cfq-iosched: Add additional blktrace log messages in CFQ for easier debugging
authorDivyesh Shah <dpshah@google.com>
Thu, 25 Mar 2010 14:45:03 +0000 (15:45 +0100)
committerJens Axboe <jens.axboe@oracle.com>
Thu, 25 Mar 2010 14:45:03 +0000 (15:45 +0100)
These have helped us debug some issues we've noticed in earlier IO
controller versions and should be useful now as well. The extra logging
covers:
- idling behavior. Since there are so many conditions based on which we decide
to idle or not, this patch adds a log message for some conditions that we've
found useful.
- workload slices and current prio and workload type

Changelog from v1:
o moved log message from cfq_set_active_queue() to __cfq_set_active_queue()
o changed queue_count to st->count

Signed-off-by: Divyesh Shah<dpshah@google.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
block/cfq-iosched.c

index 8d5a2f2f7fb9029315cfd12643a34625992ab181..2f91c53519498f6aee0f2b224720e6d6614aab65 100644 (file)
@@ -1518,7 +1518,8 @@ static void __cfq_set_active_queue(struct cfq_data *cfqd,
                                   struct cfq_queue *cfqq)
 {
        if (cfqq) {
-               cfq_log_cfqq(cfqd, cfqq, "set_active");
+               cfq_log_cfqq(cfqd, cfqq, "set_active wl_prio:%d wl_type:%d",
+                               cfqd->serving_prio, cfqd->serving_type);
                cfqq->slice_start = 0;
                cfqq->dispatch_start = jiffies;
                cfqq->allocated_slice = 0;
@@ -1788,7 +1789,11 @@ static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
         * Otherwise, we do only if they are the last ones
         * in their service tree.
         */
-       return service_tree->count == 1 && cfq_cfqq_sync(cfqq);
+       if (service_tree->count == 1 && cfq_cfqq_sync(cfqq))
+               return 1;
+       cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d",
+                       service_tree->count);
+       return 0;
 }
 
 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
@@ -1833,8 +1838,11 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd)
         * time slice.
         */
        if (sample_valid(cic->ttime_samples) &&
-           (cfqq->slice_end - jiffies < cic->ttime_mean))
+           (cfqq->slice_end - jiffies < cic->ttime_mean)) {
+               cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%d",
+                               cic->ttime_mean);
                return;
+       }
 
        cfq_mark_cfqq_wait_request(cfqq);
 
@@ -2042,6 +2050,7 @@ static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
                slice = max(slice, 2 * cfqd->cfq_slice_idle);
 
        slice = max_t(unsigned, slice, CFQ_MIN_TT);
+       cfq_log(cfqd, "workload slice:%d", slice);
        cfqd->workload_expires = jiffies + slice;
        cfqd->noidle_tree_requires_idle = false;
 }
@@ -3308,6 +3317,7 @@ static void cfq_completed_request(struct request_queue *q, struct request *rq)
                if (cfq_should_wait_busy(cfqd, cfqq)) {
                        cfqq->slice_end = jiffies + cfqd->cfq_slice_idle;
                        cfq_mark_cfqq_wait_busy(cfqq);
+                       cfq_log_cfqq(cfqd, cfqq, "will busy wait");
                }
 
                /*