From: Andi Kleen <ak@linux.intel.com>
Date: Tue, 2 Aug 2011 04:38:08 +0000 (-0700)
Subject: direct-io: inline the complete submission path
X-Git-Tag: v3.2-rc1~131^2~6
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ba253fbf6d3502c54e1ac8792e7ac8290a1f5b8d;p=pandora-kernel.git

direct-io: inline the complete submission path

Add inlines to all the submission path functions. While this increases
code size it also gives gcc a lot of optimization opportunities
in this critical hotpath.

In particular -- together with some other changes -- this
allows gcc to get rid of the unnecessary clearing of
sdio at the beginning and optimize the messy parameter passing.
Any non inlining of a function which takes a sdio parameter
would break this optimization because they cannot be done if the
address of a structure is taken.

Note that benefits are only seen with CONFIG_OPTIMIZE_INLINING
and CONFIG_CC_OPTIMIZE_FOR_SIZE both set to off.

This gives about 2.2% improvement on a large database benchmark
with a high IOPS rate.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
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