struct list_head fifo;
unsigned long slice_end;
- unsigned long slice_left;
unsigned long service_last;
+ long slice_resid;
/* number of requests that are on the dispatch list */
int on_dispatch[2];
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) \
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);
return CFQ_KEY_ASYNC;
}
+/*
+ * 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;
+ cfqq->slice_end += cfqq->slice_resid;
+
+ /*
+ * Don't carry over residual for more than one slice, we only want
+ * to slightly correct the fairness. Carrying over forever would
+ * easily introduce oscillations.
+ */
+ cfqq->slice_resid = 0;
+}
+
+/*
+ * 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
del_timer(&cfqd->idle_class_timer);
cfqq->slice_end = 0;
- 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;
*/
static void
__cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
- int preempted)
+ int preempted, int timed_out)
{
- unsigned long now = jiffies;
-
if (cfq_cfqq_wait_request(cfqq))
del_timer(&cfqd->idle_slice_timer);
- if (!preempted && !cfq_cfqq_dispatched(cfqq))
- cfq_schedule_dispatch(cfqd);
-
cfq_clear_cfqq_must_dispatch(cfqq);
cfq_clear_cfqq_wait_request(cfqq);
cfq_clear_cfqq_queue_new(cfqq);
* store what was left of this slice, if the queue idled out
* or was preempted
*/
- if (time_after(cfqq->slice_end, now))
- cfqq->slice_left = cfqq->slice_end - now;
- else
- cfqq->slice_left = 0;
+ if (timed_out && !cfq_cfqq_slice_new(cfqq))
+ cfqq->slice_resid = cfqq->slice_end - jiffies;
cfq_resort_rr_list(cfqq, preempted);
cfqd->dispatch_slice = 0;
}
-static inline void cfq_slice_expired(struct cfq_data *cfqd, int preempted)
+static inline void cfq_slice_expired(struct cfq_data *cfqd, int preempted,
+ int timed_out)
{
struct cfq_queue *cfqq = cfqd->active_queue;
if (cfqq)
- __cfq_slice_expired(cfqd, cfqq, preempted);
+ __cfq_slice_expired(cfqd, cfqq, preempted, timed_out);
}
/*
#define CIC_SEEKY(cic) ((cic)->seek_mean > (128 * 1024))
-static int cfq_arm_slice_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
-
+static int cfq_arm_slice_timer(struct cfq_data *cfqd)
{
+ struct cfq_queue *cfqq = cfqd->active_queue;
struct cfq_io_context *cic;
unsigned long sl;
WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
- WARN_ON(cfqq != cfqd->active_queue);
/*
* idle is disabled, either manually or by past process history
if (cfq_cfqq_fifo_expire(cfqq))
return NULL;
+
+ cfq_mark_cfqq_fifo_expire(cfqq);
+
if (list_empty(&cfqq->fifo))
return NULL;
fifo = cfq_cfqq_class_sync(cfqq);
rq = rq_entry_fifo(cfqq->fifo.next);
- if (time_after(jiffies, rq->start_time + cfqd->cfq_fifo_expire[fifo])) {
- cfq_mark_cfqq_fifo_expire(cfqq);
+ if (time_after(jiffies, rq->start_time + cfqd->cfq_fifo_expire[fifo]))
return rq;
- }
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)
{
*/
static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
{
- unsigned long now = jiffies;
struct cfq_queue *cfqq;
cfqq = cfqd->active_queue;
/*
* 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;
/*
*/
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)) {
- if (cfq_arm_slice_timer(cfqd, cfqq))
+ if (cfq_arm_slice_timer(cfqd))
return NULL;
}
expire:
- cfq_slice_expired(cfqd, 0);
+ cfq_slice_expired(cfqd, 0, 0);
new_queue:
cfqq = cfq_set_active_queue(cfqd);
keep_queue:
} 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_slice_expired(cfqd, 0);
+ cfq_class_idle(cfqq)) {
+ cfqq->slice_end = jiffies + 1;
+ cfq_slice_expired(cfqd, 0, 0);
+ }
return dispatched;
}
dispatched += cfq_forced_dispatch_cfqqs(&cfqd->cur_rr);
dispatched += cfq_forced_dispatch_cfqqs(&cfqd->idle_rr);
- cfq_slice_expired(cfqd, 0);
+ cfq_slice_expired(cfqd, 0, 0);
BUG_ON(cfqd->busy_queues);
if (prev_cfqq == cfqq)
break;
+ /*
+ * So we have dispatched before in this round, if the
+ * next queue has idling enabled (must be sync), don't
+ * allow it service until the previous have continued.
