From: "H. Peter Anvin" <hpa@zytor.com>
To: Neil Horman <nhorman@tuxdriver.com>, linux-kernel@vger.kernel.org
Cc: sebastien.dugue@bull.net, Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
x86@kernel.org
Subject: Re: [PATCH] x86: Run checksumming in parallel accross multiple alu's
Date: Sat, 12 Oct 2013 15:29:24 -0700 [thread overview]
Message-ID: <5259CD44.2000200@zytor.com> (raw)
In-Reply-To: <1381510298-20572-1-git-send-email-nhorman@tuxdriver.com>
On 10/11/2013 09:51 AM, Neil Horman wrote:
> Sébastien Dugué reported to me that devices implementing ipoib (which don't have
> checksum offload hardware were spending a significant amount of time computing
> checksums. We found that by splitting the checksum computation into two
> separate streams, each skipping successive elements of the buffer being summed,
> we could parallelize the checksum operation accros multiple alus. Since neither
> chain is dependent on the result of the other, we get a speedup in execution (on
> hardware that has multiple alu's available, which is almost ubiquitous on x86),
> and only a negligible decrease on hardware that has only a single alu (an extra
> addition is introduced). Since addition in commutative, the result is the same,
> only faster
On hardware that implement ADCX/ADOX then you should also be able to
have additional streams interleaved since those instructions allow for
dual carry chains.
-hpa
next prev parent reply other threads:[~2013-10-12 22:30 UTC|newest]
Thread overview: 132+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-11 16:51 [PATCH] x86: Run checksumming in parallel accross multiple alu's Neil Horman
2013-10-12 17:21 ` Ingo Molnar
2013-10-13 12:53 ` Neil Horman
2013-10-14 20:28 ` Neil Horman
2013-10-14 21:19 ` Eric Dumazet
2013-10-14 22:18 ` Eric Dumazet
2013-10-14 22:37 ` Joe Perches
2013-10-14 22:44 ` Eric Dumazet
2013-10-14 22:49 ` Joe Perches
2013-10-15 7:41 ` Ingo Molnar
2013-10-15 10:51 ` Borislav Petkov
2013-10-15 12:04 ` Ingo Molnar
2013-10-15 16:21 ` Joe Perches
2013-10-16 0:34 ` Eric Dumazet
2013-10-16 6:25 ` Ingo Molnar
2013-10-16 16:55 ` Joe Perches
2013-10-17 0:34 ` Neil Horman
2013-10-17 1:42 ` Eric Dumazet
2013-10-18 16:50 ` Neil Horman
2013-10-18 17:20 ` Eric Dumazet
2013-10-18 20:11 ` Neil Horman
2013-10-18 21:15 ` Eric Dumazet
2013-10-20 21:29 ` Neil Horman
2013-10-21 17:31 ` Eric Dumazet
2013-10-21 17:46 ` Neil Horman
2013-10-21 19:21 ` Neil Horman
2013-10-21 19:44 ` Eric Dumazet
2013-10-21 20:19 ` Neil Horman
2013-10-26 12:01 ` Ingo Molnar
2013-10-26 13:58 ` Neil Horman
2013-10-27 7:26 ` Ingo Molnar
2013-10-27 17:05 ` Neil Horman
2013-10-17 8:41 ` Ingo Molnar
2013-10-17 18:19 ` H. Peter Anvin
2013-10-17 18:48 ` Eric Dumazet
2013-10-18 6:43 ` Ingo Molnar
2013-10-28 16:01 ` Neil Horman
2013-10-28 16:20 ` Ingo Molnar
2013-10-28 17:49 ` Neil Horman
2013-10-28 16:24 ` Ingo Molnar
2013-10-28 16:49 ` David Ahern
2013-10-28 17:46 ` Neil Horman
2013-10-28 18:29 ` Neil Horman
2013-10-29 8:25 ` Ingo Molnar
2013-10-29 11:20 ` Neil Horman
2013-10-29 11:30 ` Ingo Molnar
