DEN)) << (LSH)) + (DEN) / 2) / (DEN))
-/* LATCH is used in the interval timer and ftape setup. */
-#define LATCH ((CLOCK_TICK_RATE + HZ/2) / HZ) /* For divider */
-
extern void register_refined_jiffies(long clock_tick_rate);
/* TICK_USEC is the time between ticks in usec */
^ permalink raw reply
* [patch 04/38] x86: Use PIT_TICK_RATE instead of CLOCK_TICK_RATE
From: Thomas Gleixner @ 2026-04-10 12:18 UTC (permalink / raw)
To: LKML
Cc: Arnd Bergmann, x86, Lu Baolu, iommu, Michael Grzeschik, netdev,
linux-wireless, Herbert Xu, linux-crypto, Vlastimil Babka,
linux-mm, David Woodhouse, Bernie Thompson, linux-fbdev,
Theodore Tso, linux-ext4, Andrew Morton, Uladzislau Rezki,
Marco Elver, Dmitry Vyukov, kasan-dev, Andrey Ryabinin,
Thomas Sailer, linux-hams, Jason A. Donenfeld, Richard Henderson,
linux-alpha, Russell King, linux-arm-kernel, Catalin Marinas,
Huacai Chen, loongarch, Geert Uytterhoeven, linux-m68k,
Dinh Nguyen, Jonas Bonn, linux-openrisc, Helge Deller,
linux-parisc, Michael Ellerman, linuxppc-dev, Paul Walmsley,
linux-riscv, Heiko Carstens, linux-s390, David S. Miller,
sparclinux
In-Reply-To: <20260410120044.031381086@kernel.org>
CLOCK_TICK_RATE is only used in x86 but defined all over the tree for no
reason with comments that it's scheduled for removal for more than a
decade.
Use PIT_TICK_RATE for registering refined jiffies to get rid of the last
dependency.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
---
arch/x86/kernel/setup.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1268,7 +1268,7 @@ void __init setup_arch(char **cmdline_p)
mcheck_init();
- register_refined_jiffies(CLOCK_TICK_RATE);
+ register_refined_jiffies(PIT_TICK_RATE);
#ifdef CONFIG_EFI
if (efi_enabled(EFI_BOOT))
^ permalink raw reply
* [patch 05/38] treewide: Remove CLOCK_TICK_RATE
From: Thomas Gleixner @ 2026-04-10 12:18 UTC (permalink / raw)
To: LKML
Cc: Arnd Bergmann, x86, Lu Baolu, iommu, Michael Grzeschik, netdev,
linux-wireless, Herbert Xu, linux-crypto, Vlastimil Babka,
linux-mm, David Woodhouse, Bernie Thompson, linux-fbdev,
Theodore Tso, linux-ext4, Andrew Morton, Uladzislau Rezki,
Marco Elver, Dmitry Vyukov, kasan-dev, Andrey Ryabinin,
Thomas Sailer, linux-hams, Jason A. Donenfeld, Richard Henderson,
linux-alpha, Russell King, linux-arm-kernel, Catalin Marinas,
Huacai Chen, loongarch, Geert Uytterhoeven, linux-m68k,
Dinh Nguyen, Jonas Bonn, linux-openrisc, Helge Deller,
linux-parisc, Michael Ellerman, linuxppc-dev, Paul Walmsley,
linux-riscv, Heiko Carstens, linux-s390, David S. Miller,
sparclinux
In-Reply-To: <20260410120044.031381086@kernel.org>
This has been scheduled for removal more than a decade ago and the comments
related to it have been dutifully ignored. The last dependencies are gone.
Remove it along with various now empty asm/timex.h files.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
---
arch/alpha/include/asm/timex.h | 4 ----
arch/arc/include/asm/timex.h | 15 ---------------
arch/arm/mach-omap1/Kconfig | 2 +-
arch/hexagon/include/asm/timex.h | 3 ---
arch/m68k/include/asm/timex.h | 15 ---------------
arch/microblaze/include/asm/timex.h | 13 -------------
arch/mips/include/asm/timex.h | 8 --------
arch/openrisc/include/asm/timex.h | 3 ---
arch/parisc/include/asm/timex.h | 2 --
arch/powerpc/include/asm/timex.h | 2 --
arch/s390/include/asm/timex.h | 2 --
arch/sh/include/asm/timex.h | 24 ------------------------
arch/sparc/include/asm/timex.h | 2 +-
arch/sparc/include/asm/timex_32.h | 14 --------------
arch/sparc/include/asm/timex_64.h | 2 --
arch/um/include/asm/timex.h | 9 ---------
arch/x86/include/asm/timex.h | 3 ---
17 files changed, 2 insertions(+), 121 deletions(-)
--- a/arch/alpha/include/asm/timex.h
+++ b/arch/alpha/include/asm/timex.h
@@ -7,10 +7,6 @@
#ifndef _ASMALPHA_TIMEX_H
#define _ASMALPHA_TIMEX_H
-/* With only one or two oddballs, we use the RTC as the ticker, selecting
- the 32.768kHz reference clock, which nicely divides down to our HZ. */
-#define CLOCK_TICK_RATE 32768
-
/*
* Standard way to access the cycle counter.
* Currently only used on SMP for scheduling.
--- a/arch/arc/include/asm/timex.h
+++ /dev/null
@@ -1,15 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-only */
-/*
- * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
- */
-
-#ifndef _ASM_ARC_TIMEX_H
-#define _ASM_ARC_TIMEX_H
-
-#define CLOCK_TICK_RATE 80000000 /* slated to be removed */
-
-#include <asm-generic/timex.h>
-
-/* XXX: get_cycles() to be implemented with RTSC insn */
-
-#endif /* _ASM_ARC_TIMEX_H */
--- a/arch/arm/mach-omap1/Kconfig
+++ b/arch/arm/mach-omap1/Kconfig
@@ -74,7 +74,7 @@ config OMAP_32K_TIMER
currently only available for OMAP16XX, 24XX, 34XX, OMAP4/5 and DRA7XX.
On OMAP2PLUS this value is only used for CONFIG_HZ and
- CLOCK_TICK_RATE compile time calculation.
+ timer frequency compile time calculation.
The actual timer selection is done in the board file
through the (DT_)MACHINE_START structure.
--- a/arch/hexagon/include/asm/timex.h
+++ b/arch/hexagon/include/asm/timex.h
@@ -9,9 +9,6 @@
#include <asm-generic/timex.h>
#include <asm/hexagon_vm.h>
-/* Using TCX0 as our clock. CLOCK_TICK_RATE scheduled to be removed. */
-#define CLOCK_TICK_RATE 19200
-
#define ARCH_HAS_READ_CURRENT_TIMER
static inline int read_current_timer(unsigned long *timer_val)
--- a/arch/m68k/include/asm/timex.h
+++ b/arch/m68k/include/asm/timex.h
@@ -7,21 +7,6 @@
#ifndef _ASMm68K_TIMEX_H
#define _ASMm68K_TIMEX_H
-#ifdef CONFIG_COLDFIRE
-/*
- * CLOCK_TICK_RATE should give the underlying frequency of the tick timer
- * to make ntp work best. For Coldfires, that's the main clock.
- */
-#include <asm/coldfire.h>
-#define CLOCK_TICK_RATE MCF_CLK
-#else
-/*
- * This default CLOCK_TICK_RATE is probably wrong for many 68k boards
- * Users of those boards will need to check and modify accordingly
- */
-#define CLOCK_TICK_RATE 1193180 /* Underlying HZ */
-#endif
-
typedef unsigned long cycles_t;
static inline cycles_t get_cycles(void)
--- a/arch/microblaze/include/asm/timex.h
+++ /dev/null
@@ -1,13 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-/*
- * Copyright (C) 2006 Atmark Techno, Inc.
- */
-
-#ifndef _ASM_MICROBLAZE_TIMEX_H
-#define _ASM_MICROBLAZE_TIMEX_H
-
-#include <asm-generic/timex.h>
-
-#define CLOCK_TICK_RATE 1000 /* Timer input freq. */
-
-#endif /* _ASM_TIMEX_H */
--- a/arch/mips/include/asm/timex.h
+++ b/arch/mips/include/asm/timex.h
@@ -19,14 +19,6 @@
#include <asm/cpu-type.h>
/*
- * This is the clock rate of the i8253 PIT. A MIPS system may not have
- * a PIT by the symbol is used all over the kernel including some APIs.
- * So keeping it defined to the number for the PIT is the only sane thing
- * for now.
- */
-#define CLOCK_TICK_RATE 1193182
-
-/*
* Standard way to access the cycle counter.
* Currently only used on SMP for scheduling.
*
--- a/arch/openrisc/include/asm/timex.h
+++ b/arch/openrisc/include/asm/timex.h
@@ -25,9 +25,6 @@ static inline cycles_t get_cycles(void)
}
#define get_cycles get_cycles
-/* This isn't really used any more */
-#define CLOCK_TICK_RATE 1000
-
#define ARCH_HAS_READ_CURRENT_TIMER
#endif
--- a/arch/parisc/include/asm/timex.h
+++ b/arch/parisc/include/asm/timex.h
@@ -9,8 +9,6 @@
#include <asm/special_insns.h>
-#define CLOCK_TICK_RATE 1193180 /* Underlying HZ */
-
typedef unsigned long cycles_t;
static inline cycles_t get_cycles(void)
--- a/arch/powerpc/include/asm/timex.h
+++ b/arch/powerpc/include/asm/timex.h
@@ -11,8 +11,6 @@
#include <asm/cputable.h>
#include <asm/vdso/timebase.h>
-#define CLOCK_TICK_RATE 1024000 /* Underlying HZ */
-
typedef unsigned long cycles_t;
static inline cycles_t get_cycles(void)
--- a/arch/s390/include/asm/timex.h
+++ b/arch/s390/include/asm/timex.h
@@ -177,8 +177,6 @@ static inline void local_tick_enable(uns
set_clock_comparator(get_lowcore()->clock_comparator);
}
-#define CLOCK_TICK_RATE 1193180 /* Underlying HZ */
-
typedef unsigned long cycles_t;
static __always_inline unsigned long get_tod_clock(void)
--- a/arch/sh/include/asm/timex.h
+++ /dev/null
@@ -1,24 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-/*
- * linux/include/asm-sh/timex.h
- *
- * sh architecture timex specifications
- */
-#ifndef __ASM_SH_TIMEX_H
-#define __ASM_SH_TIMEX_H
-
-/*
- * Only parts using the legacy CPG code for their clock framework
- * implementation need to define their own Pclk value. If provided, this
- * can be used for accurately setting CLOCK_TICK_RATE, otherwise we
- * simply fall back on the i8253 PIT value.
