From: Michael S. Tsirkin <mst@redhat.com>
Date: Tue, 22 Sep 2009 00:03:52 +0000 (-0700)
Subject: mm: reduce atomic use on use_mm fast path
X-Git-Tag: v2.6.32-rc1~472
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f68e14805085972b4e0b0ab684af37f713b9c262;p=pandora-kernel.git

mm: reduce atomic use on use_mm fast path

When the mm being switched to matches the active mm, we don't need to
increment and then drop the mm count.  In a simple benchmark this happens
in about 50% of time.  Making that conditional reduces contention on that
cacheline on SMP systems.

Acked-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

Reading git-diff-tree failed