From: Shaohua Li Date: Wed, 24 Aug 2011 14:04:32 +0000 (+0200) Subject: block: change force plug flush call order X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=a63271627521b825b0dd0a564e9a9c62b4c1ca89;p=linux-beck.git block: change force plug flush call order Do blk_flush_plug_list() first and then add new request aDo blk_flush_plug_list() first and then add new request aDo blk_flush_plug_list() first and then add new request at the tail. New request can't be merged to existing requests, but later new requests might be merged with this new one. If blk_flush_plug_list() is done later, the merge doesn't happen. Believe it or not, this fixes a 10% regression running sysbench workload. Signed-off-by: Shaohua Li Signed-off-by: Shaohua Li Signed-off-by: Jens Axboe --- diff --git a/block/blk-core.c b/block/blk-core.c index 90e1ffdeb415..67dba6941194 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -1302,11 +1302,11 @@ get_rq: if (__rq->q != q) plug->should_sort = 1; } - list_add_tail(&req->queuelist, &plug->list); - plug->count++; - drive_stat_acct(req, 1); if (plug->count >= BLK_MAX_REQUEST_COUNT) blk_flush_plug_list(plug, false); + plug->count++; + list_add_tail(&req->queuelist, &plug->list); + drive_stat_acct(req, 1); } else { spin_lock_irq(q->queue_lock); add_acct_request(q, req, where);