From: Paul Jackson <pj@sgi.com>
Date: Sun, 8 Jan 2006 09:02:04 +0000 (-0800)
Subject: [PATCH] cpuset: skip rcu check if task is in root cpuset
X-Git-Tag: v2.6.16-rc1~815
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=03a285f58064b8e0af08383e082e383753d9c33e;p=pandora-kernel.git

[PATCH] cpuset: skip rcu check if task is in root cpuset

For systems that aren't using cpusets, but have them CONFIG_CPUSET enabled in
their kernel (eventually this may be most distribution kernels), this patch
removes even the minimal rcu_read_lock() from the memory page allocation path.

Actually, it removes that rcu call for any task that is in the root cpuset
(top_cpuset), which on systems not actively using cpusets, is all tasks.

We don't need the rcu check for tasks in the top_cpuset, because the
top_cpuset is statically allocated, so at no risk of being freed out from
underneath us.

Signed-off-by: Paul Jackson <pj@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---

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