- */
-#ifdef CONFIG_SH_PCLK_FREQ
-#define CLOCK_TICK_RATE (CONFIG_SH_PCLK_FREQ / 4) /* Underlying HZ */
-#else
-#define CLOCK_TICK_RATE 1193180
-#endif
-
-#include <asm-generic/timex.h>
-
-#endif /* __ASM_SH_TIMEX_H */
--- a/arch/sparc/include/asm/timex.h
+++ b/arch/sparc/include/asm/timex.h
@@ -4,6 +4,6 @@
#if defined(__sparc__) && defined(__arch64__)
#include <asm/timex_64.h>
#else
-#include <asm/timex_32.h>
+#include <asm-generic/timex.h>
#endif
#endif
--- a/arch/sparc/include/asm/timex_32.h
+++ /dev/null
@@ -1,14 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-/*
- * linux/include/asm/timex.h
- *
- * sparc architecture timex specifications
- */
-#ifndef _ASMsparc_TIMEX_H
-#define _ASMsparc_TIMEX_H
-
-#define CLOCK_TICK_RATE 1193180 /* Underlying HZ */
-
-#include <asm-generic/timex.h>
-
-#endif
--- a/arch/sparc/include/asm/timex_64.h
+++ b/arch/sparc/include/asm/timex_64.h
@@ -9,8 +9,6 @@
#include <asm/timer.h>
-#define CLOCK_TICK_RATE 1193180 /* Underlying HZ */
-
/* Getting on the cycle counter on sparc64. */
typedef unsigned long cycles_t;
#define get_cycles() tick_ops->get_tick()
--- a/arch/um/include/asm/timex.h
+++ /dev/null
@@ -1,9 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef __UM_TIMEX_H
-#define __UM_TIMEX_H
-
-#define CLOCK_TICK_RATE (HZ)
-
-#include <asm-generic/timex.h>
-
-#endif
--- a/arch/x86/include/asm/timex.h
+++ b/arch/x86/include/asm/timex.h
@@ -14,9 +14,6 @@ static inline unsigned long random_get_e
}
#define random_get_entropy random_get_entropy
-/* Assume we use the PIT time source for the clock tick */
-#define CLOCK_TICK_RATE PIT_TICK_RATE
-
#define ARCH_HAS_READ_CURRENT_TIMER
#endif /* _ASM_X86_TIMEX_H */
^ permalink raw reply
* [patch 06/38] calibrate: Rework delay timer calibration
From: Thomas Gleixner @ 2026-04-10 12:18 UTC (permalink / raw)
To: LKML
Cc: Arnd Bergmann, x86, Lu Baolu, iommu, Michael Grzeschik, netdev,
linux-wireless, Herbert Xu, linux-crypto, Vlastimil Babka,
linux-mm, David Woodhouse, Bernie Thompson, linux-fbdev,
Theodore Tso, linux-ext4, Andrew Morton, Uladzislau Rezki,
Marco Elver, Dmitry Vyukov, kasan-dev, Andrey Ryabinin,
Thomas Sailer, linux-hams, Jason A. Donenfeld, Richard Henderson,
linux-alpha, Russell King, linux-arm-kernel, Catalin Marinas,
Huacai Chen, loongarch, Geert Uytterhoeven, linux-m68k,
Dinh Nguyen, Jonas Bonn, linux-openrisc, Helge Deller,
linux-parisc, Michael Ellerman, linuxppc-dev, Paul Walmsley,
linux-riscv, Heiko Carstens, linux-s390, David S. Miller,
sparclinux
In-Reply-To: <20260410120044.031381086@kernel.org>
The header define in asm/timex,h and the naming of the function to read the
delay timer are confusing at best.
Convert it to a config switch selected by the archictures, which provide
the functionality, and rename the function to delay_read_timer(), which
makes the purpose clear. Move the declaration to linux/delay.h where it
belongs.
Remove the resulting empty asm/timex.h files as well.
No functional change.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
---
arch/Kconfig | 3 +++
arch/arm/Kconfig | 1 +
arch/arm/include/asm/delay.h | 1 -
arch/arm/include/asm/timex.h | 5 ++++-
arch/arm/lib/delay.c | 10 ++++------
arch/hexagon/Kconfig | 1 +
arch/hexagon/include/asm/timex.h | 20 --------------------
arch/hexagon/kernel/time.c | 8 +++++++-
arch/openrisc/Kconfig | 1 +
arch/openrisc/include/asm/timex.h | 2 --
arch/openrisc/lib/delay.c | 9 ++++-----
arch/riscv/Kconfig | 1 +
arch/riscv/include/asm/timex.h | 8 --------
arch/riscv/lib/delay.c | 7 ++++++-
arch/sparc/Kconfig | 1 +
arch/sparc/include/asm/timex_64.h | 2 --
arch/sparc/kernel/time_64.c | 4 ++--
arch/x86/Kconfig | 1 +
arch/x86/include/asm/timex.h | 2 --
arch/x86/lib/delay.c | 8 +++-----
include/asm-generic/timex.h | 7 -------
include/linux/delay.h | 2 ++
include/linux/timex.h | 2 --
init/calibrate.c | 19 +++++++++----------
24 files changed, 50 insertions(+), 75 deletions(-)
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -363,6 +363,9 @@ config ARCH_HAS_DMA_CLEAR_UNCACHED
config ARCH_HAS_CPU_FINALIZE_INIT
bool
+config ARCH_HAS_DELAY_TIMER
+ bool
+
# The architecture has a per-task state that includes the mm's PASID
config ARCH_HAS_CPU_PASID
bool
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -11,6 +11,7 @@ config ARM
select ARCH_HAS_CPU_FINALIZE_INIT if MMU
select ARCH_HAS_CURRENT_STACK_POINTER
select ARCH_HAS_DEBUG_VIRTUAL if MMU
+ select ARCH_HAS_DELAY_TIMER
select ARCH_HAS_DMA_ALLOC if MMU
select ARCH_HAS_DMA_OPS
select ARCH_HAS_DMA_WRITE_COMBINE if !ARM_DMA_MEM_BUFFERABLE
--- a/arch/arm/include/asm/delay.h
+++ b/arch/arm/include/asm/delay.h
@@ -91,7 +91,6 @@ extern void __loop_udelay(unsigned long
extern void __loop_const_udelay(unsigned long);
/* Delay-loop timer registration. */
-#define ARCH_HAS_READ_CURRENT_TIMER
extern void register_current_timer_delay(const struct delay_timer *timer);
#endif /* __ASSEMBLY__ */
--- a/arch/arm/include/asm/timex.h
+++ b/arch/arm/include/asm/timex.h
@@ -10,7 +10,10 @@
#define _ASMARM_TIMEX_H
typedef unsigned long cycles_t;
-#define get_cycles() ({ cycles_t c; read_current_timer(&c) ? 0 : c; })
+// Temporary workaround
+bool delay_read_timer(unsigned long *t);
+
+#define get_cycles() ({ cycles_t c; delay_read_timer(&c) ? 0 : c; })
#define random_get_entropy() (((unsigned long)get_cycles()) ?: random_get_entropy_fallback())
#endif
--- a/arch/arm/lib/delay.c
+++ b/arch/arm/lib/delay.c
@@ -12,7 +12,6 @@
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
-#include <linux/timex.h>
/*
* Default to the loop-based delay implementation.
