From: David Chinner <dgc@sgi.com>
Date: Thu, 6 Mar 2008 02:45:35 +0000 (+1100)
Subject: [XFS] Use atomic counters for ktrace buffer indexes
X-Git-Tag: v2.6.26-rc1~1147^2~70
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6ee4752ffe782be6e86bea1403a2fe0f682aa71a;p=pandora-kernel.git

[XFS] Use atomic counters for ktrace buffer indexes

ktrace_enter() is consuming vast amounts of CPU time due to the use of a
single global lock for protecting buffer index increments. Change it to
use per-buffer atomic counters - this reduces ktrace_enter() overhead
during a trace intensive test on a 4p machine from 58% of all CPU time to
12% and halves test runtime.

SGI-PV: 977546
SGI-Modid: xfs-linux-melb:xfs-kern:30537a

Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
---

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