From: David Laight <David.Laight@ACULAB.COM>
To: 'Noah Goldstein' <goldstein.w.n@gmail.com>,
"x86@kernel.org" <x86@kernel.org>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"edumazet@google.com" <edumazet@google.com>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"mingo@redhat.com" <mingo@redhat.com>,
"torvalds@linux-foundation.org" <torvalds@linux-foundation.org>,
"bp@alien8.de" <bp@alien8.de>,
"dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
"hpa@zytor.com" <hpa@zytor.com>
Subject: RE: x86/csum: Remove unnecessary odd handling
Date: Wed, 6 Sep 2023 14:38:49 +0000 [thread overview]
Message-ID: <d4c6e6274bd14391a1e59f84f9ebce7a@AcuMS.aculab.com> (raw)
In-Reply-To: <20230901222100.1027371-1-goldstein.w.n@gmail.com>
From: Noah Goldstein
> Sent: 01 September 2023 23:21
...
> + return add32_with_carry(temp64 >> 32, temp64 & 0xffffffff);
The generic C alternative:
return (temp64 + ror64(temp64, 32)) >> 32;
is the same number of instructions but might get
better scheduling.
The C version of csum_fold() from arc/include/asm/checksum.h
is also better than the x86 asm version.
(And also pretty much all the other architecture dependant
copies.)
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2023-09-06 14:38 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20230628020657.957880-1-goldstein.w.n@gmail.com>
2023-06-28 9:12 ` Borislav Petkov
2023-06-28 15:32 ` Noah Goldstein
2023-06-28 17:44 ` Linus Torvalds
2023-06-28 18:34 ` Noah Goldstein
2023-06-28 20:02 ` Linus Torvalds
2023-06-29 14:04 ` David Laight
2023-06-29 14:27 ` David Laight
2023-09-01 22:21 ` Noah Goldstein
2023-09-06 13:49 ` David Laight
2023-09-06 14:38 ` David Laight [this message]
2023-09-20 19:20 ` Noah Goldstein
2023-09-20 19:23 ` Noah Goldstein
2023-09-23 3:24 ` kernel test robot
2023-09-23 14:05 ` Noah Goldstein
2023-09-23 21:13 ` David Laight
2023-09-24 14:35 ` Noah Goldstein
2023-12-23 22:18 ` Noah Goldstein
2024-01-04 23:28 ` Noah Goldstein
2024-01-04 23:34 ` Dave Hansen
2024-01-04 23:36 ` Linus Torvalds
2024-01-05 0:33 ` Linus Torvalds
2024-01-05 10:41 ` David Laight
2024-01-05 16:12 ` David Laight
2024-01-05 18:05 ` Linus Torvalds
2024-01-05 23:52 ` David Laight
2024-01-06 0:18 ` Linus Torvalds
2024-01-06 10:26 ` Eric Dumazet
2024-01-06 19:32 ` Linus Torvalds
2024-01-07 12:11 ` David Laight
2024-01-06 22:08 ` David Laight
2024-01-07 1:09 ` H. Peter Anvin
2024-01-07 11:44 ` David Laight
2023-09-24 14:35 ` Noah Goldstein
2025-10-24 22:12 Ywe Cærlyn
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