@@ -27,15 +26,14 @@ static const struct delay_timer *delay_t
static bool delay_calibrated;
static u64 delay_res;
-int read_current_timer(unsigned long *timer_val)
+bool delay_read_timer(unsigned long *timer_val)
{
if (!delay_timer)
- return -ENXIO;
-
+ return false;
*timer_val = delay_timer->read_current_timer();
- return 0;
+ return true;
}
-EXPORT_SYMBOL_GPL(read_current_timer);
+EXPORT_SYMBOL_GPL(delay_read_timer);
static inline u64 cyc_to_ns(u64 cyc, u32 mult, u32 shift)
{
--- a/arch/hexagon/Kconfig
+++ b/arch/hexagon/Kconfig
@@ -5,6 +5,7 @@ comment "Linux Kernel Configuration for
config HEXAGON
def_bool y
select ARCH_32BIT_OFF_T
+ select ARCH_HAS_DELAY_TIMER
select ARCH_HAS_SYNC_DMA_FOR_DEVICE
select ARCH_NO_PREEMPT
select ARCH_WANT_FRAME_POINTERS
--- a/arch/hexagon/include/asm/timex.h
+++ /dev/null
@@ -1,20 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-only */
-/*
- * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
- */
-
-#ifndef _ASM_TIMEX_H
-#define _ASM_TIMEX_H
-
-#include <asm-generic/timex.h>
-#include <asm/hexagon_vm.h>
-
-#define ARCH_HAS_READ_CURRENT_TIMER
-
-static inline int read_current_timer(unsigned long *timer_val)
-{
- *timer_val = __vmgettime();
- return 0;
-}
-
-#endif
--- a/arch/hexagon/kernel/time.c
+++ b/arch/hexagon/kernel/time.c
@@ -6,6 +6,7 @@
*/
#include <linux/init.h>
+#include <linux/delay.h>
#include <linux/clockchips.h>
#include <linux/clocksource.h>
#include <linux/interrupt.h>
@@ -17,7 +18,6 @@
#include <linux/of_irq.h>
#include <linux/module.h>
-#include <asm/delay.h>
#include <asm/hexagon_vm.h>
#include <asm/time.h>
@@ -231,3 +231,9 @@ void __udelay(unsigned long usecs)
cpu_relax(); /* not sure how this improves readability */
}
EXPORT_SYMBOL(__udelay);
+
+bool delay_read_timer(unsigned long *timer_val)
+{
+ *timer_val = __vmgettime();
+ return true;
+}
--- a/arch/openrisc/Kconfig
+++ b/arch/openrisc/Kconfig
@@ -7,6 +7,7 @@
config OPENRISC
def_bool y
select ARCH_32BIT_OFF_T
+ select ARCH_HAS_DELAY_TIMER
select ARCH_HAS_DMA_SET_UNCACHED
select ARCH_HAS_DMA_CLEAR_UNCACHED
select ARCH_HAS_SYNC_DMA_FOR_DEVICE
--- a/arch/openrisc/include/asm/timex.h
+++ b/arch/openrisc/include/asm/timex.h
@@ -25,6 +25,4 @@ static inline cycles_t get_cycles(void)
}
#define get_cycles get_cycles
-#define ARCH_HAS_READ_CURRENT_TIMER
-
#endif
--- a/arch/openrisc/lib/delay.c
+++ b/arch/openrisc/lib/delay.c
@@ -13,18 +13,17 @@
*/
#include <linux/kernel.h>
+#include <linux/delay.h>
#include <linux/export.h>
#include <linux/init.h>
-#include <linux/timex.h>
+
#include <asm/param.h>
-#include <asm/delay.h>
-#include <asm/timex.h>
#include <asm/processor.h>
-int read_current_timer(unsigned long *timer_value)
+bool delay_read_timer(unsigned long *timer_value)
{
*timer_value = get_cycles();
- return 0;
+ return true;
}
void __delay(unsigned long cycles)
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -29,6 +29,7 @@ config RISCV
select ARCH_HAS_DEBUG_VIRTUAL if MMU
select ARCH_HAS_DEBUG_VM_PGTABLE
select ARCH_HAS_DEBUG_WX
+ select ARCH_HAS_DELAY_TIMER
select ARCH_HAS_ELF_CORE_EFLAGS if BINFMT_ELF && ELF_CORE
select ARCH_HAS_FAST_MULTIPLIER
select ARCH_HAS_FORTIFY_SOURCE
--- a/arch/riscv/include/asm/timex.h
+++ b/arch/riscv/include/asm/timex.h
@@ -80,12 +80,4 @@ static inline u64 get_cycles64(void)
return ((u64)hi << 32) | lo;
}
#endif /* CONFIG_64BIT */
-
-#define ARCH_HAS_READ_CURRENT_TIMER
-static inline int read_current_timer(unsigned long *timer_val)
-{
- *timer_val = get_cycles();
- return 0;
-}
-
#endif /* _ASM_RISCV_TIMEX_H */
--- a/arch/riscv/lib/delay.c
+++ b/arch/riscv/lib/delay.c
@@ -6,7 +6,6 @@
#include <linux/delay.h>
#include <linux/math.h>
#include <linux/param.h>
-#include <linux/timex.h>
#include <linux/types.h>
#include <linux/export.h>
@@ -109,3 +108,9 @@ void ndelay(unsigned long nsecs)
__delay(ncycles >> NDELAY_SHIFT);
}
EXPORT_SYMBOL(ndelay);
+
+bool delay_read_timer(unsigned long *timer_val)
+{
+ *timer_val = get_cycles();
+ return true;
+}
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -70,6 +70,7 @@ config SPARC32
config SPARC64
def_bool 64BIT
select ALTERNATE_USER_ADDRESS_SPACE
+ select ARCH_HAS_DELAY_TIMER
select HAVE_FUNCTION_TRACER
select HAVE_FUNCTION_GRAPH_TRACER
select HAVE_KRETPROBES
--- a/arch/sparc/include/asm/timex_64.h
+++ b/arch/sparc/include/asm/timex_64.h
@@ -13,6 +13,4 @@
typedef unsigned long cycles_t;
#define get_cycles() tick_ops->get_tick()
-#define ARCH_HAS_READ_CURRENT_TIMER
-
#endif
--- a/arch/sparc/kernel/time_64.c
+++ b/arch/sparc/kernel/time_64.c
@@ -894,8 +894,8 @@ unsigned long long sched_clock(void)
return ((get_tick() * quotient) >> SPARC64_NSEC_PER_CYC_SHIFT) - offset;
}
-int read_current_timer(unsigned long *timer_val)
+bool delay_read_timer(unsigned long *timer_val)
{
*timer_val = get_tick();
- return 0;
+ return true;
}
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -81,6 +81,7 @@ config X86
select ARCH_HAS_CURRENT_STACK_POINTER
select ARCH_HAS_DEBUG_VIRTUAL
select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
+ select ARCH_HAS_DELAY_TIMER
select ARCH_HAS_DEVMEM_IS_ALLOWED
select ARCH_HAS_DMA_OPS if GART_IOMMU || XEN
select ARCH_HAS_EARLY_DEBUG if KGDB
--- a/arch/x86/include/asm/timex.h
+++ b/arch/x86/include/asm/timex.h
@@ -14,6 +14,4 @@ static inline unsigned long random_get_e
}
#define random_get_entropy random_get_entropy
-#define ARCH_HAS_READ_CURRENT_TIMER
-
#endif /* _ASM_X86_TIMEX_H */
--- a/arch/x86/lib/delay.c
+++ b/arch/x86/lib/delay.c
@@ -14,12 +14,10 @@
#include <linux/export.h>
#include <linux/sched.h>
-#include <linux/timex.h>
#include <linux/preempt.h>
#include <linux/delay.h>
#include <asm/processor.h>
-#include <asm/delay.h>
#include <asm/timer.h>
#include <asm/mwait.h>
@@ -189,13 +187,13 @@ void use_mwaitx_delay(void)
delay_fn = delay_halt;
}
-int read_current_timer(unsigned long *timer_val)
+bool delay_read_timer(unsigned long *timer_val)
{
if (delay_fn == delay_tsc) {
*timer_val = rdtsc();
- return 0;
+ return true;
}
- return -1;
+ return false;
}
void __delay(unsigned long loops)
--- a/include/asm-generic/timex.h
+++ b/include/asm-generic/timex.h
@@ -13,11 +13,4 @@ static inline cycles_t get_cycles(void)
}
#endif
-/*
- * Architectures are encouraged to implement read_current_timer
- * and define this in order to avoid the expensive delay loop
- * calibration during boot.
- */
-#undef ARCH_HAS_READ_CURRENT_TIMER
-
#endif /* __ASM_GENERIC_TIMEX_H */
--- a/include/linux/delay.h
+++ b/include/linux/delay.h
@@ -17,6 +17,8 @@ extern unsigned long loops_per_jiffy;
#include <asm/delay.h>
+bool delay_read_timer(unsigned long *t);
+
/*
* Using udelay() for intervals greater than a few milliseconds can
* risk overflow for high loops_per_jiffy (high bogomips) machines. The
--- a/include/linux/timex.h
+++ b/include/linux/timex.h
@@ -156,8 +156,6 @@ extern int do_clock_adjtime(const clocki
extern void hardpps(const struct timespec64 *, const struct timespec64 *);
-int read_current_timer(unsigned long *timer_val);
-
/* The clock frequency of the i8253/i8254 PIT */
#define PIT_TICK_RATE 1193182ul
--- a/init/calibrate.c
+++ b/init/calibrate.c
@@ -13,7 +13,6 @@
#include <linux/printk.h>
#include <linux/smp.h>
#include <linux/stddef.h>
-#include <linux/timex.h>
unsigned long lpj_fine;
unsigned long preset_lpj;
@@ -25,9 +24,9 @@ static int __init lpj_setup(char *str)
__setup("lpj=", lpj_setup);
-#ifdef ARCH_HAS_READ_CURRENT_TIMER
+#ifdef CONFIG_ARCH_HAS_DELAY_TIMER
-/* This routine uses the read_current_timer() routine and gets the
+/* This routine uses the delay_read_timer() routine and gets the
* loops per jiffy directly, instead of guessing it using delay().
* Also, this code tries to handle non-maskable asynchronous events
* (like SMIs)
@@ -48,13 +47,13 @@ static unsigned long calibrate_delay_dir
int min = -1;
int i;
- if (read_current_timer(&pre_start) < 0 )
+ if (!delay_read_timer(&pre_start))
return 0;
/*
* A simple loop like
* while ( jiffies < start_jiffies+1)
- * start = read_current_timer();
+ * start = delay_read_timer();
* will not do. As we don't really know whether jiffy switch
* happened first or timer_value was read first. And some asynchronous
* event can happen between these two events introducing errors in lpj.
@@ -72,22 +71,22 @@ static unsigned long calibrate_delay_dir
for (i = 0; i < MAX_DIRECT_CALIBRATION_RETRIES; i++) {
pre_start = 0;
- read_current_timer(&start);
+ delay_read_timer(&start);
start_jiffies = jiffies;
while (time_before_eq(jiffies, start_jiffies + 1)) {
pre_start = start;
- read_current_timer(&start);
+ delay_read_timer(&start);
}
- read_current_timer(&post_start);
+ delay_read_timer(&post_start);
pre_end = 0;
end = post_start;
while (time_before_eq(jiffies, start_jiffies + 1 +
DELAY_CALIBRATION_TICKS)) {
pre_end = end;
- read_current_timer(&end);
+ delay_read_timer(&end);
}
- read_current_timer(&post_end);
+ delay_read_timer(&post_end);
timer_rate_max = (post_end - pre_start) /
DELAY_CALIBRATION_TICKS;
^ permalink raw reply
* [patch 08/38] x86/tsc: Use rdtsc() instead of get_cycles()
From: Thomas Gleixner @ 2026-04-10 12:19 UTC (permalink / raw)
To: LKML
Cc: Arnd Bergmann, x86, Lu Baolu, iommu, Michael Grzeschik, netdev,
linux-wireless, Herbert Xu, linux-crypto, Vlastimil Babka,
linux-mm, David Woodhouse, Bernie Thompson, linux-fbdev,
Theodore Tso, linux-ext4, Andrew Morton, Uladzislau Rezki,
Marco Elver, Dmitry Vyukov, kasan-dev, Andrey Ryabinin,
Thomas Sailer, linux-hams, Jason A. Donenfeld, Richard Henderson,
linux-alpha, Russell King, linux-arm-kernel, Catalin Marinas,
Huacai Chen, loongarch, Geert Uytterhoeven, linux-m68k,
Dinh Nguyen, Jonas Bonn, linux-openrisc, Helge Deller,
linux-parisc, Michael Ellerman, linuxppc-dev, Paul Walmsley,
linux-riscv, Heiko Carstens, linux-s390, David S. Miller,
sparclinux
In-Reply-To: <20260410120044.031381086@kernel.org>
This code knows that TSC is available so there is no point to use the TSC
feature guarded get_cycles().
