From: David Gibson <dwg@au1.ibm.com>
To: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org, paulus@samba.org, linux-mm@kvack.org
Subject: Re: [PATCH -V5 17/25] powerpc/THP: Implement transparent hugepages for ppc64
Date: Fri, 12 Apr 2013 15:39:47 +1000 [thread overview]
Message-ID: <20130412053947.GI5065@truffula.fritz.box> (raw)
In-Reply-To: <8761zsmj65.fsf@linux.vnet.ibm.com>
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On Fri, Apr 12, 2013 at 10:36:58AM +0530, Aneesh Kumar K.V wrote:
> David Gibson <dwg@au1.ibm.com> writes:
>
> > On Thu, Apr 11, 2013 at 01:10:29PM +0530, Aneesh Kumar K.V wrote:
> >> David Gibson <dwg@au1.ibm.com> writes:
> >>
> >> > On Thu, Apr 04, 2013 at 11:27:55AM +0530, Aneesh Kumar K.V wrote:
> >> >> From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
> >> >>
> >> >> We now have pmd entries covering to 16MB range. To implement THP on powerpc,
> >> >> we double the size of PMD. The second half is used to deposit the pgtable (PTE page).
> >> >> We also use the depoisted PTE page for tracking the HPTE information. The information
> >> >> include [ secondary group | 3 bit hidx | valid ]. We use one byte per each HPTE entry.
> >> >> With 16MB hugepage and 64K HPTE we need 256 entries and with 4K HPTE we need
> >> >> 4096 entries. Both will fit in a 4K PTE page.
> >> >>
> >> >> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
> >> >> ---
> >> >> arch/powerpc/include/asm/page.h | 2 +-
> >> >> arch/powerpc/include/asm/pgtable-ppc64-64k.h | 3 +-
> >> >> arch/powerpc/include/asm/pgtable-ppc64.h | 2 +-
> >> >> arch/powerpc/include/asm/pgtable.h | 240 ++++++++++++++++++++
> >> >> arch/powerpc/mm/pgtable.c | 314 ++++++++++++++++++++++++++
> >> >> arch/powerpc/mm/pgtable_64.c | 13 ++
> >> >> arch/powerpc/platforms/Kconfig.cputype | 1 +
> >> >> 7 files changed, 572 insertions(+), 3 deletions(-)
> >> >>
> >> >> diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include/asm/page.h
> >> >> index 38e7ff6..b927447 100644
> >> >> --- a/arch/powerpc/include/asm/page.h
> >> >> +++ b/arch/powerpc/include/asm/page.h
> >> >> @@ -40,7 +40,7 @@
> >> >> #ifdef CONFIG_HUGETLB_PAGE
> >> >> extern unsigned int HPAGE_SHIFT;
> >> >> #else
> >> >> -#define HPAGE_SHIFT PAGE_SHIFT
> >> >> +#define HPAGE_SHIFT PMD_SHIFT
> >> >
> >> > That looks like it could break everything except the 64k page size
> >> > 64-bit base.
> >>
> >> How about
> >
> > It seems very dubious to me to have transparent hugepages enabled
> > without explicit hugepages in the first place.
> >
>
> IMHO once we have THP, we will not be using explicit hugepages unless we
> want 16GB pages.
We still can't go breaking the combination in the interim. Especially
if users are already in the habit of invoking things with
libhugetlbfs.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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next prev parent reply other threads:[~2013-04-12 5:53 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-04 5:57 [PATCH -V5 00/25] THP support for PPC64 Aneesh Kumar K.V
2013-04-04 5:57 ` [PATCH -V5 01/25] powerpc: Use signed formatting when printing error Aneesh Kumar K.V
2013-04-04 5:57 ` [PATCH -V5 02/25] powerpc: Save DAR and DSISR in pt_regs on MCE Aneesh Kumar K.V
2013-04-04 5:57 ` [PATCH -V5 03/25] powerpc: Don't hard code the size of pte page Aneesh Kumar K.V
2013-04-04 5:57 ` [PATCH -V5 04/25] powerpc: Reduce the PTE_INDEX_SIZE Aneesh Kumar K.V
2013-04-11 7:10 ` David Gibson
2013-04-04 5:57 ` [PATCH -V5 05/25] powerpc: Move the pte free routines from common header Aneesh Kumar K.V
2013-04-04 5:57 ` [PATCH -V5 06/25] powerpc: Reduce PTE table memory wastage Aneesh Kumar K.V
