lkml.org 
[lkml]   [2006]   [Apr]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] likely cleanup: remove unlikely for kfree(NULL)
From
Date
On Thu, 2006-04-27 at 09:28 +0300, Pekka J Enberg wrote:
> On Thu, 27 Apr 2006, Nick Piggin wrote:
> > Not to dispute your conclusions or method, but I think doing a
> > defconfig or your personal config might be more representative
> > of % size increase of text that will actually be executed. And
> > that is the expensive type of text.
>
> True but I was under the impression that Arjan thought we'd get text
> savings with GCC 4.1 by making kfree() inline.

not savings in text size, I'll settle for the same size.
What we gain is less branches in the hotpath... eg a kfree that gets
optimized now has one less branch. Note that the branch predictor isn't
going to help you for these 100% cases, since the same branch "slot" is
shared between all callers; with this inline the branch predictor at
least gets to keep stats for each of the callers individually.
That is where the gain is....
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2006-04-27 08:53    [from the cache]
©2003-2011 Jasper Spaans. Advertise on this site