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block: only force kblockd unplugging from the schedule() path

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For the explicit unplugging, we'd prefer to kick things off
immediately and not pay the penalty of the latency to switch
to kblockd. So let blk_finish_plug() do the run inline, while
the implicit-on-schedule-out unplug will punt to kblockd.

Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
This commit is contained in:
Jens Axboe 2011-04-15 15:49:07 +02:00
parent 88b996cd06
commit f6603783f9
2 changed files with 9 additions and 8 deletions
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13
block/blk-core.c
View file

@ -2662,16 +2662,17 @@ static int plug_rq_cmp(void *priv, struct list_head *a, struct list_head *b)
return !(rqa->q <= rqb->q);
}
static void queue_unplugged(struct request_queue *q, unsigned int depth)
static void queue_unplugged(struct request_queue *q, unsigned int depth,
bool force_kblockd)
{
trace_block_unplug_io(q, depth);
__blk_run_queue(q, true);
__blk_run_queue(q, force_kblockd);
if (q->unplugged_fn)
q->unplugged_fn(q);
}
void blk_flush_plug_list(struct blk_plug *plug)
void blk_flush_plug_list(struct blk_plug *plug, bool force_kblockd)
{
struct request_queue *q;
unsigned long flags;
@ -2706,7 +2707,7 @@ void blk_flush_plug_list(struct blk_plug *plug)
BUG_ON(!rq->q);
if (rq->q != q) {
if (q) {
queue_unplugged(q, depth);
queue_unplugged(q, depth, force_kblockd);
spin_unlock(q->queue_lock);
}
q = rq->q;
@ -2727,7 +2728,7 @@ void blk_flush_plug_list(struct blk_plug *plug)
}
if (q) {
queue_unplugged(q, depth);
queue_unplugged(q, depth, force_kblockd);
spin_unlock(q->queue_lock);
}
@ -2737,7 +2738,7 @@ EXPORT_SYMBOL(blk_flush_plug_list);
void blk_finish_plug(struct blk_plug *plug)
{
blk_flush_plug_list(plug);
blk_flush_plug_list(plug, false);
if (plug == current->plug)
current->plug = NULL;

4
include/linux/blkdev.h
View file

@ -865,14 +865,14 @@ struct blk_plug {
extern void blk_start_plug(struct blk_plug *);
extern void blk_finish_plug(struct blk_plug *);
extern void blk_flush_plug_list(struct blk_plug *);
extern void blk_flush_plug_list(struct blk_plug *, bool);
static inline void blk_flush_plug(struct task_struct *tsk)
{
struct blk_plug *plug = tsk->plug;
if (plug)
blk_flush_plug_list(plug);
blk_flush_plug_list(plug, true);
}
static inline bool blk_needs_flush_plug(struct task_struct *tsk)