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From: Christoph Hellwig <hch@lst.de>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Christoph Hellwig <hch@lst.de>,
	Andrew Morton <akpm@linux-foundation.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>, Ard Biesheuvel <ardb@kernel.org>,
	Huacai Chen <chenhuacai@kernel.org>,
	WANG Xuerui <kernel@xen0n.name>,
	Madhavan Srinivasan <maddy@linux.ibm.com>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Nicholas Piggin <npiggin@gmail.com>,
	"Christophe Leroy (CS GROUP)" <chleroy@kernel.org>,
	Paul Walmsley <pjw@kernel.org>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Alexandre Ghiti <alex@ghiti.fr>,
	Heiko Carstens <hca@linux.ibm.com>,
	Vasily Gorbik <gor@linux.ibm.com>,
	Alexander Gordeev <agordeev@linux.ibm.com>,
	Christian Borntraeger <borntraeger@linux.ibm.com>,
	Sven Schnelle <svens@linux.ibm.com>,
	Thomas Gleixner <tglx@kernel.org>, Ingo Molnar <mingo@redhat.com>,
	Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	x86@kernel.org, Herbert Xu <herbert@gondor.apana.org.au>,
	Dan Williams <dan.j.williams@intel.com>, Chris Mason <clm@fb.com>,
	David Sterba <dsterba@suse.com>, Arnd Bergmann <arnd@arndb.de>,
	Song Liu <song@kernel.org>,
	Yu Kuai
	<yukuai@alb-78bjiv52429oh8qptp.cn-shenzhen.alb.aliyuncs.com>,
	Li Nan <linan122@huawei.com>,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, loongarch@lists.linux.dev,
	linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org,
	linux-s390@vger.kernel.org, linux-crypto@vger.kernel.org,
	linux-btrfs@vger.kernel.org, linux-arch@vger.kernel.org,
	linux-raid@vger.kernel.org
Subject: Re: cleanup the RAID6 P/Q library v3
Date: Mon, 29 Jun 2026 14:21:52 +0200	[thread overview]
Message-ID: <20260629122152.GA21344@lst.de> (raw)
In-Reply-To: <7d8efc7c-65e3-49f8-9381-910de7affef2@zytor.com>

On Fri, Jun 26, 2026 at 05:52:18PM -0700, H. Peter Anvin wrote:
> On 2026-05-19 01:24, Christoph Hellwig wrote:
> > 
> > raid6: rework registration of optimized algorithms
> > 
> >  - avx2 instead of avx512 is probably the right thing for no
> >    benchmarking, but if it was intentional (it wasn't), that should
> >    be document.  So I'll just switch back to the previous version to
> >    keep the state of the art
> 
> It is unlikely to be the right thing *going forward*, though.
> 
> The very unfortunate performance inversion is likely model-specific. It is one
> of those things where you largely would have to have a list of quirks :(

Note that the default is still to benchmark the implementations.
This is just about the case where the user explicitly disabled that
benchmark-based selection.


WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Christoph Hellwig <hch@lst.de>,
	Andrew Morton <akpm@linux-foundation.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>, Ard Biesheuvel <ardb@kernel.org>,
	Huacai Chen <chenhuacai@kernel.org>,
	WANG Xuerui <kernel@xen0n.name>,
	Madhavan Srinivasan <maddy@linux.ibm.com>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Nicholas Piggin <npiggin@gmail.com>,
	"Christophe Leroy (CS GROUP)" <chleroy@kernel.org>,
	Paul Walmsley <pjw@kernel.org>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Alexandre Ghiti <alex@ghiti.fr>,
	Heiko Carstens <hca@linux.ibm.com>,
	Vasily Gorbik <gor@linux.ibm.com>,
	Alexander Gordeev <agordeev@linux.ibm.com>,
	Christian Borntraeger <borntraeger@linux.ibm.com>,
	Sven Schnelle <svens@linux.ibm.com>,
	Thomas Gleixner <tglx@kernel.org>, Ingo Molnar <mingo@redhat.com>,
	Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	x86@kernel.org, Herbert Xu <herbert@gondor.apana.org.au>,
	Dan Williams <dan.j.williams@intel.com>, Chris Mason <clm@fb.com>,
	David Sterba <dsterba@suse.com>, Arnd Bergmann <arnd@arndb.de>,
	Song Liu <song@kernel.org>,
	Yu Kuai
	<yukuai@alb-78bjiv52429oh8qptp.cn-shenzhen.alb.aliyuncs.com>,
	Li Nan <linan122@huawei.com>,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, loongarch@lists.linux.dev,
	linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org,
	linux-s390@vger.kernel.org, linux-crypto@vger.kernel.org,
	linux-btrfs@vger.kernel.org, linux-arch@vger.kernel.org,
	linux-raid@vger.kernel.org
Subject: Re: cleanup the RAID6 P/Q library v3
Date: Mon, 29 Jun 2026 14:21:52 +0200	[thread overview]
Message-ID: <20260629122152.GA21344@lst.de> (raw)
In-Reply-To: <7d8efc7c-65e3-49f8-9381-910de7affef2@zytor.com>

On Fri, Jun 26, 2026 at 05:52:18PM -0700, H. Peter Anvin wrote:
> On 2026-05-19 01:24, Christoph Hellwig wrote:
> > 
> > raid6: rework registration of optimized algorithms
> > 
> >  - avx2 instead of avx512 is probably the right thing for no
> >    benchmarking, but if it was intentional (it wasn't), that should
> >    be document.  So I'll just switch back to the previous version to
> >    keep the state of the art
> 
> It is unlikely to be the right thing *going forward*, though.
> 
> The very unfortunate performance inversion is likely model-specific. It is one
> of those things where you largely would have to have a list of quirks :(

Note that the default is still to benchmark the implementations.
This is just about the case where the user explicitly disabled that
benchmark-based selection.


