From: Pavel Machek <pavel@denx.de>
To: Sasha Levin <sashal@kernel.org>
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, 16 Jan 2024 21:44:01 +0100 [thread overview]
Message-ID: <ZabqkZ2vXaicy3pZ@duo.ucw.cz> (raw)
In-Reply-To: <20240115232818.210010-9-sashal@kernel.org>
[-- Attachment #1: Type: text/plain, Size: 1132 bytes --]
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.
BR,
Pavel
--
DENX Software Engineering GmbH, Managing Director: Erika Unter
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 195 bytes --]
next prev parent reply other threads:[~2024-01-16 20:44 UTC|newest]
Thread overview: 13+ 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 ` [PATCH AUTOSEL 5.10 03/10] drivers/perf: pmuv3: don't expose SW_INCR event in sysfs 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 ` [PATCH AUTOSEL 5.10 05/10] powerpc/mm: Fix build failures due to arch_reserved_kernel_pages() 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 ` [PATCH AUTOSEL 5.10 08/10] powerpc/lib: Validate size for vector operations 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 [this message]
2024-01-30 20:58 ` Sasha Levin
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=ZabqkZ2vXaicy3pZ@duo.ucw.cz \
--to=pavel@denx.de \
--cc=acdunlap@google.com \
--cc=aik@amd.com \
--cc=ashok.raj@intel.com \
--cc=babu.moger@amd.com \
--cc=bp@alien8.de \
--cc=brgerst@gmail.com \
--cc=daniel.sneddon@linux.intel.com \
--cc=dave.hansen@linux.intel.com \
--cc=jmattson@google.com \
--cc=jpoimboe@kernel.org \
--cc=kim.phillips@amd.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=mjguzik@gmail.com \
--cc=nik.borisov@suse.com \
--cc=peterz@infradead.org \
--cc=puwen@hygon.cn \
--cc=reinette.chatre@intel.com \
--cc=rick.p.edgecombe@intel.com \
--cc=sashal@kernel.org \
--cc=seanjc@google.com \
--cc=stable@vger.kernel.org \
--cc=tglx@linutronix.de \
--cc=vegard.nossum@oracle.com \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®