From: Jens Axboe Date: Sat, 13 Sep 2008 18:26:01 +0000 (+0200) Subject: block: add support for IO CPU affinity X-Git-Tag: v2.6.28-rc1~733^2~74 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c7c22e4d5c1fdebfac4dba76de7d0338c2b0d832;p=pandora-kernel.git block: add support for IO CPU affinity This patch adds support for controlling the IO completion CPU of either all requests on a queue, or on a per-request basis. We export a sysfs variable (rq_affinity) which, if set, migrates completions of requests to the CPU that originally submitted it. A bio helper (bio_set_completion_cpu()) is also added, so that queuers can ask for completion on that specific CPU. In testing, this has been show to cut the system time by as much as 20-40% on synthetic workloads where CPU affinity is desired. This requires a little help from the architecture, so it'll only work as designed for archs that are using the new generic smp helper infrastructure. Signed-off-by: Jens Axboe --- Reading git-diff-tree failed