+ */
+ if (cfqd->rq_in_driver && cfq_cfqq_idle_window(cfqq))
+ break;
+
cfq_clear_cfqq_must_dispatch(cfqq);
cfq_clear_cfqq_wait_request(cfqq);
del_timer(&cfqd->idle_slice_timer);
max_dispatch = 1;
dispatched += __cfq_dispatch_requests(cfqd, cfqq, max_dispatch);
-
- /*
- * If the dispatch cfqq has idling enabled and is still
- * the active queue, break out.
- */
- if (cfq_cfqq_idle_window(cfqq) && cfqd->active_queue)
- break;
-
prev_cfqq = cfqq;
}
BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
BUG_ON(cfq_cfqq_on_rr(cfqq));
- if (unlikely(cfqd->active_queue == cfqq))
- __cfq_slice_expired(cfqd, cfqq, 0);
+ if (unlikely(cfqd->active_queue == cfqq)) {
+ __cfq_slice_expired(cfqd, cfqq, 0, 0);
+ cfq_schedule_dispatch(cfqd);
+ }
/*
* it's on the empty list and still hashed
static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
- if (unlikely(cfqq == cfqd->active_queue))
- __cfq_slice_expired(cfqd, cfqq, 0);
+ if (unlikely(cfqq == cfqd->active_queue)) {
+ __cfq_slice_expired(cfqd, cfqq, 0, 0);
+ cfq_schedule_dispatch(cfqd);
+ }
cfq_put_queue(cfqq);
}
hlist_add_head(&cfqq->cfq_hash, &cfqd->cfq_hash[hashval]);
atomic_set(&cfqq->ref, 0);
cfqq->cfqd = cfqd;
- /*
- * set ->slice_left to allow preemption for a new process
- */
- cfqq->slice_left = 2 * cfqd->cfq_slice_idle;
+
cfq_mark_cfqq_idle_window(cfqq);
cfq_mark_cfqq_prio_changed(cfqq);
cfq_mark_cfqq_queue_new(cfqq);
cfq_clear_cfqq_idle_window(cfqq);
}
-
/*
* Check if new_cfqq should preempt the currently active queue. Return 0 for
* no or if we aren't sure, a 1 will cause a preempt.
return 1;
if (!cfq_cfqq_wait_request(new_cfqq))
return 0;
- /*
- * if it doesn't have slice left, forget it
- */
- if (new_cfqq->slice_left < cfqd->cfq_slice_idle)
- return 0;
/*
* if the new request is sync, but the currently running queue is
* not, let the sync request have priority.
*/
static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
- cfq_slice_expired(cfqd, 1);
-
- if (!cfqq->slice_left)
- cfqq->slice_left = cfq_prio_to_slice(cfqd, cfqq) / 2;
+ cfq_slice_expired(cfqd, 1, 1);
/*
* Put the new queue at the front of the of the current list,
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);
}
/*
*/
if (cic == cfqd->active_cic &&
del_timer(&cfqd->idle_slice_timer)) {
- cfq_slice_expired(cfqd, 0);
+ cfq_slice_expired(cfqd, 0, 0);
blk_start_queueing(cfqd->queue);
}
return;
* 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))
- cfq_slice_expired(cfqd, 0);
+ 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, 1);
else if (sync && RB_EMPTY_ROOT(&cfqq->sort_list)) {
- if (!cfq_arm_slice_timer(cfqd, cfqq))
+ if (!cfq_arm_slice_timer(cfqd))
cfq_schedule_dispatch(cfqd);
}
}
struct cfq_data *cfqd = (struct cfq_data *) data;
struct cfq_queue *cfqq;
unsigned long flags;
+ int timed_out = 1;
spin_lock_irqsave(cfqd->queue->queue_lock, flags);
if ((cfqq = cfqd->active_queue) != NULL) {
- unsigned long now = jiffies;
+ timed_out = 0;
/*
* expired
*/
- if (time_after(now, cfqq->slice_end))
+ if (cfq_slice_used(cfqq))
goto expire;
/*
}
}
expire:
- cfq_slice_expired(cfqd, 0);
+ cfq_slice_expired(cfqd, 0, timed_out);
out_kick:
cfq_schedule_dispatch(cfqd);
out_cont:
spin_lock_irq(q->queue_lock);
if (cfqd->active_queue)
- __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
+ __cfq_slice_expired(cfqd, cfqd->active_queue, 0, 0);
while (!list_empty(&cfqd->cic_list)) {
struct cfq_io_context *cic = list_entry(cfqd->cic_list.next,
git.samba.org / sfrench / cifs-2.6.git / blobdiff