diff options
| -rw-r--r-- | block/cfq-iosched.c | 121 |
1 files changed, 67 insertions, 54 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 690ebd96dc42..5c3cee93329a 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -1247,67 +1247,21 @@ static int cfq_forced_dispatch(struct cfq_data *cfqd) return dispatched; } -/* - * Dispatch a request from cfqq, moving them to the request queue - * dispatch list. - */ -static void cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq) +static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq) { - struct request *rq; - - BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list)); - - /* - * follow expired path, else get first next available - */ - rq = cfq_check_fifo(cfqq); - if (!rq) - rq = cfqq->next_rq; - - /* - * insert request into driver dispatch list - */ - cfq_dispatch_insert(cfqd->queue, rq); - - if (!cfqd->active_cic) { - struct cfq_io_context *cic = RQ_CIC(rq); - - atomic_long_inc(&cic->ioc->refcount); - cfqd->active_cic = cic; - } -} - -/* - * Find the cfqq that we need to service and move a request from that to the - * dispatch list - */ -static int cfq_dispatch_requests(struct request_queue *q, int force) -{ - struct cfq_data *cfqd = q->elevator->elevator_data; - struct cfq_queue *cfqq; unsigned int max_dispatch; - if (!cfqd->busy_queues) - return 0; - - if (unlikely(force)) - return cfq_forced_dispatch(cfqd); - - cfqq = cfq_select_queue(cfqd); - if (!cfqq) - return 0; - /* * Drain async requests before we start sync IO */ if (cfq_cfqq_idle_window(cfqq) && cfqd->rq_in_driver[BLK_RW_ASYNC]) - return 0; + return false; /* * If this is an async queue and we have sync IO in flight, let it wait */ if (cfqd->sync_flight && !cfq_cfqq_sync(cfqq)) - return 0; + return false; max_dispatch = cfqd->cfq_quantum; if (cfq_class_idle(cfqq)) @@ -1321,13 +1275,13 @@ static int cfq_dispatch_requests(struct request_queue *q, int force) * idle queue must always only have a single IO in flight */ if (cfq_class_idle(cfqq)) - return 0; + return false; /* * We have other queues, don't allow more IO from this one */ if (cfqd->busy_queues > 1) - return 0; + return false; /* * Sole queue user, allow bigger slice @@ -1351,13 +1305,72 @@ static int cfq_dispatch_requests(struct request_queue *q, int force) max_dispatch = depth; } - if (cfqq->dispatched >= max_dispatch) + /* + * If we're below the current max, allow a dispatch + */ + return cfqq->dispatched < max_dispatch; +} + +/* + * Dispatch a request from cfqq, moving them to the request queue + * dispatch list. + */ +static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq) +{ + struct request *rq; + + BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list)); + + if (!cfq_may_dispatch(cfqd, cfqq)) + return false; + + /* + * follow expired path, else get first next available + */ + rq = cfq_check_fifo(cfqq); + if (!rq) + rq = cfqq->next_rq; + + /* + * insert request into driver dispatch list + */ + cfq_dispatch_insert(cfqd->queue, rq); + + if (!cfqd->active_cic) { + struct cfq_io_context *cic = RQ_CIC(rq); + + atomic_long_inc(&cic->ioc->refcount); + cfqd->active_cic = cic; + } + + return true; +} + +/* + * Find the cfqq that we need to service and move a request from that to the + * dispatch list + */ +static int cfq_dispatch_requests(struct request_queue *q, int force) +{ + struct cfq_data *cfqd = q->elevator->elevator_data; + struct cfq_queue *cfqq; + + if (!cfqd->busy_queues) + return 0; + + if (unlikely(force)) + return cfq_forced_dispatch(cfqd); + + cfqq = cfq_select_queue(cfqd); + if (!cfqq) return 0; /* - * Dispatch a request from this cfqq + * Dispatch a request from this cfqq, if it is allowed */ - cfq_dispatch_request(cfqd, cfqq); + if (!cfq_dispatch_request(cfqd, cfqq)) + return 0; + cfqq->slice_dispatch++; cfq_clear_cfqq_must_dispatch(cfqq); |