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authorLinus Torvalds <torvalds@linux-foundation.org>2009-04-07 11:06:41 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-04-07 11:06:41 -0700
commit6a5d263866d699ebf6843105497afc86ee53de5b (patch)
tree439195e272631908cdc2e3e44abaf7e1c3447157 /block
parentaeeae86859f4319de0a4946b44771d9926eeed54 (diff)
parentffcd7dca3ab78f9f425971756e5e90024157f6be (diff)
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Merge branch 'for-linus' of git://git.kernel.dk/linux-2.6-block
* 'for-linus' of git://git.kernel.dk/linux-2.6-block: loop: mutex already unlocked in loop_clr_fd() cfq-iosched: don't let idling interfere with plugging block: remove unused REQ_UNPLUG cfq-iosched: kill two unused cfqq flags cfq-iosched: change dispatch logic to deal with single requests at the time mflash: initial support cciss: change to discover first memory BAR cciss: kernel scan thread for MSA2012 cciss: fix residual count for block pc requests block: fix inconsistency in I/O stat accounting code block: elevator quiescing helpers
Diffstat (limited to 'block')
-rw-r--r--block/blk-core.c15
-rw-r--r--block/blk-merge.c29
-rw-r--r--block/blk-sysfs.c4
-rw-r--r--block/blk.h14
-rw-r--r--block/cfq-iosched.c202
-rw-r--r--block/elevator.c42
6 files changed, 169 insertions, 137 deletions
diff --git a/block/blk-core.c b/block/blk-core.c
index 25572802dac..43fdedc524e 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -64,12 +64,11 @@ static struct workqueue_struct *kblockd_workqueue;
static void drive_stat_acct(struct request *rq, int new_io)
{
- struct gendisk *disk = rq->rq_disk;
struct hd_struct *part;
int rw = rq_data_dir(rq);
int cpu;
- if (!blk_fs_request(rq) || !disk || !blk_do_io_stat(disk->queue))
+ if (!blk_fs_request(rq) || !blk_do_io_stat(rq))
return;
cpu = part_stat_lock();
@@ -1124,8 +1123,6 @@ void init_request_from_bio(struct request *req, struct bio *bio)
if (bio_sync(bio))
req->cmd_flags |= REQ_RW_SYNC;
- if (bio_unplug(bio))
- req->cmd_flags |= REQ_UNPLUG;
if (bio_rw_meta(bio))
req->cmd_flags |= REQ_RW_META;
if (bio_noidle(bio))
@@ -1675,9 +1672,7 @@ EXPORT_SYMBOL(blkdev_dequeue_request);
static void blk_account_io_completion(struct request *req, unsigned int bytes)
{
- struct gendisk *disk = req->rq_disk;
-
- if (!disk || !blk_do_io_stat(disk->queue))
+ if (!blk_do_io_stat(req))
return;
if (blk_fs_request(req)) {
@@ -1694,9 +1689,7 @@ static void blk_account_io_completion(struct request *req, unsigned int bytes)
static void blk_account_io_done(struct request *req)
{
- struct gendisk *disk = req->rq_disk;
-
- if (!disk || !blk_do_io_stat(disk->queue))
+ if (!blk_do_io_stat(req))
return;
/*
@@ -1711,7 +1704,7 @@ static void blk_account_io_done(struct request *req)
int cpu;
cpu = part_stat_lock();
- part = disk_map_sector_rcu(disk, req->sector);
+ part = disk_map_sector_rcu(req->rq_disk, req->sector);
part_stat_inc(cpu, part, ios[rw]);
part_stat_add(cpu, part, ticks[rw], duration);
diff --git a/block/blk-merge.c b/block/blk-merge.c
index e39cb24b767..63760ca3da0 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -338,6 +338,22 @@ static int ll_merge_requests_fn(struct request_queue *q, struct request *req,
return 1;
}
+static void blk_account_io_merge(struct request *req)
+{
+ if (blk_do_io_stat(req)) {
+ struct hd_struct *part;
+ int cpu;
+
+ cpu = part_stat_lock();
+ part = disk_map_sector_rcu(req->rq_disk, req->sector);
+
+ part_round_stats(cpu, part);
+ part_dec_in_flight(part);
+
+ part_stat_unlock();
+ }
+}
+
/*
* Has to be called with the request spinlock acquired
*/
@@ -386,18 +402,7 @@ static int attempt_merge(struct request_queue *q, struct request *req,
elv_merge_requests(q, req, next);
- if (req->rq_disk) {
- struct hd_struct *part;
- int cpu;
-
- cpu = part_stat_lock();
