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From: "George Spelvin" <linux@sciencehorizons.net>
To: Jason@zx2c4.com, linux@sciencehorizons.net
Cc: ak@linux.intel.com, davem@davemloft.net, David.Laight@aculab.com,
	djb@cr.yp.to, ebiggers3@gmail.com, eric.dumazet@gmail.com,
	hannes@stressinduktion.org, jeanphilippe.aumasson@gmail.com,
	kernel-hardening@lists.openwall.com,
	linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org,
	luto@amacapital.net, netdev@vger.kernel.org, tom@herbertland.com,
	torvalds@linux-foundation.org, tytso@mit.edu,
	vegard.nossum@gmail.com
Subject: Re: HalfSipHash Acceptable Usage
Date: 21 Dec 2016 10:55:40 -0500	[thread overview]
Message-ID: <20161221155540.29529.qmail@ns.sciencehorizons.net> (raw)
In-Reply-To: <CAHmME9oJDOLpPKRpX=N+DY9BuzTueWjTaWzeVtdVMBG7mcrqKA@mail.gmail.com>

Actually, DJB just made a very relevant suggestion.

As I've mentioned, the 32-bit performance problems are an x86-specific
problem.  ARM does very well, and other processors aren't bad at all.

SipHash fits very nicely (and runs very fast) in the MMX registers.

They're 64 bits, and there are 8 of them, so the integer registers can
be reserved for pointers and loop counters and all that.  And there's
reference code available.

How much does kernel_fpu_begin()/kernel_fpu_end() cost?

Although there are a lot of pre-MMX x86es in embedded control applications,
I don't think anyone is worried about their networking performance.
(Specifically, all of this affects only connection setup, not throughput 
on established connections.)

  reply	other threads:[~2016-12-21 15:55 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-12-19 17:32 Jason A. Donenfeld
     [not found] ` <CAGiyFdduUNSGq24zfsk0ZU=hnOCmewAw8vw6XvDoS-3f+3UPKQ@mail.gmail.com>
2016-12-19 21:00   ` Jason A. Donenfeld
2016-12-20 21:36 ` Theodore Ts'o
2016-12-20 23:07   ` George Spelvin
2016-12-20 23:55   ` Eric Dumazet
2016-12-21  3:28     ` George Spelvin
2016-12-21  5:29       ` Eric Dumazet
2016-12-21  6:34         ` George Spelvin
2016-12-21 14:24           ` Jason A. Donenfeld
2016-12-21 15:55             ` George Spelvin [this message]
2016-12-21 16:37               ` Jason A. Donenfeld
2016-12-21 16:41               ` [kernel-hardening] " Rik van Riel
2016-12-21 17:25               ` Linus Torvalds
2016-12-21 18:07                 ` George Spelvin
2016-12-22  1:54                 ` Andy Lutomirski
2016-12-21 14:42         ` Jason A. Donenfeld
2016-12-21 15:56           ` Eric Dumazet
2016-12-21 16:33             ` Jason A. Donenfeld
2016-12-21 16:39             ` [kernel-hardening] " Rik van Riel
2016-12-21 17:08               ` Eric Dumazet
2016-12-21 18:37             ` George Spelvin
2016-12-21 18:40               ` Jason A. Donenfeld
2016-12-21 22:27               ` Theodore Ts'o
2016-12-22  0:18                 ` George Spelvin
2016-12-22  1:13                 ` George Spelvin

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