No functional change.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
---
arch/x86/kernel/tsc.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -371,12 +371,12 @@ static u64 tsc_read_refs(u64 *p, int hpe
int i;
for (i = 0; i < MAX_RETRIES; i++) {
- t1 = get_cycles();
+ t1 = rdtsc();
if (hpet)
*p = hpet_readl(HPET_COUNTER) & 0xFFFFFFFF;
else
*p = acpi_pm_read_early();
- t2 = get_cycles();
+ t2 = rdtsc();
if ((t2 - t1) < thresh)
return t2;
}
@@ -468,13 +468,13 @@ static unsigned long pit_calibrate_tsc(u
outb(latch & 0xff, 0x42);
outb(latch >> 8, 0x42);
- tsc = t1 = t2 = get_cycles();
+ tsc = t1 = t2 = rdtsc();
pitcnt = 0;
tscmax = 0;
tscmin = ULONG_MAX;
while ((inb(0x61) & 0x20) == 0) {
- t2 = get_cycles();
+ t2 = rdtsc();
delta = t2 - tsc;
tsc = t2;
if ((unsigned long) delta < tscmin)
@@ -553,9 +553,9 @@ static inline int pit_expect_msb(unsigne
if (!pit_verify_msb(val))
break;
prev_tsc = tsc;
- tsc = get_cycles();
+ tsc = rdtsc();
}
- *deltap = get_cycles() - prev_tsc;
+ *deltap = rdtsc() - prev_tsc;
*tscp = tsc;
/*
^ permalink raw reply
* [patch 07/38] treewide: Consolidate cycles_t
From: Thomas Gleixner @ 2026-04-10 12:19 UTC (permalink / raw)
To: LKML
Cc: Arnd Bergmann, x86, Lu Baolu, iommu, Michael Grzeschik, netdev,
linux-wireless, Herbert Xu, linux-crypto, Vlastimil Babka,
linux-mm, David Woodhouse, Bernie Thompson, linux-fbdev,
Theodore Tso, linux-ext4, Andrew Morton, Uladzislau Rezki,
Marco Elver, Dmitry Vyukov, kasan-dev, Andrey Ryabinin,
Thomas Sailer, linux-hams, Jason A. Donenfeld, Richard Henderson,
linux-alpha, Russell King, linux-arm-kernel, Catalin Marinas,
Huacai Chen, loongarch, Geert Uytterhoeven, linux-m68k,
Dinh Nguyen, Jonas Bonn, linux-openrisc, Helge Deller,
linux-parisc, Michael Ellerman, linuxppc-dev, Paul Walmsley,
linux-riscv, Heiko Carstens, linux-s390, David S. Miller,
sparclinux
In-Reply-To: <20260410120044.031381086@kernel.org>
Most architectures define cycles_t as unsigned long execpt:
- x86 requires it to be 64-bit independent of the 32-bit/64-bit build.
- parisc and mips define it as unsigned int
parisc has no real reason to do so as there are only a few usage sites
which either expand it to a 64-bit value or utilize only the lower
32bits.
mips has no real requirement either.
Move the typedef to types.h and provide a config switch to enforce the
64-bit type for x86.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
---
arch/Kconfig | 4 ++++
arch/alpha/include/asm/timex.h | 3 ---
arch/arm/include/asm/timex.h | 1 -
arch/loongarch/include/asm/timex.h | 2 --
arch/m68k/include/asm/timex.h | 2 --
arch/mips/include/asm/timex.h | 2 --
arch/nios2/include/asm/timex.h | 2 --
arch/parisc/include/asm/timex.h | 2 --
arch/powerpc/include/asm/timex.h | 4 +---
arch/riscv/include/asm/timex.h | 2 --
arch/s390/include/asm/timex.h | 2 --
arch/sparc/include/asm/timex_64.h | 1 -
arch/x86/Kconfig | 1 +
arch/x86/include/asm/tsc.h | 2 --
include/asm-generic/timex.h | 1 -
include/linux/types.h | 6 ++++++
16 files changed, 12 insertions(+), 25 deletions(-)
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -360,6 +360,10 @@ config ARCH_HAS_DMA_SET_UNCACHED
config ARCH_HAS_DMA_CLEAR_UNCACHED
bool
+# cycles_t is always 64bit wide
+config ARCH_HAS_CYCLES_T_64
+ bool
+
config ARCH_HAS_CPU_FINALIZE_INIT
bool
--- a/arch/alpha/include/asm/timex.h
+++ b/arch/alpha/include/asm/timex.h
@@ -15,9 +15,6 @@
* But this only means we'll force a reschedule every 8 seconds or so,
* which isn't an evil thing.
*/
-
-typedef unsigned int cycles_t;
-
static inline cycles_t get_cycles (void)
{
cycles_t ret;
--- a/arch/arm/include/asm/timex.h
+++ b/arch/arm/include/asm/timex.h
@@ -9,7 +9,6 @@
#ifndef _ASMARM_TIMEX_H
#define _ASMARM_TIMEX_H
-typedef unsigned long cycles_t;
// Temporary workaround
bool delay_read_timer(unsigned long *t);
--- a/arch/loongarch/include/asm/timex.h
+++ b/arch/loongarch/include/asm/timex.h
@@ -12,8 +12,6 @@
#include <asm/cpu.h>
#include <asm/cpu-features.h>
-typedef unsigned long cycles_t;
-
#define get_cycles get_cycles
static inline cycles_t get_cycles(void)
--- a/arch/m68k/include/asm/timex.h
+++ b/arch/m68k/include/asm/timex.h
@@ -7,8 +7,6 @@
#ifndef _ASMm68K_TIMEX_H
#define _ASMm68K_TIMEX_H
-typedef unsigned long cycles_t;
-
static inline cycles_t get_cycles(void)
{
return 0;
--- a/arch/mips/include/asm/timex.h
+++ b/arch/mips/include/asm/timex.h
@@ -29,8 +29,6 @@
* We know that all SMP capable CPUs have cycle counters.
*/
-typedef unsigned int cycles_t;
-
/*
* On R4000/R4400 an erratum exists such that if the cycle counter is
* read in the exact moment that it is matching the compare register,
--- a/arch/nios2/include/asm/timex.h
+++ b/arch/nios2/include/asm/timex.h
@@ -5,8 +5,6 @@
#ifndef _ASM_NIOS2_TIMEX_H
#define _ASM_NIOS2_TIMEX_H
-typedef unsigned long cycles_t;
-
extern cycles_t get_cycles(void);
#define get_cycles get_cycles
--- a/arch/parisc/include/asm/timex.h
+++ b/arch/parisc/include/asm/timex.h
@@ -9,8 +9,6 @@
#include <asm/special_insns.h>
-typedef unsigned long cycles_t;
-
static inline cycles_t get_cycles(void)
{
return mfctl(16);
--- a/arch/powerpc/include/asm/timex.h
+++ b/arch/powerpc/include/asm/timex.h
@@ -11,9 +11,7 @@
#include <asm/cputable.h>
#include <asm/vdso/timebase.h>
-typedef unsigned long cycles_t;
-
-static inline cycles_t get_cycles(void)
+ostatic inline cycles_t get_cycles(void)
{
return mftb();
}
--- a/arch/riscv/include/asm/timex.h
+++ b/arch/riscv/include/asm/timex.h
@@ -8,8 +8,6 @@
#include <asm/csr.h>
-typedef unsigned long cycles_t;
-
#ifdef CONFIG_RISCV_M_MODE
#include <asm/clint.h>
--- a/arch/s390/include/asm/timex.h
+++ b/arch/s390/include/asm/timex.h
@@ -177,8 +177,6 @@ static inline void local_tick_enable(uns
set_clock_comparator(get_lowcore()->clock_comparator);
}
-typedef unsigned long cycles_t;
-
static __always_inline unsigned long get_tod_clock(void)
{
union tod_clock clk;
--- a/arch/sparc/include/asm/timex_64.h
+++ b/arch/sparc/include/asm/timex_64.h
@@ -10,7 +10,6 @@
#include <asm/timer.h>
/* Getting on the cycle counter on sparc64. */
-typedef unsigned long cycles_t;
#define get_cycles() tick_ops->get_tick()
#endif
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -79,6 +79,7 @@ config X86
select ARCH_HAS_CPU_FINALIZE_INIT
select ARCH_HAS_CPU_PASID if IOMMU_SVA
select ARCH_HAS_CURRENT_STACK_POINTER
+ select ARCH_HAS_CYCLES_T_64
select ARCH_HAS_DEBUG_VIRTUAL
select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
select ARCH_HAS_DELAY_TIMER
--- a/arch/x86/include/asm/tsc.h
+++ b/arch/x86/include/asm/tsc.h
@@ -67,8 +67,6 @@ static __always_inline u64 rdtsc_ordered
/*
* Standard way to access the cycle counter.
*/
-typedef unsigned long long cycles_t;
-
extern unsigned int cpu_khz;
extern unsigned int tsc_khz;
--- a/include/asm-generic/timex.h
+++ b/include/asm-generic/timex.h
@@ -5,7 +5,6 @@
/*
* If you have a cycle counter, return the value here.
