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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Giuseppe Scrivano <gscrivano@gnu.org>
Cc: Bug-coreutils@gnu.org, "Pádraig Brady" <P@draigBrady.com>,
	"Git Mailing List" <git@vger.kernel.org>
Subject: Re: Linus' sha1 is much faster!
Date: Sun, 16 Aug 2009 13:10:20 -0700 (PDT)	[thread overview]
Message-ID: <alpine.LFD.2.01.0908161306340.3162@localhost.localdomain> (raw)
In-Reply-To: <87eirbef3c.fsf@master.homenet>



On Sun, 16 Aug 2009, Giuseppe Scrivano wrote:
> 
> My GCC version is "gcc (Debian 4.3.3-14) 4.3.3" and the CPU is: Intel(R)
> Pentium(R) D CPU 3.20GHz.

Netburst is very sensitive to random spill effects, and you can basically 
tune things by just code shuffling that just has random effects on the 
generated asm code.

> I also spent some time trying to improve the gnulib SHA1 implementation
> and it seems a lookup table can improve things a bit.

I pretty much can guarantee you that it improves things only because it 
makes gcc generate crap code, which then hides some of the P4 issues.

I'd also suggest you try gcc-4.4, since that apparently fixes some of the 
oddest spill issues.

			Linus

  reply	other threads:[~2009-08-16 20:10 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-08-14 23:25 Linus' sha1 is much faster! Pádraig Brady
2009-08-15 20:02 ` Bryan Donlan
2009-08-15 20:12   ` John Tapsell
2009-08-15 20:23     ` Linus Torvalds
2009-08-15 20:54       ` Linus Torvalds
2009-08-17  1:55         ` Nicolas Pitre
2009-08-26 11:39           ` Pádraig Brady
2017-04-20 21:35             ` galt
2017-04-20 21:38             ` galt
2009-08-17  8:22         ` Andreas Ericsson
2009-08-16  0:06     ` Theodore Tso
2009-08-16 19:25 ` Giuseppe Scrivano
2009-08-16 20:10   ` Linus Torvalds [this message]
2009-08-16 22:15     ` Giuseppe Scrivano
2009-08-16 22:47       ` Linus Torvalds
2009-08-17  1:53   ` Pádraig Brady
2009-08-17 10:51     ` Giuseppe Scrivano
2009-08-17 15:44       ` Steven Noonan
2009-08-17 16:22         ` Linus Torvalds
2009-08-17 21:43           ` Steven Noonan
2009-08-17 17:32         ` Giuseppe Scrivano
  -- strict thread matches above, loose matches on Subject: below --
2009-08-17  7:23 George Spelvin
2009-08-17 14:20 ` Nicolas Pitre
2009-08-17 17:06 ` Nicolas Pitre
2009-08-17 17:20   ` Paolo Bonzini
2009-08-17 18:54   ` George Spelvin
2009-08-17 19:34     ` Nicolas Pitre
2009-08-17 23:12       ` George Spelvin

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