From: Eric Biggers <ebiggers@kernel.org>
To: linux-kernel@vger.kernel.org
Cc: Bill Wendling <morbo@google.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "H . Peter Anvin" <hpa@zytor.com>,
Ard Biesheuvel <ardb@kernel.org>,
Nathan Chancellor <nathan@kernel.org>,
Nick Desaulniers <nick.desaulniers+lkml@gmail.com>,
Justin Stitt <justinstitt@google.com>,
David Laight <david.laight.linux@gmail.com>,
linux-crypto@vger.kernel.org, llvm@lists.linux.dev
Subject: Re: [PATCH] x86/crc32: optimize tail handling for crc32c short inputs
Date: Thu, 6 Mar 2025 09:21:07 -0800 [thread overview]
Message-ID: <20250306172107.GA1796@sol.localdomain> (raw)
In-Reply-To: <20250304213216.108925-1-ebiggers@kernel.org>
On Tue, Mar 04, 2025 at 01:32:16PM -0800, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
>
> For handling the 0 <= len < sizeof(unsigned long) bytes left at the end,
> do a 4-2-1 step-down instead of a byte-at-a-time loop. This allows
> taking advantage of wider CRC instructions. Note that crc32c-3way.S
> already uses this same optimization too.
>
> crc_kunit shows an improvement of about 25% for len=127.
>
> Suggested-by: H. Peter Anvin <hpa@zytor.com>
> Signed-off-by: Eric Biggers <ebiggers@google.com>
> ---
>
> This applies to
> https://web.git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux.git/log/?h=crc-next
Applied to
https://web.git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux.git/log/?h=crc-next
- Eric
prev parent reply other threads:[~2025-03-06 17:21 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-03-04 21:32 [PATCH] x86/crc32: optimize tail handling for crc32c short inputs Eric Biggers
2025-03-05 10:10 ` Uros Bizjak
2025-03-05 14:26 ` David Laight
2025-03-05 19:16 ` Eric Biggers
2025-03-05 22:07 ` David Laight
2025-03-06 2:56 ` Eric Biggers
2025-03-06 5:17 ` David Laight
2025-03-06 17:21 ` Eric Biggers [this message]
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