diff options
| author | Shaohua Li <shaohua.li@intel.com> | 2010-11-08 15:01:03 +0100 |
|---|---|---|
| committer | Jens Axboe <jaxboe@fusionio.com> | 2010-11-08 15:01:03 +0100 |
| commit | d2d59e18a1ea8ecdd1c0a52af320e9a7f5391cc4 (patch) | |
| tree | b39812dc8fd9ae552c361a84a10dcd61d2caaab5 | |
| parent | c1e44756fdb7b363fd22cb5514dced40752e36c5 (diff) | |
| download | linux-d2d59e18a1ea8ecdd1c0a52af320e9a7f5391cc4.tar.bz2 | |
cfq-iosched: schedule dispatch for noidle queue
A queue is idle at cfq_dispatch_requests(), but it gets noidle later. Unless
other task explictly does unplug or all requests are drained, we will not
deliever requests to the disk even cfq_arm_slice_timer doesn't make the
queue idle. For example, cfq_should_idle() returns true because of
service_tree->count == 1, and then other queues are added. Note, I didn't
see obvious performance impacts so far with the patch, but just thought
this could be a problem.
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
| -rw-r--r-- | block/cfq-iosched.c | 23 |
1 files changed, 22 insertions, 1 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index b8174bb4a6a1..986865e3fbc5 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -3255,6 +3255,10 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq)) return true; + /* An idle queue should not be idle now for some reason */ + if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq)) + return true; + if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq)) return false; @@ -3508,8 +3512,25 @@ static void cfq_completed_request(struct request_queue *q, struct request *rq) } } - if (!cfqd->rq_in_driver) + if (!cfqd->rq_in_driver) { + cfq_schedule_dispatch(cfqd); + return; + } + /* + * A queue is idle at cfq_dispatch_requests(), but it gets noidle + * later. We schedule a dispatch if the queue has no requests, + * otherwise the disk is actually in idle till all requests + * are finished even cfq_arm_slice_timer doesn't make the queue idle + * */ + cfqq = cfqd->active_queue; + if (!cfqq) + return; + + if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq) && + (!cfqd->cfq_group_idle || cfqq->cfqg->nr_cfqq > 1)) { + cfq_del_timer(cfqd, cfqq); cfq_schedule_dispatch(cfqd); + } } /* |