2013-10-29 11:49 ` Neil Horman
2013-10-29 12:52 ` Ingo Molnar
2013-10-29 13:07 ` Neil Horman
2013-10-29 13:11 ` Ingo Molnar
2013-10-29 13:20 ` Neil Horman
2013-10-29 14:17 ` Neil Horman
2013-10-29 14:27 ` Ingo Molnar
2013-10-29 20:26 ` Neil Horman
2013-10-31 10:22 ` Ingo Molnar
2013-10-31 14:33 ` Neil Horman
2013-11-01 9:13 ` Ingo Molnar
2013-11-01 14:06 ` Neil Horman
2013-10-29 14:12 ` David Ahern
2013-10-15 7:32 ` Ingo Molnar
2013-10-15 13:14 ` Neil Horman
2013-10-12 22:29 ` H. Peter Anvin [this message]
2013-10-13 12:53 ` Neil Horman
2013-10-18 16:42 ` Neil Horman
2013-10-18 17:09 ` H. Peter Anvin
2013-10-25 13:06 ` Neil Horman
2013-10-14 4:38 ` Andi Kleen
2013-10-14 7:49 ` Ingo Molnar
2013-10-14 21:07 ` Eric Dumazet
2013-10-15 13:17 ` Neil Horman
2013-10-14 20:25 ` Neil Horman
2013-10-15 7:12 ` Sébastien Dugué
2013-10-15 13:33 ` Andi Kleen
2013-10-15 13:56 ` Sébastien Dugué
2013-10-15 14:06 ` Eric Dumazet
2013-10-15 14:15 ` Sébastien Dugué
2013-10-15 14:26 ` Eric Dumazet
2013-10-15 14:52 ` Eric Dumazet
2013-10-15 16:02 ` Andi Kleen
2013-10-16 0:28 ` Eric Dumazet
2013-11-06 15:23 ` x86: Enhance perf checksum profiling and x86 implementation Neil Horman
2013-11-06 15:23 ` [PATCH v2 1/2] perf: Add csum benchmark tests to perf Neil Horman
2013-11-06 15:23 ` [PATCH v2 2/2] x86: add prefetching to do_csum Neil Horman
2013-11-06 15:34 ` Dave Jones
2013-11-06 15:54 ` Neil Horman
2013-11-06 17:19 ` Joe Perches
2013-11-06 18:11 ` Neil Horman
2013-11-06 20:02 ` Neil Horman
2013-11-06 20:07 ` Joe Perches
2013-11-08 16:25 ` Neil Horman
2013-11-08 16:51 ` Joe Perches
2013-11-08 19:07 ` Neil Horman
2013-11-08 19:17 ` Joe Perches
2013-11-08 20:08 ` Neil Horman
2013-11-08 19:17 ` H. Peter Anvin
2013-11-08 19:01 ` Neil Horman
2013-11-08 19:33 ` Joe Perches
2013-11-08 20:14 ` Neil Horman
2013-11-08 20:29 ` Joe Perches
2013-11-11 19:40 ` Neil Horman
2013-11-11 21:18 ` Ingo Molnar
2013-11-06 18:23 ` Eric Dumazet
2013-11-06 18:59 ` Neil Horman
2013-11-06 20:19 ` Andi Kleen
2013-11-07 21:23 ` Neil Horman
-- strict thread matches above, loose matches on Subject: below --
2013-10-18 15:46 [PATCH] x86: Run checksumming in parallel accross multiple alu's Doug Ledford
2013-10-18 17:42 Doug Ledford
2013-10-19 8:23 ` Ingo Molnar
2013-10-21 17:54 ` Doug Ledford
2013-10-26 11:55 ` Ingo Molnar
2013-10-28 17:02 ` Doug Ledford
2013-10-29 8:38 ` Ingo Molnar
2013-10-30 5:25 Doug Ledford
2013-10-30 10:27 ` David Laight
2013-10-30 11:02 ` Neil Horman
2013-10-30 12:18 ` David Laight
2013-10-30 13:22 ` Doug Ledford
2013-10-30 13:35 ` Doug Ledford
2013-10-30 14:04 ` David Laight
2013-10-30 14:52 ` Neil Horman
2013-10-31 18:30 ` Neil Horman
2013-11-01 9:21 ` Ingo Molnar
2013-11-01 15:42 ` Ben Hutchings
2013-11-01 16:08 ` Neil Horman
2013-11-01 16:16 ` Ben Hutchings
2013-11-01 16:18 ` David Laight
2013-11-01 17:37 ` Neil Horman
2013-11-01 19:45 ` Joe Perches
2013-11-01 19:58 ` Neil Horman
2013-11-01 20:26 ` Joe Perches
2013-11-02 2:07 ` Neil Horman
2013-11-04 9:47 ` David Laight
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