2013-04-10 4:46 ` David Gibson
2013-04-10 6:29 ` Aneesh Kumar K.V
2013-04-10 7:04 ` David Gibson
2013-04-10 7:53 ` Aneesh Kumar K.V
2013-04-10 17:47 ` Aneesh Kumar K.V
2013-04-11 1:20 ` David Gibson
2013-04-11 1:12 ` David Gibson
2013-04-10 7:14 ` Michael Ellerman
2013-04-10 7:54 ` Aneesh Kumar K.V
2013-04-10 8:52 ` Aneesh Kumar K.V
2013-04-04 5:57 ` [PATCH -V5 07/25] powerpc: Use encode avpn where we need only avpn values Aneesh Kumar K.V
2013-04-04 5:57 ` [PATCH -V5 08/25] powerpc: Decode the pte-lp-encoding bits correctly Aneesh Kumar K.V
2013-04-10 7:19 ` David Gibson
2013-04-10 8:11 ` Aneesh Kumar K.V
2013-04-10 17:49 ` Aneesh Kumar K.V
2013-04-11 1:28 ` David Gibson
2013-04-04 5:57 ` [PATCH -V5 09/25] powerpc: Fix hpte_decode to use the correct decoding for page sizes Aneesh Kumar K.V
2013-04-11 3:20 ` David Gibson
2013-04-04 5:57 ` [PATCH -V5 10/25] powerpc: print both base and actual page size on hash failure Aneesh Kumar K.V
2013-04-11 3:21 ` David Gibson
2013-04-04 5:57 ` [PATCH -V5 11/25] powerpc: Print page size info during boot Aneesh Kumar K.V
2013-04-04 5:57 ` [PATCH -V5 12/25] powerpc: Return all the valid pte ecndoing in KVM_PPC_GET_SMMU_INFO ioctl Aneesh Kumar K.V
2013-04-11 3:24 ` David Gibson
2013-04-11 5:11 ` Aneesh Kumar K.V
2013-04-11 5:57 ` David Gibson
2013-04-04 5:57 ` [PATCH -V5 13/25] powerpc: Update tlbie/tlbiel as per ISA doc Aneesh Kumar K.V
2013-04-11 3:30 ` David Gibson
2013-04-11 5:20 ` Aneesh Kumar K.V
2013-04-11 6:16 ` David Gibson
2013-04-11 6:36 ` Aneesh Kumar K.V
2013-04-04 5:57 ` [PATCH -V5 14/25] mm/THP: HPAGE_SHIFT is not a #define on some arch Aneesh Kumar K.V
2013-04-11 3:36 ` David Gibson
2013-04-04 5:57 ` [PATCH -V5 15/25] mm/THP: Add pmd args to pgtable deposit and withdraw APIs Aneesh Kumar K.V
2013-04-11 3:40 ` David Gibson
2013-04-04 5:57 ` [PATCH -V5 16/25] mm/THP: withdraw the pgtable after pmdp related operations Aneesh Kumar K.V
2013-04-04 5:57 ` [PATCH -V5 17/25] powerpc/THP: Implement transparent hugepages for ppc64 Aneesh Kumar K.V
2013-04-11 5:38 ` David Gibson
2013-04-11 7:40 ` Aneesh Kumar K.V
2013-04-12 0:51 ` David Gibson
2013-04-12 5:06 ` Aneesh Kumar K.V
2013-04-12 5:39 ` David Gibson [this message]
2013-04-04 5:57 ` [PATCH -V5 18/25] powerpc/THP: Double the PMD table size for THP Aneesh Kumar K.V
2013-04-11 6:18 ` David Gibson
2013-04-04 5:57 ` [PATCH -V5 19/25] powerpc/THP: Differentiate THP PMD entries from HUGETLB PMD entries Aneesh Kumar K.V
2013-04-10 7:21 ` Michael Ellerman
2013-04-10 18:26 ` Aneesh Kumar K.V
2013-04-12 1:28 ` David Gibson
2013-04-04 5:57 ` [PATCH -V5 20/25] powerpc/THP: Add code to handle HPTE faults for large pages Aneesh Kumar K.V
2013-04-12 4:01 ` David Gibson
2013-04-04 5:57 ` [PATCH -V5 21/25] powerpc: Handle hugepage in perf callchain Aneesh Kumar K.V
2013-04-12 1:34 ` David Gibson
2013-04-12 5:05 ` Aneesh Kumar K.V
2013-04-04 5:58 ` [PATCH -V5 22/25] powerpc/THP: get_user_pages_fast changes Aneesh Kumar K.V
2013-04-12 1:41 ` David Gibson
2013-04-04 5:58 ` [PATCH -V5 23/25] powerpc/THP: Enable THP on PPC64 Aneesh Kumar K.V
2013-04-04 5:58 ` [PATCH -V5 24/25] powerpc: Optimize hugepage invalidate Aneesh Kumar K.V
2013-04-12 4:21 ` David Gibson
2013-04-14 10:02 ` Aneesh Kumar K.V
2013-04-15 1:18 ` David Gibson
2013-04-04 5:58 ` [PATCH -V5 25/25] powerpc: Handle hugepages in kvm Aneesh Kumar K.V
2013-04-04 6:00 ` [PATCH -V5 00/25] THP support for PPC64 Simon Jeons
2013-04-04 6:10 ` Aneesh Kumar K.V
2013-04-04 6:14 ` Simon Jeons
2013-04-04 8:38 ` Aneesh Kumar K.V
2013-04-19 1:55 ` Simon Jeons
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