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authorJens Axboe <jaxboe@fusionio.com>2011-04-16 15:51:05 +0400
committerJens Axboe <jaxboe@fusionio.com>2011-04-16 15:51:05 +0400
commit49cac01e1fa74174d72adb0e872504a7fefd7c01 (patch)
treea1ab1974eceea3179a604413955ad8369ba715d7 /block/blk-core.c
parenta237c1c5bc5dc5c76a21be922dca4826f3eca8ca (diff)
downloadlinux-49cac01e1fa74174d72adb0e872504a7fefd7c01.tar.xz
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 <jaxboe@fusionio.com>
Diffstat (limited to 'block/blk-core.c')
-rw-r--r--block/blk-core.c18
1 files changed, 12 insertions, 6 deletions
diff --git a/block/blk-core.c b/block/blk-core.c
index 3c8121072507..78b7b0cb7216 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -2662,17 +2662,23 @@ static int plug_rq_cmp(void *priv, struct list_head *a, struct list_head *b)
return !(rqa->q <= rqb->q);
}
+/*
+ * If 'from_schedule' is true, then postpone the dispatch of requests
+ * until a safe kblockd context. We due this to avoid accidental big
+ * additional stack usage in driver dispatch, in places where the originally
+ * plugger did not intend it.
+ */
static void queue_unplugged(struct request_queue *q, unsigned int depth,
- bool force_kblockd)
+ bool from_schedule)
{
- trace_block_unplug_io(q, depth);
- __blk_run_queue(q, force_kblockd);
+ trace_block_unplug(q, depth, !from_schedule);
+ __blk_run_queue(q, from_schedule);
if (q->unplugged_fn)
q->unplugged_fn(q);
}
-void blk_flush_plug_list(struct blk_plug *plug, bool force_kblockd)
+void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule)
{
struct request_queue *q;
unsigned long flags;
@@ -2707,7 +2713,7 @@ void blk_flush_plug_list(struct blk_plug *plug, bool force_kblockd)
BUG_ON(!rq->q);
if (rq->q != q) {
if (q) {
- queue_unplugged(q, depth, force_kblockd);
+ queue_unplugged(q, depth, from_schedule);
spin_unlock(q->queue_lock);
}
q = rq->q;
@@ -2728,7 +2734,7 @@ void blk_flush_plug_list(struct blk_plug *plug, bool force_kblockd)
}
if (q) {
- queue_unplugged(q, depth, force_kblockd);
+ queue_unplugged(q, depth, from_schedule);
spin_unlock(q->queue_lock);
}