- part = disk_map_sector_rcu(req->rq_disk, req->sector);
-
- part_round_stats(cpu, part);
- part_dec_in_flight(part);
-
- part_stat_unlock();
- }
+ blk_account_io_merge(req);
req->ioprio = ioprio_best(req->ioprio, next->ioprio);
if (blk_rq_cpu_valid(next))
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 3ff9bba3379..73f36beff5c 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -209,10 +209,14 @@ static ssize_t queue_iostats_store(struct request_queue *q, const char *page,
ssize_t ret = queue_var_store(&stats, page, count);
spin_lock_irq(q->queue_lock);
+ elv_quisce_start(q);
+
if (stats)
queue_flag_set(QUEUE_FLAG_IO_STAT, q);
else
queue_flag_clear(QUEUE_FLAG_IO_STAT, q);
+
+ elv_quisce_end(q);
spin_unlock_irq(q->queue_lock);
return ret;
diff --git a/block/blk.h b/block/blk.h
index 3ee94358b43..24fcaeeaf62 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -70,6 +70,10 @@ void blk_queue_congestion_threshold(struct request_queue *q);
int blk_dev_init(void);
+void elv_quisce_start(struct request_queue *q);
+void elv_quisce_end(struct request_queue *q);
+
+
/*
* Return the threshold (number of used requests) at which the queue is
* considered to be congested. It include a little hysteresis to keep the
@@ -108,12 +112,14 @@ static inline int blk_cpu_to_group(int cpu)
#endif
}
-static inline int blk_do_io_stat(struct request_queue *q)
+static inline int blk_do_io_stat(struct request *rq)
{
- if (q)
- return blk_queue_io_stat(q);
+ struct gendisk *disk = rq->rq_disk;
- return 0;
+ if (!disk || !disk->queue)
+ return 0;
+
+ return blk_queue_io_stat(disk->queue) && (rq->cmd_flags & REQ_ELVPRIV);
}
#endif
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 9e809345f71..a4809de6fea 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -160,6 +160,7 @@ struct cfq_queue {
unsigned long slice_end;
long slice_resid;
+ unsigned int slice_dispatch;
/* pending metadata requests */
int meta_pending;
@@ -176,13 +177,12 @@ struct cfq_queue {
enum cfqq_state_flags {
CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
+ CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */
CFQ_CFQQ_FLAG_must_alloc, /* must be allowed rq alloc */
CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
- CFQ_CFQQ_FLAG_must_dispatch, /* must dispatch, even if expired */
CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
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 */
CFQ_CFQQ_FLAG_sync, /* synchronous queue */
};
@@ -203,13 +203,12 @@ static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
CFQ_CFQQ_FNS(on_rr);
CFQ_CFQQ_FNS(wait_request);
+CFQ_CFQQ_FNS(must_dispatch);
CFQ_CFQQ_FNS(must_alloc);
CFQ_CFQQ_FNS(must_alloc_slice);
-CFQ_CFQQ_FNS(must_dispatch);
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);
CFQ_CFQQ_FNS(sync);
#undef CFQ_CFQQ_FNS
@@ -774,10 +773,15 @@ static void __cfq_set_active_queue(struct cfq_data *cfqd,
if (cfqq) {
cfq_log_cfqq(cfqd, cfqq, "set_active");
cfqq->slice_end = 0;
+ cfqq->slice_dispatch = 0;
+
+ cfq_clear_cfqq_wait_request(cfqq);
+ cfq_clear_cfqq_must_dispatch(cfqq);
cfq_clear_cfqq_must_alloc_slice(cfqq);
cfq_clear_cfqq_fifo_expire(cfqq);
cfq_mark_cfqq_slice_new(cfqq);
- cfq_clear_cfqq_queue_new(cfqq);
+
+ del_timer(&cfqd->idle_slice_timer);
}
cfqd->active_queue = cfqq;
@@ -795,7 +799,6 @@ __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
if (cfq_cfqq_wait_request(cfqq))
del_timer(&cfqd->idle_slice_timer);
- cfq_clear_cfqq_must_dispatch(cfqq);
cfq_clear_cfqq_wait_request(cfqq);
/*
@@ -924,7 +927,6 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd)
(sample_valid(cic->ttime_samples) && cic->ttime_mean > 2))
return;
- cfq_mark_cfqq_must_dispatch(cfqq);
cfq_mark_cfqq_wait_request(cfqq);
/*
@@ -1010,7 +1012,7 @@ static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
/*
* The active queue has run out of time, expire it and select new.
