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From: Dave Jones <davej@redhat.com>
To: Jan Engelhardt <jengelh@linux01.gwdg.de>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] no need to check for NULL before calling kfree() -fs/ext2/
Date: Sun, 27 Mar 2005 12:40:26 -0500	[thread overview]
Message-ID: <20050327174026.GA708@redhat.com> (raw)
In-Reply-To: <Pine.LNX.4.61.0503271708350.20909@yvahk01.tjqt.qr>

On Sun, Mar 27, 2005 at 05:12:58PM +0200, Jan Engelhardt wrote:

 > Well, kfree inlined was already mentioned but forgotten again.
 > What if this was used:
 > 
 > inline static void kfree_WRAP(void *addr) {
 >     if(likely(addr != NULL)) {
 >         kfree_real(addr);
 >     }
 >     return;
 > }
 > 
 > And remove the NULL-test in kfree_real()? Then we would have:

Am I the only person who is completely fascinated by the
effort being spent here micro-optimising something thats
almost never in a path that needs optimising ?
I'd be amazed if any of this masturbation showed the tiniest
blip on a real workload, or even on a benchmark other than
one crafted specifically to test kfree in a loop.

That each occurance of this 'optimisation' also saves a handful
of bytes in generated code is it's only real benefit afaics.
Even then, if a functions cache performance is better off because
we trimmed a few bytes from the tail of a function, I'd be
completely amazed.

I guess April 1st came early this year.

		Dave


  reply	other threads:[~2005-03-27 17:40 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-03-25 22:08 [PATCH] no need to check for NULL before calling kfree() - fs/ext2/ Jesper Juhl
2005-03-25 22:29 ` linux-os
2005-03-25 22:44   ` Jesper Juhl
2005-03-26  7:50   ` Pekka Enberg
2005-03-26  8:32   ` Arjan van de Ven
2005-03-26 23:21     ` [PATCH] no need to check for NULL before calling kfree() -fs/ext2/ linux-os
2005-03-26 23:34       ` Marcin Dalecki
2005-03-27  2:00         ` Horst von Brand
2005-03-27  3:18           ` Marcin Dalecki
2005-03-27 22:12         ` linux-os
2005-03-26 23:54       ` Jesper Juhl
2005-03-27  0:05         ` Lee Revell
2005-03-27 10:55           ` Jesper Juhl
2005-03-27 14:56             ` Paul Jackson
2005-03-27 15:12               ` Jan Engelhardt
2005-03-27 17:40                 ` Dave Jones [this message]
2005-03-27 18:17                   ` Jan Engelhardt
2005-03-27 19:25                   ` Pekka Enberg
2005-03-27 22:56                   ` Jesper Juhl
2005-03-28  4:53                     ` Paul Jackson
2005-03-30 18:57                       ` Jesper Juhl
2005-03-28  1:20                   ` Horst von Brand
2005-03-28  4:10                   ` Paul Jackson
2005-03-28 12:58                   ` Geert Uytterhoeven
2005-03-29  2:52                   ` Lee Revell
2005-03-29  6:30                     ` Pekka Enberg
2005-03-29  7:06                       ` Jan Engelhardt
2005-03-29  7:24                         ` Pekka J Enberg
2005-03-30  2:44                           ` Paul Jackson
2005-03-30  6:13                             ` Pekka J Enberg
2005-03-30  6:16                               ` Paul Jackson
2005-03-30  7:15                               ` P Lavin
2005-03-30 14:20                                 ` Jesper Juhl
2005-03-30 19:10                             ` Jesper Juhl
2005-04-09  2:21                               ` Jesper Juhl
2005-03-28  4:07                 ` [PATCH] " Paul Jackson
2005-03-27  8:45       ` Arjan van de Ven
2005-03-27 12:51         ` Denis Vlasenko
2005-03-27 14:28           ` Arjan van de Ven
2005-03-27 23:13         ` [PATCH] no need to check for NULL before calling kfree()-fs/ext2/ linux-os

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