From: Marcin Slusarz <marcin.slusarz@gmail.com>
Date: Sun, 26 Jun 2011 19:39:18 +0000 (+0200)
Subject: slub: reduce overhead of slub_debug
X-Git-Tag: v3.1-rc1~328^2~4
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c4089f98e943ff445665dea49c190657b34ccffe;p=pandora-kernel.git

slub: reduce overhead of slub_debug

slub checks for poison one byte by one, which is highly inefficient
and shows up frequently as a highest cpu-eater in perf top.

Joining reads gives nice speedup:

(Compiling some project with different options)
                                 make -j12    make clean
slub_debug disabled:             1m 27s       1.2 s
slub_debug enabled:              1m 46s       7.6 s
slub_debug enabled + this patch: 1m 33s       3.2 s

check_bytes still shows up high, but not always at the top.

Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Matt Mackall <mpm@selenic.com>
Cc: linux-mm@kvack.org
Signed-off-by: Pekka Enberg <penberg@kernel.org>
---

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