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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 /fs
parent18887ad910e56066233a07fd3cfb2fa11338b782 (diff)
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 'fs')
-rw-r--r--fs/bio.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/fs/bio.c b/fs/bio.c
index bee4deca774..6a637b5c24b 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -111,6 +111,7 @@ void bio_init(struct bio *bio)
{
memset(bio, 0, sizeof(*bio));
bio->bi_flags = 1 << BIO_UPTODATE;
+ bio->bi_comp_cpu = -1;
atomic_set(&bio->bi_cnt, 1);
}