From 73c101011926c5832e6e141682180c4debe2cf45 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Tue, 8 Mar 2011 13:19:51 +0100 Subject: block: initial patch for on-stack per-task plugging This patch adds support for creating a queuing context outside of the queue itself. This enables us to batch up pieces of IO before grabbing the block device queue lock and submitting them to the IO scheduler. The context is created on the stack of the process and assigned in the task structure, so that we can auto-unplug it if we hit a schedule event. The current queue plugging happens implicitly if IO is submitted to an empty device, yet callers have to remember to unplug that IO when they are going to wait for it. This is an ugly API and has caused bugs in the past. Additionally, it requires hacks in the vm (->sync_page() callback) to handle that logic. By switching to an explicit plugging scheme we make the API a lot nicer and can get rid of the ->sync_page() hack in the vm. Signed-off-by: Jens Axboe --- block/blk-flush.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'block/blk-flush.c') diff --git a/block/blk-flush.c b/block/blk-flush.c index a867e3f524f3..1e2aa8a8908c 100644 --- a/block/blk-flush.c +++ b/block/blk-flush.c @@ -264,10 +264,9 @@ static bool blk_kick_flush(struct request_queue *q) static void flush_data_end_io(struct request *rq, int error) { struct request_queue *q = rq->q; - bool was_empty = elv_queue_empty(q); /* after populating an empty queue, kick it to avoid stall */ - if (blk_flush_complete_seq(rq, REQ_FSEQ_DATA, error) && was_empty) + if (blk_flush_complete_seq(rq, REQ_FSEQ_DATA, error)) __blk_run_queue(q); } -- cgit From 7eaceaccab5f40bbfda044629a6298616aeaed50 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Thu, 10 Mar 2011 08:52:07 +0100 Subject: block: remove per-queue plugging Code has been converted over to the new explicit on-stack plugging, and delay users have been converted to use the new API for that. So lets kill off the old plugging along with aops->sync_page(). Signed-off-by: Jens Axboe --- block/blk-flush.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'block/blk-flush.c') diff --git a/block/blk-flush.c b/block/blk-flush.c index 1e2aa8a8908c..671fa9da7560 100644 --- a/block/blk-flush.c +++ b/block/blk-flush.c @@ -194,7 +194,6 @@ static void flush_end_io(struct request *flush_rq, int error) { struct request_queue *q = flush_rq->q; struct list_head *running = &q->flush_queue[q->flush_running_idx]; - bool was_empty = elv_queue_empty(q); bool queued = false; struct request *rq, *n; @@ -213,7 +212,7 @@ static void flush_end_io(struct request *flush_rq, int error) } /* after populating an empty queue, kick it to avoid stall */ - if (queued && was_empty) + if (queued) __blk_run_queue(q); } -- cgit