*/
-typedef unsigned long cycles_t;
#ifndef get_cycles
static inline cycles_t get_cycles(void)
{
--- a/include/linux/types.h
+++ b/include/linux/types.h
@@ -270,5 +270,11 @@ struct rcuwait {
struct task_struct __rcu *task;
};
+#ifdef CONFIG_ARCH_HAS_CYCLES_T_64
+typedef unsigned long long cycles_t;
+#else
+typedef unsigned long cycles_t;
+#endif
+
#endif /* __ASSEMBLY__ */
#endif /* _LINUX_TYPES_H */
^ permalink raw reply
* [patch 09/38] iommu/vt-d: Use sched_clock() instead of get_cycles()
From: Thomas Gleixner @ 2026-04-10 12:19 UTC (permalink / raw)
To: LKML
Cc: x86, Lu Baolu, iommu, Arnd Bergmann, Michael Grzeschik, netdev,
linux-wireless, Herbert Xu, linux-crypto, Vlastimil Babka,
linux-mm, David Woodhouse, Bernie Thompson, linux-fbdev,
Theodore Tso, linux-ext4, Andrew Morton, Uladzislau Rezki,
Marco Elver, Dmitry Vyukov, kasan-dev, Andrey Ryabinin,
Thomas Sailer, linux-hams, Jason A. Donenfeld, Richard Henderson,
linux-alpha, Russell King, linux-arm-kernel, Catalin Marinas,
Huacai Chen, loongarch, Geert Uytterhoeven, linux-m68k,
Dinh Nguyen, Jonas Bonn, linux-openrisc, Helge Deller,
linux-parisc, Michael Ellerman, linuxppc-dev, Paul Walmsley,
linux-riscv, Heiko Carstens, linux-s390, David S. Miller,
sparclinux
In-Reply-To: <20260410120044.031381086@kernel.org>
Calculating the timeout from get_cycles() is a historical leftover without
any functional requirement.
Use ktime_get() instead.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Cc: x86@kernel.org
Cc: Lu Baolu <baolu.lu@linux.intel.com>
Cc: iommu@lists.linux.dev
---
arch/x86/include/asm/iommu.h | 3 ---
drivers/iommu/intel/dmar.c | 4 ++--
drivers/iommu/intel/iommu.h | 8 ++++++--
3 files changed, 8 insertions(+), 7 deletions(-)
--- a/arch/x86/include/asm/iommu.h
+++ b/arch/x86/include/asm/iommu.h
@@ -18,9 +18,6 @@ extern bool x86_swiotlb_enable;
#define x86_swiotlb_enable false
#endif
-/* 10 seconds */
-#define DMAR_OPERATION_TIMEOUT ((cycles_t) tsc_khz*10*1000)
-
static inline int __init
arch_rmrr_sanity_check(struct acpi_dmar_reserved_memory *rmrr)
{
--- a/drivers/iommu/intel/dmar.c
+++ b/drivers/iommu/intel/dmar.c
@@ -1606,9 +1606,9 @@ void qi_flush_pasid_cache(struct intel_i
*/
void dmar_disable_qi(struct intel_iommu *iommu)
{
+ ktime_t start_time = ktime_get();
unsigned long flags;
u32 sts;
- cycles_t start_time = get_cycles();
if (!ecap_qis(iommu->ecap))
return;
@@ -1624,7 +1624,7 @@ void dmar_disable_qi(struct intel_iommu
*/
while ((readl(iommu->reg + DMAR_IQT_REG) !=
readl(iommu->reg + DMAR_IQH_REG)) &&
- (DMAR_OPERATION_TIMEOUT > (get_cycles() - start_time)))
+ (DMAR_OPERATION_TIMEOUT > (ktime_get() - start_time)))
cpu_relax();
iommu->gcmd &= ~DMA_GCMD_QIE;
--- a/drivers/iommu/intel/iommu.h
+++ b/drivers/iommu/intel/iommu.h
@@ -23,6 +23,7 @@
#include <linux/xarray.h>
#include <linux/perf_event.h>
#include <linux/pci.h>
+#include <linux/timekeeping.h>
#include <linux/generic_pt/iommu.h>
#include <asm/iommu.h>
@@ -360,14 +361,17 @@
/* PERFINTRSTS_REG */
#define DMA_PERFINTRSTS_PIS ((u32)1)
+#define DMAR_OPERATION_TIMEOUT (((ktime_t)10) * NSEC_PER_SEC)
+
#define IOMMU_WAIT_OP(iommu, offset, op, cond, sts) \
do { \
- cycles_t start_time = get_cycles(); \
+ ktime_t start_time = ktime_get(); \
+ \
while (1) { \
sts = op(iommu->reg + offset); \
if (cond) \
break; \
- if (DMAR_OPERATION_TIMEOUT < (get_cycles() - start_time))\
+ if (DMAR_OPERATION_TIMEOUT < (ktime_get() - start_time))\
panic("DMAR hardware is malfunctioning\n"); \
cpu_relax(); \
} \
^ permalink raw reply
* [patch 10/38] arcnet: Remove function timing code
From: Thomas Gleixner @ 2026-04-10 12:19 UTC (permalink / raw)
To: LKML
Cc: Michael Grzeschik, netdev, Arnd Bergmann, x86, Lu Baolu, iommu,
linux-wireless, Herbert Xu, linux-crypto, Vlastimil Babka,
linux-mm, David Woodhouse, Bernie Thompson, linux-fbdev,
Theodore Tso, linux-ext4, Andrew Morton, Uladzislau Rezki,
Marco Elver, Dmitry Vyukov, kasan-dev, Andrey Ryabinin,
Thomas Sailer, linux-hams, Jason A. Donenfeld, Richard Henderson,
linux-alpha, Russell King, linux-arm-kernel, Catalin Marinas,
Huacai Chen, loongarch, Geert Uytterhoeven, linux-m68k,
Dinh Nguyen, Jonas Bonn, linux-openrisc, Helge Deller,
linux-parisc, Michael Ellerman, linuxppc-dev, Paul Walmsley,
linux-riscv, Heiko Carstens, linux-s390, David S. Miller,
sparclinux
In-Reply-To: <20260410120044.031381086@kernel.org>
ARCNET is a museums piece and the function timing can be done with
ftrace. Remove the cruft.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Cc: Michael Grzeschik <m.grzeschik@pengutronix.de>
Cc: netdev@vger.kernel.org
---
drivers/net/arcnet/arc-rimi.c | 4 ++--
drivers/net/arcnet/arcdevice.h | 20 +-------------------
drivers/net/arcnet/com20020.c | 6 ++----
drivers/net/arcnet/com90io.c | 6 ++----
drivers/net/arcnet/com90xx.c | 4 ++--
5 files changed, 9 insertions(+), 31 deletions(-)
--- a/drivers/net/arcnet/arc-rimi.c
+++ b/drivers/net/arcnet/arc-rimi.c
@@ -291,7 +291,7 @@ static void arcrimi_copy_to_card(struct
struct arcnet_local *lp = netdev_priv(dev);
void __iomem *memaddr = lp->mem_start + 0x800 + bufnum * 512 + offset;
- TIME(dev, "memcpy_toio", count, memcpy_toio(memaddr, buf, count));
+ memcpy_toio(memaddr, buf, count);
}
static void arcrimi_copy_from_card(struct net_device *dev, int bufnum,
@@ -300,7 +300,7 @@ static void arcrimi_copy_from_card(struc
struct arcnet_local *lp = netdev_priv(dev);
void __iomem *memaddr = lp->mem_start + 0x800 + bufnum * 512 + offset;
- TIME(dev, "memcpy_fromio", count, memcpy_fromio(buf, memaddr, count));
+ memcpy_fromio(buf, memaddr, count);
}
static int node;
--- a/drivers/net/arcnet/arcdevice.h
+++ b/drivers/net/arcnet/arcdevice.h
@@ -11,7 +11,6 @@
#ifndef _LINUX_ARCDEVICE_H
#define _LINUX_ARCDEVICE_H
-#include <asm/timex.h>
#include <linux/if_arcnet.h>
#ifdef __KERNEL__
@@ -62,7 +61,7 @@
#define D_RX 512 /* show rx packets */
#define D_SKB 1024 /* show skb's */
#define D_SKB_SIZE 2048 /* show skb sizes */
-#define D_TIMING 4096 /* show time needed to copy buffers to card */
+#define D_TIMING 4096 /* Not longer supported. Use tracing instead */
#define D_DEBUG 8192 /* Very detailed debug line for line */
#ifndef ARCNET_DEBUG_MAX
@@ -95,23 +94,6 @@ do { \
pr_cont(fmt, ##__VA_ARGS__); \
} while (0)
-/* see how long a function call takes to run, expressed in CPU cycles */
-#define TIME(dev, name, bytes, call) \
-do { \
- if (BUGLVL(D_TIMING)) { \
- unsigned long _x, _y; \
- _x = get_cycles(); \
- call; \
- _y = get_cycles(); \
- arc_printk(D_TIMING, dev, \
- "%s: %d bytes in %lu cycles == %lu Kbytes/100Mcycle\n", \
- name, bytes, _y - _x, \
- 100000000 / 1024 * bytes / (_y - _x + 1)); \
- } else { \
- call; \
- } \
-} while (0)
-
/*
* Time needed to reset the card - in ms (milliseconds). This works on my
* SMC PC100. I can't find a reference that tells me just how long I
--- a/drivers/net/arcnet/com20020.c
+++ b/drivers/net/arcnet/com20020.c
@@ -70,8 +70,7 @@ static void com20020_copy_from_card(stru
arcnet_outb(ofs & 0xff, ioaddr, COM20020_REG_W_ADDR_LO);
/* copy the data */
- TIME(dev, "insb", count,
- arcnet_insb(ioaddr, COM20020_REG_RW_MEMDATA, buf, count));
