From: Jens Axboe Date: Wed, 19 Nov 2008 13:38:39 +0000 (+0100) Subject: block: leave request timeout timer running on an empty list References: bnc#447249 X-Git-Tag: next-20081124~22^2~5 X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Fsfr%2Flinux-next.git;a=commitdiff_plain;h=4fc4d9c3fc9091db5a9fc534bd1c86bb338aff9f block: leave the request timeout timer running even on an empty list For sync IO, we'll often do them serialized. This means we'll be touching the queue timer for every IO, as opposed to only occasionally like we do for queued IO. Instead of deleting the timer when the last request is removed, just let continue running. If a new request comes up soon we then don't have to readd the timer again. If no new requests arrive, the timer will expire without side effect later. This improves high iops sync IO by ~1%. Signed-off-by: Jens Axboe Signed-off-by: Hannes Reinecke --- --- block/blk-core.c | 1 + block/blk-timeout.c | 3 --- 2 files changed, 1 insertion(+), 3 deletions(-) --- a/block/blk-core.c +++ b/block/blk-core.c @@ -393,6 +393,7 @@ EXPORT_SYMBOL(blk_stop_queue); void blk_sync_queue(struct request_queue *q) { del_timer_sync(&q->unplug_timer); + del_timer_sync(&q->timeout); kblockd_flush_work(&q->unplug_work); } EXPORT_SYMBOL(blk_sync_queue); --- a/block/blk-timeout.c +++ b/block/blk-timeout.c @@ -14,11 +14,7 @@ */ void blk_delete_timer(struct request *req) { - struct request_queue *q = req->q; - list_del_init(&req->timeout_list); - if (list_empty(&q->timeout_list)) - del_timer(&q->timeout); } static void blk_rq_timed_out(struct request *req)