diff options
Diffstat (limited to 'block/cfq-iosched.c')
| -rw-r--r-- | block/cfq-iosched.c | 91 |
1 files changed, 53 insertions, 38 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 7a8ef0f..d44402a 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -171,6 +171,7 @@ enum cfqq_state_flags { CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */ CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */ CFQ_CFQQ_FLAG_queue_new, /* queue never been serviced */ + CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */ }; #define CFQ_CFQQ_FNS(name) \ @@ -196,6 +197,7 @@ CFQ_CFQQ_FNS(fifo_expire); CFQ_CFQQ_FNS(idle_window); CFQ_CFQQ_FNS(prio_changed); CFQ_CFQQ_FNS(queue_new); +CFQ_CFQQ_FNS(slice_new); #undef CFQ_CFQQ_FNS static struct cfq_queue *cfq_find_cfq_hash(struct cfq_data *, unsigned int, unsigned short); @@ -231,6 +233,42 @@ static inline pid_t cfq_queue_pid(struct task_struct *task, int rw, int is_sync) } /* + * Scale schedule slice based on io priority. Use the sync time slice only + * if a queue is marked sync and has sync io queued. A sync queue with async + * io only, should not get full sync slice length. + */ +static inline int +cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) +{ + const int base_slice = cfqd->cfq_slice[cfq_cfqq_sync(cfqq)]; + + WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); + + return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - cfqq->ioprio)); +} + +static inline void +cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) +{ + cfqq->slice_end = cfq_prio_to_slice(cfqd, cfqq) + jiffies; +} + +/* + * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end + * isn't valid until the first request from the dispatch is activated + * and the slice time set. + */ +static inline int cfq_slice_used(struct cfq_queue *cfqq) +{ + if (cfq_cfqq_slice_new(cfqq)) + return 0; + if (time_before(jiffies, cfqq->slice_end)) + return 0; + + return 1; +} + +/* * Lifted from AS - choose which of rq1 and rq2 that is best served now. * We choose the request that is closest to the head right now. Distance * behind the head is penalized and only allowed to a certain extent. @@ -632,6 +670,7 @@ __cfq_set_active_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) cfqq->slice_left = 0; cfq_clear_cfqq_must_alloc_slice(cfqq); cfq_clear_cfqq_fifo_expire(cfqq); + cfq_mark_cfqq_slice_new(cfqq); } cfqd->active_queue = cfqq; @@ -660,7 +699,7 @@ __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq, * store what was left of this slice, if the queue idled out * or was preempted */ - if (time_after(cfqq->slice_end, now)) + if (cfq_slice_used(cfqq)) cfqq->slice_left = cfqq->slice_end - now; else cfqq->slice_left = 0; @@ -858,27 +897,6 @@ static inline struct request *cfq_check_fifo(struct cfq_queue *cfqq) return NULL; } -/* - * Scale schedule slice based on io priority. Use the sync time slice only - * if a queue is marked sync and has sync io queued. A sync queue with async - * io only, should not get full sync slice length. - */ -static inline int -cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) -{ - const int base_slice = cfqd->cfq_slice[cfq_cfqq_sync(cfqq)]; - - WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); - - return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - cfqq->ioprio)); -} - -static inline void -cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) -{ - cfqq->slice_end = cfq_prio_to_slice(cfqd, cfqq) + jiffies; -} - static inline int cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq) { @@ -894,7 +912,6 @@ cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq) */ static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd) { - unsigned long now = jiffies; struct cfq_queue *cfqq; cfqq = cfqd->active_queue; @@ -904,7 +921,7 @@ static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd) /* * slice has expired */ - if (!cfq_cfqq_must_dispatch(cfqq) && time_after(now, cfqq->slice_end)) + if (!cfq_cfqq_must_dispatch(cfqq) && cfq_slice_used(cfqq)) goto expire; /* @@ -913,7 +930,7 @@ static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd) */ if (!RB_EMPTY_ROOT(&cfqq->sort_list)) goto keep_queue; - else if (cfq_cfqq_dispatched(cfqq)) { + else if (cfq_cfqq_slice_new(cfqq) || cfq_cfqq_dispatched(cfqq)) { cfqq = NULL; goto keep_queue; } else if (cfq_cfqq_class_sync(cfqq)) { @@ -965,20 +982,15 @@ __cfq_dispatch_requests(struct cfq_data *cfqd, struct cfq_queue *cfqq, } while (dispatched < max_dispatch); /* - * if slice end isn't set yet, set it. - */ - if (!cfqq->slice_end) - cfq_set_prio_slice(cfqd, cfqq); - - /* * expire an async queue immediately if it has used up its slice. idle * queue always expire after 1 dispatch round. */ if ((!cfq_cfqq_sync(cfqq) && cfqd->dispatch_slice >= cfq_prio_to_maxrq(cfqd, cfqq)) || - cfq_class_idle(cfqq) || - !cfq_cfqq_idle_window(cfqq)) + cfq_class_idle(cfqq)) { + cfqq->slice_end = jiffies + 1; cfq_slice_expired(cfqd, 0); + } return dispatched; } @@ -1612,7 +1624,8 @@ static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) BUG_ON(!cfq_cfqq_on_rr(cfqq)); list_move(&cfqq->cfq_list, &cfqd->cur_rr); - cfqq->slice_end = cfqq->slice_left + jiffies; + cfqq->slice_end = 0; + cfq_mark_cfqq_slice_new(cfqq); } /* @@ -1722,7 +1735,11 @@ static void cfq_completed_request(request_queue_t *q, struct request *rq) * or if we want to idle in case it has no pending requests. */ if (cfqd->active_queue == cfqq) { - if (time_after(now, cfqq->slice_end)) + if (cfq_cfqq_slice_new(cfqq)) { + cfq_set_prio_slice(cfqd, cfqq); + cfq_clear_cfqq_slice_new(cfqq); + } + if (cfq_slice_used(cfqq)) cfq_slice_expired(cfqd, 0); else if (sync && RB_EMPTY_ROOT(&cfqq->sort_list)) { if (!cfq_arm_slice_timer(cfqd, cfqq)) @@ -1901,12 +1918,10 @@ static void cfq_idle_slice_timer(unsigned long data) spin_lock_irqsave(cfqd->queue->queue_lock, flags); if ((cfqq = cfqd->active_queue) != NULL) { - unsigned long now = jiffies; - /* * expired */ - if (time_after(now, cfqq->slice_end)) + if (cfq_slice_used(cfqq)) goto expire; /* |