+ arcnet_insb(ioaddr, COM20020_REG_RW_MEMDATA, buf, count);
}
static void com20020_copy_to_card(struct net_device *dev, int bufnum,
@@ -84,8 +83,7 @@ static void com20020_copy_to_card(struct
arcnet_outb(ofs & 0xff, ioaddr, COM20020_REG_W_ADDR_LO);
/* copy the data */
- TIME(dev, "outsb", count,
- arcnet_outsb(ioaddr, COM20020_REG_RW_MEMDATA, buf, count));
+ arcnet_outsb(ioaddr, COM20020_REG_RW_MEMDATA, buf, count);
}
/* Reset the card and check some basic stuff during the detection stage. */
--- a/drivers/net/arcnet/com90io.c
+++ b/drivers/net/arcnet/com90io.c
@@ -332,15 +332,13 @@ static void com90io_setmask(struct net_d
static void com90io_copy_to_card(struct net_device *dev, int bufnum,
int offset, void *buf, int count)
{
- TIME(dev, "put_whole_buffer", count,
- put_whole_buffer(dev, bufnum * 512 + offset, count, buf));
+ put_whole_buffer(dev, bufnum * 512 + offset, count, buf);
}
static void com90io_copy_from_card(struct net_device *dev, int bufnum,
int offset, void *buf, int count)
{
- TIME(dev, "get_whole_buffer", count,
- get_whole_buffer(dev, bufnum * 512 + offset, count, buf));
+ get_whole_buffer(dev, bufnum * 512 + offset, count, buf);
}
static int io; /* use the insmod io= irq= shmem= options */
--- a/drivers/net/arcnet/com90xx.c
+++ b/drivers/net/arcnet/com90xx.c
@@ -633,7 +633,7 @@ static void com90xx_copy_to_card(struct
struct arcnet_local *lp = netdev_priv(dev);
void __iomem *memaddr = lp->mem_start + bufnum * 512 + offset;
- TIME(dev, "memcpy_toio", count, memcpy_toio(memaddr, buf, count));
+ memcpy_toio(memaddr, buf, count);
}
static void com90xx_copy_from_card(struct net_device *dev, int bufnum,
@@ -642,7 +642,7 @@ static void com90xx_copy_from_card(struc
struct arcnet_local *lp = netdev_priv(dev);
void __iomem *memaddr = lp->mem_start + bufnum * 512 + offset;
- TIME(dev, "memcpy_fromio", count, memcpy_fromio(buf, memaddr, count));
+ memcpy_fromio(buf, memaddr, count);
}
MODULE_DESCRIPTION("ARCnet COM90xx normal chipset driver");
^ permalink raw reply
* [patch 11/38] misc: sgi-gru: Remove get_cycles() [ab]use
From: Thomas Gleixner @ 2026-04-10 12:19 UTC (permalink / raw)
To: LKML
Cc: Arnd Bergmann, x86, Lu Baolu, iommu, Michael Grzeschik, netdev,
linux-wireless, Herbert Xu, linux-crypto, Vlastimil Babka,
linux-mm, David Woodhouse, Bernie Thompson, linux-fbdev,
Theodore Tso, linux-ext4, Andrew Morton, Uladzislau Rezki,
Marco Elver, Dmitry Vyukov, kasan-dev, Andrey Ryabinin,
Thomas Sailer, linux-hams, Jason A. Donenfeld, Richard Henderson,
linux-alpha, Russell King, linux-arm-kernel, Catalin Marinas,
Huacai Chen, loongarch, Geert Uytterhoeven, linux-m68k,
Dinh Nguyen, Jonas Bonn, linux-openrisc, Helge Deller,
linux-parisc, Michael Ellerman, linuxppc-dev, Paul Walmsley,
linux-riscv, Heiko Carstens, linux-s390, David S. Miller,
sparclinux
In-Reply-To: <20260410120044.031381086@kernel.org>
Calculating a timeout from get_cycles() is a historical leftover without
any functional requirement.
Use ktime_get() instead.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
---
drivers/misc/sgi-gru/gruhandles.c | 20 ++++++++------------
drivers/misc/sgi-gru/grukservices.c | 3 ++-
drivers/misc/sgi-gru/grutlbpurge.c | 5 ++---
3 files changed, 12 insertions(+), 16 deletions(-)
--- a/drivers/misc/sgi-gru/gruhandles.c
+++ b/drivers/misc/sgi-gru/gruhandles.c
@@ -6,26 +6,22 @@
*/
#include <linux/kernel.h>
+#include <linux/timekeeping.h>
#include "gru.h"
#include "grulib.h"
#include "grutables.h"
-/* 10 sec */
#include <linux/sync_core.h>
-#include <asm/tsc.h>
-#define GRU_OPERATION_TIMEOUT ((cycles_t) tsc_khz*10*1000)
-#define CLKS2NSEC(c) ((c) * 1000000 / tsc_khz)
+
+#define GRU_OPERATION_TIMEOUT_NSEC (((ktime_t)10 * NSEC_PER_SEC))
/* Extract the status field from a kernel handle */
#define GET_MSEG_HANDLE_STATUS(h) (((*(unsigned long *)(h)) >> 16) & 3)
struct mcs_op_statistic mcs_op_statistics[mcsop_last];
-static void update_mcs_stats(enum mcs_op op, unsigned long clks)
+static void update_mcs_stats(enum mcs_op op, unsigned long nsec)
{
- unsigned long nsec;
-
- nsec = CLKS2NSEC(clks);
atomic_long_inc(&mcs_op_statistics[op].count);
atomic_long_add(nsec, &mcs_op_statistics[op].total);
if (mcs_op_statistics[op].max < nsec)
@@ -58,21 +54,21 @@ static void report_instruction_timeout(v
static int wait_instruction_complete(void *h, enum mcs_op opc)
{
+ ktime_t start_time = ktime_get();
int status;
- unsigned long start_time = get_cycles();
while (1) {
cpu_relax();
status = GET_MSEG_HANDLE_STATUS(h);
if (status != CCHSTATUS_ACTIVE)
break;
- if (GRU_OPERATION_TIMEOUT < (get_cycles() - start_time)) {
+ if (GRU_OP_TIMEOUT_NSEC < (ktime_get() - start_time)) {
report_instruction_timeout(h);
- start_time = get_cycles();
+ start_time = ktime_get();
}
}
if (gru_options & OPT_STATS)
- update_mcs_stats(opc, get_cycles() - start_time);
+ update_mcs_stats(opc, (unsigned long)(ktime_get() - start_time));
return status;
}
--- a/drivers/misc/sgi-gru/grukservices.c
+++ b/drivers/misc/sgi-gru/grukservices.c
@@ -20,6 +20,7 @@
#include <linux/uaccess.h>
#include <linux/delay.h>
#include <linux/export.h>
+#include <linux/random.h>
#include <asm/io_apic.h>
#include "gru.h"
#include "grulib.h"
@@ -1106,7 +1107,7 @@ static int quicktest3(unsigned long arg)
int ret = 0;
memset(buf2, 0, sizeof(buf2));
- memset(buf1, get_cycles() & 255, sizeof(buf1));
+ memset(buf1, get_random_u32() & 255, sizeof(buf1));
gru_copy_gpa(uv_gpa(buf2), uv_gpa(buf1), BUFSIZE);
if (memcmp(buf1, buf2, BUFSIZE)) {
printk(KERN_DEBUG "GRU:%d quicktest3 error\n", smp_processor_id());
--- a/drivers/misc/sgi-gru/grutlbpurge.c
+++ b/drivers/misc/sgi-gru/grutlbpurge.c
@@ -22,13 +22,12 @@
#include <linux/delay.h>
#include <linux/timex.h>
#include <linux/srcu.h>
+#include <linux/random.h>
#include <asm/processor.h>
#include "gru.h"
#include "grutables.h"
#include <asm/uv/uv_hub.h>
-#define gru_random() get_cycles()
-
/* ---------------------------------- TLB Invalidation functions --------
* get_tgh_handle
*
@@ -49,7 +48,7 @@ static inline int get_off_blade_tgh(stru
int n;
n = GRU_NUM_TGH - gru->gs_tgh_first_remote;
- n = gru_random() % n;
+ n = get_random_u32() % n;
n += gru->gs_tgh_first_remote;
return n;
}
^ permalink raw reply
* [patch 12/38] wifi: wil6210: Replace get_cyles() usage
From: Thomas Gleixner @ 2026-04-10 12:19 UTC (permalink / raw)
To: LKML
Cc: linux-wireless, Arnd Bergmann, x86, Lu Baolu, iommu,
Michael Grzeschik, netdev, Herbert Xu, linux-crypto,
Vlastimil Babka, linux-mm, David Woodhouse, Bernie Thompson,
linux-fbdev, Theodore Tso, linux-ext4, Andrew Morton,
Uladzislau Rezki, Marco Elver, Dmitry Vyukov, kasan-dev,
Andrey Ryabinin, Thomas Sailer, linux-hams, Jason A. Donenfeld,
Richard Henderson, linux-alpha, Russell King, linux-arm-kernel,
Catalin Marinas, Huacai Chen, loongarch, Geert Uytterhoeven,
linux-m68k, Dinh Nguyen, Jonas Bonn, linux-openrisc, Helge Deller,
linux-parisc, Michael Ellerman, linuxppc-dev, Paul Walmsley,
linux-riscv, Heiko Carstens, linux-s390, David S. Miller,
sparclinux
In-Reply-To: <20260410120044.031381086@kernel.org>
There is no reason why this debug code requires to use get_cycles() for
timing purposes.
