From: Andi Kleen <ak@linux.intel.com>
To: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: Netdev <netdev@vger.kernel.org>,
kernel-hardening@lists.openwall.com,
LKML <linux-kernel@vger.kernel.org>,
linux-crypto@vger.kernel.org,
David Laight <David.Laight@aculab.com>, Ted Tso <tytso@mit.edu>,
Hannes Frederic Sowa <hannes@stressinduktion.org>,
edumazet@google.com,
Linus Torvalds <torvalds@linux-foundation.org>,
Eric Biggers <ebiggers3@gmail.com>,
Tom Herbert <tom@herbertland.com>,
davem@davemloft.net, luto@amacapital.net,
Jean-Philippe Aumasson <jeanphilippe.aumasson@gmail.com>
Subject: Re: [PATCH v7 6/6] siphash: implement HalfSipHash1-3 for hash tables
Date: Wed, 21 Dec 2016 16:46:35 -0800 [thread overview]
Message-ID: <20161222004635.GV8388@tassilo.jf.intel.com> (raw)
In-Reply-To: <20161221230216.25341-7-Jason@zx2c4.com>
> 64-bit x86_64:
> [ 0.509409] test_siphash: SipHash2-4 cycles: 4049181
> [ 0.510650] test_siphash: SipHash1-3 cycles: 2512884
> [ 0.512205] test_siphash: HalfSipHash1-3 cycles: 3429920
> [ 0.512904] test_siphash: JenkinsHash cycles: 978267
I'm not sure what these numbers mean. Surely a single siphash2-4
does not take 4+ million cycles?
If you run them in a loop please divide by the iterations.
But generally running small code in a loop is often an unrealistic
benchmark strategy because it hides cache misses, primes
predictors, changes frequencies and changes memory costs,
but also can overload pipelines and oversubscribe
resources.
[see also page 46+ in http://halobates.de/applicative-mental-models.pdf]
So the numbers you get there are at least somewhat
dubious. It would be good to have at least some test which
is not just a tiny micro benchmark to compare before making
conclusions.
-Andi
prev parent reply other threads:[~2016-12-22 0:46 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-15 20:29 [PATCH v5 0/4] The SipHash Patchset Jason A. Donenfeld
2016-12-15 20:30 ` [PATCH v5 1/4] siphash: add cryptographically secure PRF Jason A. Donenfeld
2016-12-15 22:42 ` George Spelvin
2016-12-16 2:14 ` kbuild test robot
2016-12-17 14:55 ` Jeffrey Walton
2016-12-19 17:08 ` Jason A. Donenfeld
2016-12-15 20:30 ` [PATCH v5 2/4] siphash: add Nu{32,64} helpers Jason A. Donenfeld
2016-12-16 10:39 ` David Laight
2016-12-16 15:44 ` George Spelvin
2016-12-15 20:30 ` [PATCH v5 3/4] secure_seq: use SipHash in place of MD5 Jason A. Donenfeld
2016-12-16 9:59 ` David Laight
2016-12-16 15:57 ` Jason A. Donenfeld
2016-12-15 20:30 ` [PATCH v5 4/4] random: " Jason A. Donenfeld
2016-12-16 3:03 ` [PATCH v6 0/5] The SipHash Patchset Jason A. Donenfeld
2016-12-16 3:03 ` [PATCH v6 1/5] siphash: add cryptographically secure PRF Jason A. Donenfeld
2016-12-16 3:03 ` [PATCH v6 2/5] secure_seq: use SipHash in place of MD5 Jason A. Donenfeld
2016-12-16 3:03 ` [PATCH v6 3/5] random: " Jason A. Donenfeld
2016-12-16 21:31 ` Andy Lutomirski
2016-12-16 3:03 ` [PATCH v6 4/5] md5: remove from lib and only live in crypto Jason A. Donenfeld
2016-12-16 3:03 ` [PATCH v6 5/5] syncookies: use SipHash in place of SHA1 Jason A. Donenfeld
2016-12-21 23:02 ` [PATCH v7 0/6] The SipHash Patchset Jason A. Donenfeld
2016-12-21 23:02 ` [PATCH v7 1/6] siphash: add cryptographically secure PRF Jason A. Donenfeld
2016-12-22 1:40 ` Stephen Hemminger
2016-12-21 23:02 ` [PATCH v7 2/6] secure_seq: use SipHash in place of MD5 Jason A. Donenfeld
2016-12-21 23:02 ` [PATCH v7 3/6] random: " Jason A. Donenfeld
2016-12-21 23:13 ` Jason A. Donenfeld
2016-12-21 23:42 ` Andy Lutomirski
2016-12-22 2:07 ` Hannes Frederic Sowa
2016-12-22 2:09 ` Andy Lutomirski
2016-12-22 2:49 ` Jason A. Donenfeld
2016-12-22 3:12 ` Jason A. Donenfeld
2016-12-22 5:41 ` [kernel-hardening] " Theodore Ts'o
2016-12-22 6:03 ` Jason A. Donenfeld
2016-12-22 15:58 ` Theodore Ts'o
2016-12-22 16:16 ` Jason A. Donenfeld
2016-12-22 16:30 ` Theodore Ts'o
2016-12-22 16:36 ` Jason A. Donenfeld
2016-12-22 12:47 ` Hannes Frederic Sowa
2016-12-22 13:10 ` Jason A. Donenfeld
2016-12-22 15:05 ` Hannes Frederic Sowa
2016-12-22 15:12 ` Jason A. Donenfeld
2016-12-22 15:29 ` Jason A. Donenfeld
2016-12-22 15:33 ` Hannes Frederic Sowa
2016-12-22 15:41 ` Jason A. Donenfeld
2016-12-22 15:51 ` Hannes Frederic Sowa
2016-12-22 15:53 ` Jason A. Donenfeld
2016-12-22 15:54 ` Theodore Ts'o
2016-12-22 18:08 ` Hannes Frederic Sowa
2016-12-22 18:13 ` Jason A. Donenfeld
2016-12-22 19:50 ` Theodore Ts'o
2016-12-22 2:31 ` Jason A. Donenfeld
2016-12-21 23:02 ` [PATCH v7 4/6] md5: remove from lib and only live in crypto Jason A. Donenfeld
2016-12-21 23:02 ` [PATCH v7 5/6] syncookies: use SipHash in place of SHA1 Jason A. Donenfeld
2016-12-21 23:02 ` [PATCH v7 6/6] siphash: implement HalfSipHash1-3 for hash tables Jason A. Donenfeld
2016-12-22 0:46 ` Andi Kleen [this message]
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