linux-kernel - Re: [PATCH] memchr (trivial) optimization

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 23 Aug 2007 21:19:53 -0500
From:	Matt Mackall <mpm@...enic.com>
To:	Jeremy Fitzhardinge <jeremy@...p.org>
Cc:	Ingo Oeser <ioe-lkml@...eria.de>,
	lode leroy <lode_leroy@...mail.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] memchr (trivial) optimization

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.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/