Use ktime_get() instead.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Cc: linux-wireless@vger.kernel.org
---
drivers/net/wireless/ath/wil6210/debugfs.c | 2 +-
drivers/net/wireless/ath/wil6210/txrx.c | 6 +++---
drivers/net/wireless/ath/wil6210/txrx_edma.c | 4 ++--
drivers/net/wireless/ath/wil6210/wil6210.h | 3 ++-
4 files changed, 8 insertions(+), 7 deletions(-)
--- a/drivers/net/wireless/ath/wil6210/debugfs.c
+++ b/drivers/net/wireless/ath/wil6210/debugfs.c
@@ -151,7 +151,7 @@ static int ring_show(struct seq_file *s,
char name[10];
char sidle[10];
/* performance monitoring */
- cycles_t now = get_cycles();
+ ktime_t now = ktime_get();
uint64_t idle = txdata->idle * 100;
uint64_t total = now - txdata->begin;
--- a/drivers/net/wireless/ath/wil6210/txrx.c
+++ b/drivers/net/wireless/ath/wil6210/txrx.c
@@ -1976,7 +1976,7 @@ static int __wil_tx_vring_tso(struct wil
used = wil_ring_used_tx(vring);
if (wil_val_in_range(wil->ring_idle_trsh,
used, used + descs_used)) {
- txdata->idle += get_cycles() - txdata->last_idle;
+ txdata->idle += ktime_get() - txdata->last_idle;
wil_dbg_txrx(wil, "Ring[%2d] not idle %d -> %d\n",
vring_index, used, used + descs_used);
}
@@ -2129,7 +2129,7 @@ static int __wil_tx_ring(struct wil6210_
used = wil_ring_used_tx(ring);
if (wil_val_in_range(wil->ring_idle_trsh,
used, used + nr_frags + 1)) {
- txdata->idle += get_cycles() - txdata->last_idle;
+ txdata->idle += ktime_get() - txdata->last_idle;
wil_dbg_txrx(wil, "Ring[%2d] not idle %d -> %d\n",
ring_index, used, used + nr_frags + 1);
}
@@ -2531,7 +2531,7 @@ int wil_tx_complete(struct wil6210_vif *
used_new, used_before_complete)) {
wil_dbg_txrx(wil, "Ring[%2d] idle %d -> %d\n",
ringid, used_before_complete, used_new);
- txdata->last_idle = get_cycles();
+ txdata->last_idle = ktime_get();
}
/* shall we wake net queues? */
--- a/drivers/net/wireless/ath/wil6210/txrx_edma.c
+++ b/drivers/net/wireless/ath/wil6210/txrx_edma.c
@@ -1286,7 +1286,7 @@ int wil_tx_sring_handler(struct wil6210_
used_new, used_before_complete)) {
wil_dbg_txrx(wil, "Ring[%2d] idle %d -> %d\n",
ring_id, used_before_complete, used_new);
- txdata->last_idle = get_cycles();
+ txdata->last_idle = ktime_get();
}
again:
@@ -1499,7 +1499,7 @@ static int __wil_tx_ring_tso_edma(struct
used = wil_ring_used_tx(ring);
if (wil_val_in_range(wil->ring_idle_trsh,
used, used + descs_used)) {
- txdata->idle += get_cycles() - txdata->last_idle;
+ txdata->idle += ktime_get() - txdata->last_idle;
wil_dbg_txrx(wil, "Ring[%2d] not idle %d -> %d\n",
ring_index, used, used + descs_used);
}
--- a/drivers/net/wireless/ath/wil6210/wil6210.h
+++ b/drivers/net/wireless/ath/wil6210/wil6210.h
@@ -14,6 +14,7 @@
#include <linux/timex.h>
#include <linux/types.h>
#include <linux/irqreturn.h>
+#include <linux/timekeeping.h>
#include "wmi.h"
#include "wil_platform.h"
#include "fw.h"
@@ -632,7 +633,7 @@ struct wil_txrx_ops {
struct wil_ring_tx_data {
bool dot1x_open;
int enabled;
- cycles_t idle, last_idle, begin;
+ ktime_t idle, last_idle, begin;
u8 agg_wsize; /* agreed aggregation window, 0 - no agg */
u16 agg_timeout;
u8 agg_amsdu;
^ permalink raw reply
* Re: [PATCH v3 0/4] mm: improve large folio readahead and alignment for exec memory
From: Usama Arif @ 2026-04-10 12:19 UTC (permalink / raw)
To: Lorenzo Stoakes
Cc: Andrew Morton, david, willy, ryan.roberts, linux-mm, r, jack, ajd,
apopple, baohua, baolin.wang, brauner, catalin.marinas, dev.jain,
kees, kevin.brodsky, lance.yang, Liam.Howlett, linux-arm-kernel,
linux-fsdevel, linux-kernel, mhocko, npache, pasha.tatashin,
rmclure, rppt, surenb, vbabka, Al Viro, ziy, hannes, kas,
shakeel.butt, leitao, kernel-team
In-Reply-To: <adjllNan2vgBNBHJ@lucifer>
On 10/04/2026 12:57, Lorenzo Stoakes wrote:
> On Fri, Apr 10, 2026 at 12:55:42PM +0100, Lorenzo Stoakes wrote:
>> On Fri, Apr 10, 2026 at 12:03:03PM +0100, Usama Arif wrote:
>>>
>>>
>>> On 02/04/2026 19:08, Usama Arif wrote:
>>>> v2 -> v3: https://lore.kernel.org/all/20260320140315.979307-1-usama.arif@linux.dev/
>>>> - Take into account READ_ONLY_THP_FOR_FS for elf alignment by aligning
>>>> to HPAGE_PMD_SIZE limited to 2M (Rui)
>>>> - Reviewed-by tags for patch 1 from Kiryl and Jan
>>>> - Remove preferred_exec_order() (Jan)
>>>> - Change ra->order to HPAGE_PMD_ORDER if vma_pages(vma) >= HPAGE_PMD_NR
>>>> otherwise use exec_folio_order() with gfp &= ~__GFP_RECLAIM for
>>>> do_sync_mmap_readahead().
>>>> - Change exec_folio_order() to return 2M (cont-pte size) for 64K base
>>>> page size for arm64.
>>>> - remove bprm->file NULL check (Matthew)
>>>> - Change filp to file (Matthew)
>>>> - Improve checking of p_vaddr and p_vaddr (Rui and Matthew)
>>>>
>>>
>>> Hello!
>>>
>>> Just wanted to check if there was any feedback/review on the latest
>>> revision?
>>
>> It's -rc7, this is definitely something for next cycle :)
>>
>> On my part, my upstream bandwidth has drastically reduced, and review is
>> probably going to have to be a hobbyist thing at least for now.
>>
>> Also, not to be mean but:
>>
>> $ git log -E -i --grep "(Reviewed|Acked)-by: Usama Arif" --oneline | wc -l
>> 21
>>
>> So... :)
>>
>> Review in mm is very lop-sided, let's try to balance it out a bit!
>>
>>>
>>> Thanks!
>>>
>>
>> Thanks, Lorenzo
>
> (Note that we're in a 'quiet period' from here until -rc1 of next cycle and
> won't be taking anything new until then. We plan to do this from around rc5 or
> rc6 of each cycle in future).
Thanks! Just wanted to check, as I am always confused about this. Is it ok
to send patches for review for next release at this time? So that they
are in a good state when rc1 comes. I wanted to send PMD swap entries
for review after I am finished testing, but I want them for review for
next release.
^ permalink raw reply
* [patch 13/38] crypto: tcrypt: Replace get_cycles() with ktime_get()
From: Thomas Gleixner @ 2026-04-10 12:19 UTC (permalink / raw)
To: LKML
Cc: Herbert Xu, linux-crypto, Arnd Bergmann, x86, Lu Baolu, iommu,
Michael Grzeschik, netdev, linux-wireless, Vlastimil Babka,
linux-mm, David Woodhouse, Bernie Thompson, linux-fbdev,
Theodore Tso, linux-ext4, Andrew Morton, Uladzislau Rezki,
Marco Elver, Dmitry Vyukov, kasan-dev, Andrey Ryabinin,
Thomas Sailer, linux-hams, Jason A. Donenfeld, Richard Henderson,
linux-alpha, Russell King, linux-arm-kernel, Catalin Marinas,
Huacai Chen, loongarch, Geert Uytterhoeven, linux-m68k,
Dinh Nguyen, Jonas Bonn, linux-openrisc, Helge Deller,
linux-parisc, Michael Ellerman, linuxppc-dev, Paul Walmsley,
linux-riscv, Heiko Carstens, linux-s390, David S. Miller,
sparclinux
In-Reply-To: <20260410120044.031381086@kernel.org>
get_cycles() is the historical access to a fine grained time source, but it
is a suboptimal choice for two reasons:
- get_cycles() is not guaranteed to be supported and functional on all
systems/platforms. If not supported or not functional it returns 0,
which makes benchmarking moot.
- get_cycles() returns the raw counter value of whatever the
architecture platform provides. The original x86 Time Stamp Counter
(TSC) was despite its name tied to the actual CPU core frequency.
That's not longer the case. So the counter value is only meaningful
when the CPU operates at the same frequency as the TSC or the value is
adjusted to the actual CPU frequency. Other architectures and
platforms provide similar disjunct counters via get_cycles(), so the
result is operations per BOGO-cycles, which is not really meaningful.
Use ktime_get() instead which provides nanosecond timestamps with the
granularity of the underlying hardware counter, which is not different to
the variety of get_cycles() implementations.
This provides at least understandable metrics, i.e. operations/nanoseconds,
and is available on all platforms. As with get_cycles() the result might
have to be put into relation with the CPU operating frequency, but that's
not any different.
