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authorJens Axboe <jens.axboe@oracle.com>2008-09-13 20:26:01 +0200
committerJens Axboe <jens.axboe@oracle.com>2008-10-09 08:56:09 +0200
commitc7c22e4d5c1fdebfac4dba76de7d0338c2b0d832 (patch)
treeecc3d2517b3471ccc35d4cb4e3b48d4b57205061 /block/blk-settings.c
parent18887ad910e56066233a07fd3cfb2fa11338b782 (diff)
downloadlinux-2.6.34-ux500-c7c22e4d5c1fdebfac4dba76de7d0338c2b0d832.tar.gz
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 <jens.axboe@oracle.com>
Diffstat (limited to 'block/blk-settings.c')
-rw-r--r--block/blk-settings.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/block/blk-settings.c b/block/blk-settings.c
index d70692badcd..a60e959a12c 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -443,7 +443,7 @@ void blk_queue_update_dma_alignment(struct request_queue *q, int mask)
}
EXPORT_SYMBOL(blk_queue_update_dma_alignment);
-static int __init blk_settings_init(void)
+int __init blk_settings_init(void)
{
blk_max_low_pfn = max_low_pfn - 1;
blk_max_pfn = max_pfn - 1;