From a237c1c5bc5dc5c76a21be922dca4826f3eca8ca Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Sat, 16 Apr 2011 13:27:55 +0200 Subject: block: let io_schedule() flush the plug inline Linus correctly observes that the most important dispatch cases are now done from kblockd, this isn't ideal for latency reasons. The original reason for switching dispatches out-of-line was to avoid too deep a stack, so by _only_ letting the "accidental" flush directly in schedule() be guarded by offload to kblockd, we should be able to get the best of both worlds. So add a blk_schedule_flush_plug() that offloads to kblockd, and only use that from the schedule() path. Signed-off-by: Jens Axboe --- include/linux/blkdev.h | 13 +++++++++++++ 1 file changed, 13 insertions(+) (limited to 'include') diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 1c76506fcf11..ec0357d8c4a5 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -871,6 +871,14 @@ static inline void blk_flush_plug(struct task_struct *tsk) { struct blk_plug *plug = tsk->plug; + if (plug) + blk_flush_plug_list(plug, false); +} + +static inline void blk_schedule_flush_plug(struct task_struct *tsk) +{ + struct blk_plug *plug = tsk->plug; + if (plug) blk_flush_plug_list(plug, true); } @@ -1317,6 +1325,11 @@ static inline void blk_flush_plug(struct task_struct *task) { } +static inline void blk_schedule_flush_plug(struct task_struct *task) +{ +} + + static inline bool blk_needs_flush_plug(struct task_struct *tsk) { return false; -- cgit v1.2.1 From 49cac01e1fa74174d72adb0e872504a7fefd7c01 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Sat, 16 Apr 2011 13:51:05 +0200 Subject: block: make unplug timer trace event correspond to the schedule() unplug It's a pretty close match to what we had before - the timer triggering would mean that nobody unplugged the plug in due time, in the new scheme this matches very closely what the schedule() unplug now is. It's essentially the difference between an explicit unplug (IO unplug) or an implicit unplug (timer unplug, we scheduled with pending IO queued). Signed-off-by: Jens Axboe --- include/trace/events/block.h | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) (limited to 'include') diff --git a/include/trace/events/block.h b/include/trace/events/block.h index 006e60b58306..bf366547da25 100644 --- a/include/trace/events/block.h +++ b/include/trace/events/block.h @@ -401,9 +401,9 @@ TRACE_EVENT(block_plug, DECLARE_EVENT_CLASS(block_unplug, - TP_PROTO(struct request_queue *q, unsigned int depth), + TP_PROTO(struct request_queue *q, unsigned int depth, bool explicit), - TP_ARGS(q, depth), + TP_ARGS(q, depth, explicit), TP_STRUCT__entry( __field( int, nr_rq ) @@ -419,18 +419,19 @@ DECLARE_EVENT_CLASS(block_unplug, ); /** - * block_unplug_io - release of operations requests in request queue + * block_unplug - release of operations requests in request queue * @q: request queue to unplug * @depth: number of requests just added to the queue + * @explicit: whether this was an explicit unplug, or one from schedule() * * Unplug request queue @q because device driver is scheduled to work * on elements in the request queue. */ -DEFINE_EVENT(block_unplug, block_unplug_io, +DEFINE_EVENT(block_unplug, block_unplug, - TP_PROTO(struct request_queue *q, unsigned int depth), + TP_PROTO(struct request_queue *q, unsigned int depth, bool explicit), - TP_ARGS(q, depth) + TP_ARGS(q, depth, explicit) ); /** -- cgit v1.2.1