This is part of a larger effort to remove get_cycles() usage from
non-architecture code.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: linux-crypto@vger.kernel.org
---
crypto/tcrypt.c | 84 ++++++++++++++++++++++++++++----------------------------
1 file changed, 42 insertions(+), 42 deletions(-)
--- a/crypto/tcrypt.c
+++ b/crypto/tcrypt.c
@@ -202,7 +202,7 @@ static int test_mb_aead_jiffies(struct t
static int test_mb_aead_cycles(struct test_mb_aead_data *data, int enc,
int blen, u32 num_mb)
{
- unsigned long cycles = 0;
+ unsigned long nsecs = 0;
int ret = 0;
int i;
int *rc;
@@ -220,20 +220,20 @@ static int test_mb_aead_cycles(struct te
/* The real thing. */
for (i = 0; i < 8; i++) {
- cycles_t start, end;
+ ktime_t start, end;
- start = get_cycles();
+ start = ktime_get();
ret = do_mult_aead_op(data, enc, num_mb, rc);
- end = get_cycles();
+ end = ktime_get();
if (ret)
goto out;
- cycles += end - start;
+ nsecs += (unsigned long)(end - start);
}
- pr_cont("1 operation in %lu cycles (%d bytes)\n",
- (cycles + 4) / (8 * num_mb), blen);
+ pr_cont("1 operation in %lu nsecs (%d bytes)\n",
+ nsecs / (8 * num_mb), blen);
out:
kfree(rc);
@@ -475,7 +475,7 @@ static int test_aead_jiffies(struct aead
static int test_aead_cycles(struct aead_request *req, int enc, int blen)
{
- unsigned long cycles = 0;
+ unsigned long nsecs = 0;
int ret = 0;
int i;
@@ -492,25 +492,24 @@ static int test_aead_cycles(struct aead_
/* The real thing. */
for (i = 0; i < 8; i++) {
- cycles_t start, end;
+ ktime_t start, end;
- start = get_cycles();
+ start = ktime_get();
if (enc)
ret = do_one_aead_op(req, crypto_aead_encrypt(req));
else
ret = do_one_aead_op(req, crypto_aead_decrypt(req));
- end = get_cycles();
+ end = ktime_get();
if (ret)
goto out;
- cycles += end - start;
+ nsecs += (unsigned long)(end - start);
}
out:
if (ret == 0)
- pr_cont("1 operation in %lu cycles (%d bytes)\n",
- (cycles + 4) / 8, blen);
+ pr_cont("1 operation in %lu nsecs (%d bytes)\n", nsecs / 8, blen);
return ret;
}
@@ -771,7 +770,7 @@ static int test_ahash_jiffies(struct aha
static int test_ahash_cycles_digest(struct ahash_request *req, int blen,
char *out)
{
- unsigned long cycles = 0;
+ unsigned long nsecs = 0;
int ret, i;
/* Warm-up run. */
@@ -783,25 +782,25 @@ static int test_ahash_cycles_digest(stru
/* The real thing. */
for (i = 0; i < 8; i++) {
- cycles_t start, end;
+ ktime_t start, end;
- start = get_cycles();
+ start = ktime_get();
ret = do_one_ahash_op(req, crypto_ahash_digest(req));
if (ret)
goto out;
- end = get_cycles();
+ end = ktime_get();
- cycles += end - start;
+ nsecs += (unsigned long)(end - start);
}
out:
if (ret)
return ret;
- pr_cont("%6lu cycles/operation, %4lu cycles/byte\n",
- cycles / 8, cycles / (8 * blen));
+ pr_cont("%6lu nsecs/operation, %4lu nsecs/byte\n",
+ nsecs / 8, nsecs / (8 * blen));
return 0;
}
@@ -809,7 +808,7 @@ static int test_ahash_cycles_digest(stru
static int test_ahash_cycles(struct ahash_request *req, int blen,
int plen, char *out)
{
- unsigned long cycles = 0;
+ unsigned long nsecs = 0;
int i, pcount, ret;
if (plen == blen)
@@ -832,9 +831,9 @@ static int test_ahash_cycles(struct ahas
/* The real thing. */
for (i = 0; i < 8; i++) {
- cycles_t start, end;
+ ktime_t start, end;
- start = get_cycles();
+ start = ktime_get();
ret = do_one_ahash_op(req, crypto_ahash_init(req));
if (ret)
@@ -848,17 +847,17 @@ static int test_ahash_cycles(struct ahas
if (ret)
goto out;
- end = get_cycles();
+ end = ktime_get();
- cycles += end - start;
+ nsecs += (unsigned long)(end - start);
}
out:
if (ret)
return ret;
- pr_cont("%6lu cycles/operation, %4lu cycles/byte\n",
- cycles / 8, cycles / (8 * blen));
+ pr_cont("%6lu nsecs/operation, %4lu nsecs/byte\n",
+ nsecs / 8, nsecs / (8 * blen));
return 0;
}
@@ -1019,7 +1018,7 @@ static int test_mb_acipher_jiffies(struc
static int test_mb_acipher_cycles(struct test_mb_skcipher_data *data, int enc,
int blen, u32 num_mb)
{
- unsigned long cycles = 0;
+ unsigned long nsecs = 0;
int ret = 0;
int i;
int *rc;
@@ -1037,20 +1036,20 @@ static int test_mb_acipher_cycles(struct
/* The real thing. */
for (i = 0; i < 8; i++) {
- cycles_t start, end;
+ ktime_t start, end;
- start = get_cycles();
+ start = ktime_get();
ret = do_mult_acipher_op(data, enc, num_mb, rc);
- end = get_cycles();
+ end = ktime_get();
if (ret)
goto out;
- cycles += end - start;
+ nsecs += (unsigned long)(end - start);
}
- pr_cont("1 operation in %lu cycles (%d bytes)\n",
- (cycles + 4) / (8 * num_mb), blen);
+ pr_cont("1 operation in %lu nsecs (%d bytes)\n",
+ nsecs / (8 * num_mb), blen);
out:
kfree(rc);
@@ -1246,7 +1245,7 @@ static int test_acipher_jiffies(struct s
static int test_acipher_cycles(struct skcipher_request *req, int enc,
int blen)
{
- unsigned long cycles = 0;
+ unsigned long nsecs = 0;
int ret = 0;
int i;
@@ -1265,27 +1264,28 @@ static int test_acipher_cycles(struct sk
/* The real thing. */
for (i = 0; i < 8; i++) {
- cycles_t start, end;
+ ktime_t start, end;
+
+ start = ktime_get();
- start = get_cycles();
if (enc)
ret = do_one_acipher_op(req,
crypto_skcipher_encrypt(req));
else
ret = do_one_acipher_op(req,
crypto_skcipher_decrypt(req));
- end = get_cycles();
+ end = ktime_get();
if (ret)
goto out;
- cycles += end - start;
+ nsecs += (unsigned long)(end - start);
}
out:
if (ret == 0)
- pr_cont("1 operation in %lu cycles (%d bytes)\n",
- (cycles + 4) / 8, blen);
+ pr_cont("1 operation in %lu nsecs (%d bytes)\n",
+ nsecs / 8, blen);
return ret;
}
^ permalink raw reply
* [patch 14/38] slub: Use prandom instead of get_cycles()
From: Thomas Gleixner @ 2026-04-10 12:19 UTC (permalink / raw)
To: LKML
Cc: Vlastimil Babka, linux-mm, Arnd Bergmann, x86, Lu Baolu, iommu,
Michael Grzeschik, netdev, linux-wireless, Herbert Xu,
linux-crypto, David Woodhouse, Bernie Thompson, linux-fbdev,
Theodore Tso, linux-ext4, Andrew Morton, Uladzislau Rezki,
Marco Elver, Dmitry Vyukov, kasan-dev, Andrey Ryabinin,
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linux-alpha, Russell King, linux-arm-kernel, Catalin Marinas,
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Dinh Nguyen, Jonas Bonn, linux-openrisc, Helge Deller,
linux-parisc, Michael Ellerman, linuxppc-dev, Paul Walmsley,
linux-riscv, Heiko Carstens, linux-s390, David S. Miller,
sparclinux
In-Reply-To: <20260410120044.031381086@kernel.org>
The decision whether to scan remote nodes is based on a 'random' number
retrieved via get_cycles(). get_cycles() is about to be removed.
There is already prandom state in the code, so use that instead.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: linux-mm@kvack.org
---
mm/slub.c | 37 +++++++++++++++++++++++--------------
1 file changed, 23 insertions(+), 14 deletions(-)
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -3302,6 +3302,25 @@ static inline struct slab *alloc_slab_pa
return slab;
}
+#if defined(CONFIG_SLAB_FREELIST_RANDOM) || defined(CONFIG_NUMA)
+static DEFINE_PER_CPU(struct rnd_state, slab_rnd_state);
+
+static unsigned int slab_get_prandom_state(unsigned int limit)
+{
+ struct rnd_state *state;
+ unsigned int res;
+
+ /*
+ * An interrupt or NMI handler might interrupt and change
+ * the state in the middle, but that's safe.
+ */
+ state = &get_cpu_var(slab_rnd_state);
+ res = prandom_u32_state(state) % limit;
+ put_cpu_var(slab_rnd_state);
+ return res;
+}
+#endif
+
#ifdef CONFIG_SLAB_FREELIST_RANDOM
/* Pre-initialize the random sequence cache */
static int init_cache_random_seq(struct kmem_cache *s)
@@ -3365,8 +3384,6 @@ static void *next_freelist_entry(struct
return (char *)start + idx;
}
-static DEFINE_PER_CPU(struct rnd_state, slab_rnd_state);
-
/* Shuffle the single linked freelist based on a random pre-computed sequence */
static bool shuffle_freelist(struct kmem_cache *s, struct slab *slab,
bool allow_spin)
@@ -3383,15 +3400,7 @@ static bool shuffle_freelist(struct kmem
if (allow_spin) {
pos = get_random_u32_below(freelist_count);
} else {
- struct rnd_state *state;
-
- /*
- * An interrupt or NMI handler might interrupt and change
- * the state in the middle, but that's safe.
- */
- state = &get_cpu_var(slab_rnd_state);
- pos = prandom_u32_state(state) % freelist_count;
- put_cpu_var(slab_rnd_state);
+ pos = slab_get_prandom_state(freelist_count);
}
page_limit = slab->objects * s->size;
@@ -3882,7 +3891,7 @@ static void *get_from_any_partial(struct
* with available objects.
*/
if (!s->remote_node_defrag_ratio ||
- get_cycles() % 1024 > s->remote_node_defrag_ratio)
+ slab_get_prandom_state(1024) > s->remote_node_defrag_ratio)
return NULL;
do {
@@ -7102,7 +7111,7 @@ static unsigned int
/* see get_from_any_partial() for the defrag ratio description */
if (!s->remote_node_defrag_ratio ||
- get_cycles() % 1024 > s->remote_node_defrag_ratio)
+ slab_get_prandom_state(1024) > s->remote_node_defrag_ratio)
return 0;
do {
@@ -8421,7 +8430,7 @@ void __init kmem_cache_init_late(void)
flushwq = alloc_workqueue("slub_flushwq", WQ_MEM_RECLAIM | WQ_PERCPU,
0);
WARN_ON(!flushwq);
-#ifdef CONFIG_SLAB_FREELIST_RANDOM
+#if defined(CONFIG_SLAB_FREELIST_RANDOM) || defined(CONFIG_NUMA)
prandom_init_once(&slab_rnd_state);
#endif
}
^ permalink raw reply
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