cfq-iosched: Get rid of cfqq wait_busy_done flag
Vivek Goyal [Tue, 8 Dec 2009 22:52:57 +0000 (17:52 -0500)]
o Get rid of wait_busy_done flag. This flag only tells we were doing wait
  busy on a queue and that queue got request so expire it. That information
  can easily be obtained by (cfq_cfqq_wait_busy() && queue_is_not_empty). So
  remove this flag and keep code simple.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

block/cfq-iosched.c

index b19cd68..f41fdb5 100644 (file)
@@ -319,7 +319,6 @@ enum cfqq_state_flags {
        CFQ_CFQQ_FLAG_coop,             /* cfqq is shared */
        CFQ_CFQQ_FLAG_deep,             /* sync cfqq experienced large depth */
        CFQ_CFQQ_FLAG_wait_busy,        /* Waiting for next request */
-       CFQ_CFQQ_FLAG_wait_busy_done,   /* Got new request. Expire the queue */
 };
 
 #define CFQ_CFQQ_FNS(name)                                             \
@@ -348,7 +347,6 @@ CFQ_CFQQ_FNS(sync);
 CFQ_CFQQ_FNS(coop);
 CFQ_CFQQ_FNS(deep);
 CFQ_CFQQ_FNS(wait_busy);
-CFQ_CFQQ_FNS(wait_busy_done);
 #undef CFQ_CFQQ_FNS
 
 #ifdef CONFIG_DEBUG_CFQ_IOSCHED
@@ -1574,7 +1572,6 @@ __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
 
        cfq_clear_cfqq_wait_request(cfqq);
        cfq_clear_cfqq_wait_busy(cfqq);
-       cfq_clear_cfqq_wait_busy_done(cfqq);
 
        /*
         * store what was left of this slice, if the queue idled/timed out
@@ -2134,11 +2131,17 @@ static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
 
        if (!cfqd->rq_queued)
                return NULL;
+
+       /*
+        * We were waiting for group to get backlogged. Expire the queue
+        */
+       if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list))
+               goto expire;
+
        /*
         * The active queue has run out of time, expire it and select new.
         */
-       if ((cfq_slice_used(cfqq) || cfq_cfqq_wait_busy_done(cfqq))
-            && !cfq_cfqq_must_dispatch(cfqq))
+       if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq))
                goto expire;
 
        /*
@@ -3171,10 +3174,6 @@ cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
        cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
 
        if (cfqq == cfqd->active_queue) {
-               if (cfq_cfqq_wait_busy(cfqq)) {
-                       cfq_clear_cfqq_wait_busy(cfqq);
-                       cfq_mark_cfqq_wait_busy_done(cfqq);
-               }
                /*
                 * Remember that we saw a request from this process, but
                 * don't start queuing just yet. Otherwise we risk seeing lots