aboutsummaryrefslogtreecommitdiffstats
path: root/block
diff options
context:
space:
mode:
Diffstat (limited to 'block')
-rw-r--r--block/cfq-iosched.c25
1 files changed, 17 insertions, 8 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 11efcf196e7..a4809de6fea 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -177,6 +177,7 @@ struct cfq_queue {
enum cfqq_state_flags {
CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
+ CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */
CFQ_CFQQ_FLAG_must_alloc, /* must be allowed rq alloc */
CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
@@ -202,6 +203,7 @@ static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
CFQ_CFQQ_FNS(on_rr);
CFQ_CFQQ_FNS(wait_request);
+CFQ_CFQQ_FNS(must_dispatch);
CFQ_CFQQ_FNS(must_alloc);
CFQ_CFQQ_FNS(must_alloc_slice);
CFQ_CFQQ_FNS(fifo_expire);
@@ -774,6 +776,7 @@ static void __cfq_set_active_queue(struct cfq_data *cfqd,
cfqq->slice_dispatch = 0;
cfq_clear_cfqq_wait_request(cfqq);
+ cfq_clear_cfqq_must_dispatch(cfqq);
cfq_clear_cfqq_must_alloc_slice(cfqq);
cfq_clear_cfqq_fifo_expire(cfqq);
cfq_mark_cfqq_slice_new(cfqq);
@@ -1009,7 +1012,7 @@ static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
/*
* The active queue has run out of time, expire it and select new.
*/
- if (cfq_slice_used(cfqq))
+ if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq))
goto expire;
/*
@@ -1173,6 +1176,7 @@ static int cfq_dispatch_requests(struct request_queue *q, int force)
*/
cfq_dispatch_request(cfqd, cfqq);
cfqq->slice_dispatch++;
+ cfq_clear_cfqq_must_dispatch(cfqq);
/*
* expire an async queue immediately if it has used up its slice. idle
@@ -1898,14 +1902,13 @@ cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
if (cfqq == cfqd->active_queue) {
/*
- * if we are waiting for a request for this queue, let it rip
- * immediately and flag that we must not expire this queue
- * just now
+ * Remember that we saw a request from this process, but
+ * don't start queuing just yet. Otherwise we risk seeing lots
+ * of tiny requests, because we disrupt the normal plugging
+ * and merging.
*/
- if (cfq_cfqq_wait_request(cfqq)) {
- del_timer(&cfqd->idle_slice_timer);
- blk_start_queueing(cfqd->queue);
- }
+ if (cfq_cfqq_wait_request(cfqq))
+ cfq_mark_cfqq_must_dispatch(cfqq);
} else if (cfq_should_preempt(cfqd, cfqq, rq)) {
/*
* not the active queue - expire current slice if it is
@@ -2175,6 +2178,12 @@ static void cfq_idle_slice_timer(unsigned long data)
timed_out = 0;
/*
+ * We saw a request before the queue expired, let it through
+ */
+ if (cfq_cfqq_must_dispatch(cfqq))
+ goto out_kick;
+
+ /*
* expired
*/
if (cfq_slice_used(cfqq))