From: Matt Mackall <mpm@selenic.com>
To: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Ingo Oeser <ioe-lkml@rameria.de>,
lode leroy <lode_leroy@hotmail.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] memchr (trivial) optimization
Date: Thu, 23 Aug 2007 21:19:53 -0500 [thread overview]
Message-ID: <20070824021953.GG21720@waste.org> (raw)
In-Reply-To: <46CE2E61.9010408@goop.org>
On Thu, Aug 23, 2007 at 06:03:29PM -0700, Jeremy Fitzhardinge wrote:
> Matt Mackall wrote:
> > 6e: 38 08 cmp %cl,(%eax)
> > 70: 74 07 je 79 <memchr3+0x1b>
> > 72: 40 inc %eax
> >
> It's a bit gross that the compiler is using inc here rather than lea or
> add, but still...
>
> Er, something's spending 30% of its time in memchr? This is not the
> code to fix.
Indeed. I'm just pointing out the general optimization of walking
one counter instead of two.
Hmm, perhaps the culprit is validate_nla?
--
Mathematics is the supreme nostalgia of our time.
next prev parent reply other threads:[~2007-08-24 2:18 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-08-22 9:34 [PATCH] memchr (trivial) optimization lode leroy
2007-08-22 10:56 ` Andi Kleen
2007-08-23 0:13 ` Ingo Oeser
2007-08-24 0:13 ` Matt Mackall
2007-08-24 1:03 ` Jeremy Fitzhardinge
2007-08-24 2:19 ` Matt Mackall [this message]
2007-08-24 12:54 ` Jan Engelhardt
2007-08-24 15:57 ` Matt Mackall
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