From: Sasha Levin <sashal@kernel.org>
To: Pavel Machek <pavel@denx.de>
Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org,
"Borislav Petkov (AMD)" <bp@alien8.de>,
tglx@linutronix.de, mingo@redhat.com,
dave.hansen@linux.intel.com, x86@kernel.org, puwen@hygon.cn,
seanjc@google.com, kim.phillips@amd.com,
reinette.chatre@intel.com, babu.moger@amd.com,
jmattson@google.com, peterz@infradead.org, ashok.raj@intel.com,
rick.p.edgecombe@intel.com, brgerst@gmail.com, mjguzik@gmail.com,
jpoimboe@kernel.org, nik.borisov@suse.com, aik@amd.com,
vegard.nossum@oracle.com, daniel.sneddon@linux.intel.com,
acdunlap@google.com
Subject: Re: [PATCH AUTOSEL 5.10 09/10] x86/barrier: Do not serialize MSR accesses on AMD
Date: Tue, 30 Jan 2024 15:58:21 -0500 [thread overview]
Message-ID: <Zbli7QIGVFT8EtO4@sashalap> (raw)
In-Reply-To: <ZabqkZ2vXaicy3pZ@duo.ucw.cz>
On Tue, Jan 16, 2024 at 09:44:01PM +0100, Pavel Machek wrote:
>Hi!
>
>> From: "Borislav Petkov (AMD)" <bp@alien8.de>
>>
>> [ Upstream commit 04c3024560d3a14acd18d0a51a1d0a89d29b7eb5 ]
>>
>> AMD does not have the requirement for a synchronization barrier when
>> acccessing a certain group of MSRs. Do not incur that unnecessary
>> penalty there.
>...
>> Performance captured using an unmodified ipi-bench using the 'mesh-ipi' option
>> with and without weak_wrmsr_fence() on a Zen4 system also showed significant
>> performance improvement without weak_wrmsr_fence(). The 'mesh-ipi' option ignores
>> CCX or CCD and just picks random vCPU.
>>
>> Average throughput (10 iterations) with weak_wrmsr_fence(),
>> Cumulative throughput: 4933374 IPI/s
>>
>> Average throughput (10 iterations) without weak_wrmsr_fence(),
>> Cumulative throughput: 6355156 IPI/s
>>
>> [1] https://github.com/bytedance/kvm-utils/tree/master/microbenchmark/ipi-bench
>
>Speed improvement, not a bugfix. Please drop.
Dropped, thanks!
--
Thanks,
Sasha
next prev parent reply other threads:[~2024-01-30 20:58 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-15 23:27 [PATCH AUTOSEL 5.10 01/10] watch_queue: fix kcalloc() arguments order Sasha Levin
2024-01-15 23:27 ` [PATCH AUTOSEL 5.10 02/10] powerpc/mm: Fix null-pointer dereference in pgtable_cache_add Sasha Levin
2024-01-15 23:27 ` Sasha Levin
2024-01-15 23:27 ` [PATCH AUTOSEL 5.10 03/10] drivers/perf: pmuv3: don't expose SW_INCR event in sysfs Sasha Levin
2024-01-15 23:27 ` Sasha Levin
2024-01-15 23:27 ` [PATCH AUTOSEL 5.10 04/10] powerpc: Fix build error due to is_valid_bugaddr() Sasha Levin
2024-01-15 23:27 ` Sasha Levin
2024-01-15 23:27 ` [PATCH AUTOSEL 5.10 05/10] powerpc/mm: Fix build failures due to arch_reserved_kernel_pages() Sasha Levin
2024-01-15 23:27 ` Sasha Levin
2024-01-15 23:27 ` [PATCH AUTOSEL 5.10 06/10] x86/boot: Ignore NMIs during very early boot Sasha Levin
2024-01-15 23:27 ` [PATCH AUTOSEL 5.10 07/10] powerpc: pmd_move_must_withdraw() is only needed for CONFIG_TRANSPARENT_HUGEPAGE Sasha Levin
2024-01-15 23:27 ` Sasha Levin
2024-01-15 23:27 ` [PATCH AUTOSEL 5.10 08/10] powerpc/lib: Validate size for vector operations Sasha Levin
2024-01-15 23:27 ` Sasha Levin
2024-01-15 23:27 ` [PATCH AUTOSEL 5.10 09/10] x86/barrier: Do not serialize MSR accesses on AMD Sasha Levin
2024-01-16 20:44 ` Pavel Machek
2024-01-30 20:58 ` Sasha Levin [this message]
2024-01-15 23:27 ` [PATCH AUTOSEL 5.10 10/10] x86/mce: Mark fatal MCE's page as poison to avoid panic in the kdump kernel Sasha Levin
2024-01-16 20:43 ` [PATCH AUTOSEL 5.10 01/10] watch_queue: fix kcalloc() arguments order Pavel Machek
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