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Groups > linux.kernel > #1545585

Re: HalfSipHash Acceptable Usage

From Eric Dumazet <eric.dumazet@gmail.com>
Newsgroups linux.kernel
Subject Re: HalfSipHash Acceptable Usage
Date 2016-12-21 06:30 +0100
Message-ID <sQHDs-7EN-7@gated-at.bofh.it> (permalink)
References <sQFLj-6pl-5@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Tue, 2016-12-20 at 22:28 -0500, George Spelvin wrote:
> > I do not see why SipHash, if faster than MD5 and more secure, would be a
> > problem.
> 
> Because on 32-bit x86, it's slower.
> 
> Cycles per byte on 1024 bytes of data:
> 			Pentium	Core 2	Ivy
> 			4	Duo	Bridge
> SipHash-2-4		38.9	 8.3	 5.8
> HalfSipHash-2-4		12.7	 4.5	 3.2
> MD5			 8.3	 5.7	 4.7

So definitely not faster.

38 cycles per byte is a problem, considering IPV6 is ramping up.

But TCP session establishment on P4 is probably not a big deal.
Nobody would expect a P4 to handle gazillions of TCP flows (using a
32bit kernel)

What about SHA performance (syncookies) on P4 ?

Synfloods are probably the only case we might take care of for 2000-era
cpus.

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Thread

HalfSipHash Acceptable Usage "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-19 18:40 +0100
  Re: HalfSipHash Acceptable Usage "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-19 22:10 +0100
  Re: HalfSipHash Acceptable Usage Theodore Ts'o <tytso@mit.edu> - 2016-12-20 22:40 +0100
    Re: HalfSipHash Acceptable Usage "George Spelvin" <linux@sciencehorizons.net> - 2016-12-21 00:10 +0100
    Re: HalfSipHash Acceptable Usage Eric Dumazet <eric.dumazet@gmail.com> - 2016-12-21 01:00 +0100
      Re: HalfSipHash Acceptable Usage "George Spelvin" <linux@sciencehorizons.net> - 2016-12-21 04:30 +0100
        Re: HalfSipHash Acceptable Usage Eric Dumazet <eric.dumazet@gmail.com> - 2016-12-21 06:30 +0100
          Re: HalfSipHash Acceptable Usage "George Spelvin" <linux@sciencehorizons.net> - 2016-12-21 07:40 +0100
            Re: HalfSipHash Acceptable Usage "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-21 15:30 +0100
              Re: HalfSipHash Acceptable Usage "George Spelvin" <linux@sciencehorizons.net> - 2016-12-21 17:00 +0100
                Re: HalfSipHash Acceptable Usage "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-21 17:40 +0100
                Re: [kernel-hardening] Re: HalfSipHash Acceptable Usage Rik van Riel <riel@redhat.com> - 2016-12-21 17:50 +0100
                Re: HalfSipHash Acceptable Usage Linus Torvalds <torvalds@linux-foundation.org> - 2016-12-21 18:30 +0100
                Re: HalfSipHash Acceptable Usage "George Spelvin" <linux@sciencehorizons.net> - 2016-12-21 19:10 +0100
                Re: HalfSipHash Acceptable Usage Andy Lutomirski <luto@amacapital.net> - 2016-12-22 03:10 +0100
          Re: HalfSipHash Acceptable Usage "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-21 15:50 +0100
            Re: HalfSipHash Acceptable Usage Eric Dumazet <eric.dumazet@gmail.com> - 2016-12-21 17:00 +0100
              Re: HalfSipHash Acceptable Usage "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-21 17:40 +0100
              Re: [kernel-hardening] Re: HalfSipHash Acceptable Usage Rik van Riel <riel@redhat.com> - 2016-12-21 17:40 +0100
                Re: [kernel-hardening] Re: HalfSipHash Acceptable Usage Eric Dumazet <eric.dumazet@gmail.com> - 2016-12-21 18:10 +0100
              Re: HalfSipHash Acceptable Usage "George Spelvin" <linux@sciencehorizons.net> - 2016-12-21 19:40 +0100
                Re: HalfSipHash Acceptable Usage "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-21 19:50 +0100
                Re: HalfSipHash Acceptable Usage Theodore Ts'o <tytso@mit.edu> - 2016-12-21 23:30 +0100
                Re: HalfSipHash Acceptable Usage "George Spelvin" <linux@sciencehorizons.net> - 2016-12-22 01:20 +0100
                Re: HalfSipHash Acceptable Usage "George Spelvin" <linux@sciencehorizons.net> - 2016-12-22 02:20 +0100

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