Merge branch 'omap-clock-fixes' of git://git.pwsan.com/linux-2.6

[linux-2.6-omap-h63xx.git] / block / cfq-iosched.c

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 11efcf196e74b7a034a89217e712d696f9cc8d5a..a4809de6fea656a4ac6091f6c61c38f536a4f766 100644 (file)
--- 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
@@ -2174,6 +2177,12 @@ static void cfq_idle_slice_timer(unsigned long data)
        if (cfqq) {
                timed_out = 0;
 
+               /*
+                * We saw a request before the queue expired, let it through
+                */
+               if (cfq_cfqq_must_dispatch(cfqq))
+                       goto out_kick;
+
                /*
                 * expired
                 */