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From: Bernd Petrovitsch <bernd@petrovitsch.priv.at>
To: pavel@pavlinux.ru
Cc: LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] Repalce strncmp by memcmp
Date: Tue, 30 Nov 2010 11:34:20 +0100	[thread overview]
Message-ID: <1291113260.16068.13.camel@thorin> (raw)
In-Reply-To: <4CF30B46.4000203@pavlinux.ru>

On Mon, 2010-11-29 at 05:09 +0300, Pavel Vasilyev wrote: 
> This patch replace all strncmp(a, b, c) by  memcmp(a, b, c).
> 
> I test on x86_64 (AMD Opteron 285).
> 
> #include <string.h>
> char *A = "0000";
> void test_memcmp(void) {
>         memcmp(A, "TEST", 4);
> }
> void test_strn(void) {
>         strncmp(A, "TEST", 4);
> }
[...]

You use constant parameters with user-space functions defined by the
C-standard on one architecture (and CPU?) - and even worse the width is
4 so - for the memcmp() case - it boilsdown to a comparison of unsigned
ints.
So that example is (also) completely worthless.

Bernd
-- 
Bernd Petrovitsch                  Email : bernd@petrovitsch.priv.at
                     LUGA : http://www.luga.at


      parent reply	other threads:[~2010-11-30 10:34 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-11-29  2:09 [PATCH] Repalce strncmp by memcmp Pavel Vasilyev
2010-11-29  2:21 ` microcai
2010-11-29  2:29 ` Ming Lei
2010-11-29  3:11   ` Pavel Vasilyev
2010-11-29  4:13     ` Dmitry Torokhov
2010-11-29  5:26       ` YOSHIFUJI Hideaki
2010-11-29 12:41         ` Pavel Vasilyev
2010-11-29  3:10 ` Américo Wang
2010-11-29 10:18 ` Andi Kleen
2010-11-29 14:58 ` Steven Rostedt
2010-11-29 19:41   ` Pavel Vasilyev
2010-11-29 22:18     ` Steven Rostedt
2010-11-29 22:26       ` Steven Rostedt
2010-11-29 22:49         ` Pavel Vasilyev
2010-11-30  9:24           ` Américo Wang
2010-11-29 22:51         ` Ryan Mallon
2010-11-30 10:27           ` Bernd Petrovitsch
2010-11-29 23:32 ` Arnaud Lacombe
2010-11-30 10:34 ` Bernd Petrovitsch [this message]

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