_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv

  reply	other threads:[~2026-06-29 12:22 UTC|newest]

Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-05-18  5:17 cleanup the RAID6 P/Q library v3 Christoph Hellwig
2026-05-18  5:17 ` Christoph Hellwig
2026-05-18  5:17 ` [PATCH 01/18] raid6: turn the userspace test harness into a kunit test Christoph Hellwig
2026-05-18  5:17   ` Christoph Hellwig
2026-06-26  8:20   ` patchwork-bot+linux-riscv
2026-06-26  8:20     ` patchwork-bot+linux-riscv
2026-05-18  5:17 ` [PATCH 02/18] raid6: remove __KERNEL__ ifdefs Christoph Hellwig
2026-05-18  5:17   ` Christoph Hellwig
2026-05-18  5:17 ` [PATCH 03/18] raid6: move to lib/raid/ Christoph Hellwig
2026-05-18  5:17   ` Christoph Hellwig
2026-05-18  5:17 ` [PATCH 04/18] raid6: remove unused defines in pq.h Christoph Hellwig
2026-05-18  5:17   ` Christoph Hellwig
2026-05-18  5:17 ` [PATCH 05/18] raid6: remove raid6_get_zero_page Christoph Hellwig
2026-05-18  5:17   ` Christoph Hellwig
2026-05-18  5:17 ` [PATCH 06/18] raid6: use named initializers for struct raid6_calls Christoph Hellwig
2026-05-18  5:17   ` Christoph Hellwig
2026-05-18  5:17 ` [PATCH 07/18] raid6: improve the public interface Christoph Hellwig
2026-05-18  5:17   ` Christoph Hellwig
2026-05-18  5:17 ` [PATCH 08/18] raid6: warn when using less than four devices Christoph Hellwig
2026-05-18  5:17   ` Christoph Hellwig
2026-06-27  1:14   ` H. Peter Anvin
2026-06-27  1:14     ` H. Peter Anvin
2026-05-18  5:17 ` [PATCH 09/18] raid6: hide internals Christoph Hellwig
2026-05-18  5:17   ` Christoph Hellwig
2026-05-18  5:17 ` [PATCH 10/18] raid6: rework registration of optimized algorithms Christoph Hellwig
2026-05-18  5:17   ` Christoph Hellwig
2026-05-18  5:17 ` [PATCH 11/18] raid6: use static_call for gen_syndrom and xor_syndrom Christoph Hellwig
2026-05-18  5:17   ` Christoph Hellwig
2026-05-18  5:17 ` [PATCH 12/18] raid6: use static_call for raid6_recov_2data and raid6_recov_datap Christoph Hellwig
2026-05-18  5:17   ` Christoph Hellwig
2026-05-18  5:17 ` [PATCH 13/18] raid6: update top of file comments Christoph Hellwig
2026-05-18  5:17   ` Christoph Hellwig
2026-05-18  5:17 ` [PATCH 14/18] raid6_kunit: use KUNIT_CASE_PARAM Christoph Hellwig
2026-05-18  5:17   ` Christoph Hellwig
2026-05-18  5:17 ` [PATCH 15/18] raid6_kunit: dynamically allocate data buffers using vmalloc Christoph Hellwig
2026-05-18  5:17   ` Christoph Hellwig
2026-05-18  5:17 ` [PATCH 16/18] raid6_kunit: cleanup dataptr handling Christoph Hellwig
2026-05-18  5:17   ` Christoph Hellwig
2026-05-18  5:18 ` [PATCH 17/18] raid6_kunit: randomize parameters and increase limits Christoph Hellwig
2026-05-18  5:18   ` Christoph Hellwig
2026-05-18  5:18 ` [PATCH 18/18] raid6_kunit: randomize buffer alignment Christoph Hellwig
2026-05-18  5:18   ` Christoph Hellwig
2026-05-18 21:12 ` cleanup the RAID6 P/Q library v3 Andrew Morton
2026-05-18 21:12   ` Andrew Morton
2026-05-19  8:24   ` Christoph Hellwig
2026-05-19  8:24     ` Christoph Hellwig
2026-06-27  0:52     ` H. Peter Anvin
2026-06-27  0:52       ` H. Peter Anvin
2026-06-29 12:21       ` Christoph Hellwig [this message]
2026-06-29 12:21         ` Christoph Hellwig
2026-06-29 12:34         ` H. Peter Anvin
2026-06-29 12:34           ` H. Peter Anvin
2026-06-29 12:48           ` Christoph Hellwig
2026-06-29 12:48             ` Christoph Hellwig
  -- strict thread matches above, loose matches on Subject: below --
2026-05-18  5:12 Christoph Hellwig
2026-05-18  5:12 ` Christoph Hellwig

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