*/
- if (cfq_slice_used(cfqq))
+ if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq))
goto expire;
/*
@@ -1053,66 +1055,6 @@ keep_queue:
return cfqq;
}
-/*
- * Dispatch some requests from cfqq, moving them to the request queue
- * dispatch list.
- */
-static int
-__cfq_dispatch_requests(struct cfq_data *cfqd, struct cfq_queue *cfqq,
- int max_dispatch)
-{
- int dispatched = 0;
-
- BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
-
- do {
- struct request *rq;
-
- /*
- * follow expired path, else get first next available
- */
- rq = cfq_check_fifo(cfqq);
- if (rq == NULL)
- rq = cfqq->next_rq;
-
- /*
- * finally, insert request into driver dispatch list
- */
- cfq_dispatch_insert(cfqd->queue, rq);
-
- dispatched++;
-
- if (!cfqd->active_cic) {
- atomic_inc(&RQ_CIC(rq)->ioc->refcount);
- cfqd->active_cic = RQ_CIC(rq);
- }
-
- if (RB_EMPTY_ROOT(&cfqq->sort_list))
- break;
-
- /*
- * If there is a non-empty RT cfqq waiting for current
- * cfqq's timeslice to complete, pre-empt this cfqq
- */
- if (!cfq_class_rt(cfqq) && cfqd->busy_rt_queues)
- break;
-
- } while (dispatched < max_dispatch);
-
- /*
- * expire an async queue immediately if it has used up its slice. idle
- * queue always expire after 1 dispatch round.
- */
- if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
- dispatched >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
- cfq_class_idle(cfqq))) {
- cfqq->slice_end = jiffies + 1;
- cfq_slice_expired(cfqd, 0);
- }
-
- return dispatched;
-}
-
static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
{
int dispatched = 0;
@@ -1146,11 +1088,45 @@ 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)
+{
+ 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_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;
- int dispatched;
+ unsigned int max_dispatch;
if (!cfqd->busy_queues)
return 0;
@@ -1158,29 +1134,63 @@ static int cfq_dispatch_requests(struct request_queue *q, int force)
if (unlikely(force))
return cfq_forced_dispatch(cfqd);
- dispatched = 0;
- while ((cfqq = cfq_select_queue(cfqd)) != NULL) {
- int max_dispatch;
+ cfqq = cfq_select_queue(cfqd);
+ if (!cfqq)
+ return 0;
+
+ /*
+ * 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;
+
+ max_dispatch = cfqd->cfq_quantum;
+ if (cfq_class_idle(cfqq))
+ max_dispatch = 1;
- max_dispatch = cfqd->cfq_quantum;
+ /*
+ * Does this cfqq already have too much IO in flight?
+ */
+ if (cfqq->dispatched >= max_dispatch) {
+ /*
+ * idle queue must always only have a single IO in flight
+ */
if (cfq_class_idle(cfqq))
- max_dispatch = 1;
+ return 0;
- if (cfqq->dispatched >= max_dispatch && cfqd->busy_queues > 1)
- break;
+ /*
+ * We have other queues, don't allow more IO from this one
+ */
+ if (cfqd->busy_queues > 1)
+ return 0;
- if (cfqd->sync_flight && !cfq_cfqq_sync(cfqq))
- break;
+ /*
+ * we are the only queue, allow up to 4 times of 'quantum'
+ */
+ if (cfqq->dispatched >= 4 * max_dispatch)
+ return 0;
+ }
- cfq_clear_cfqq_must_dispatch(cfqq);
- cfq_clear_cfqq_wait_request(cfqq);
- del_timer(&cfqd->idle_slice_timer);
+ /*
+ * Dispatch a request from this cfqq
+ */
+ cfq_dispatch_request(cfqd, cfqq);
+ cfqq->slice_dispatch++;
+ cfq_clear_cfqq_must_dispatch(cfqq);
- dispatched += __cfq_dispatch_requests(cfqd, cfqq, max_dispatch);
+ /*
+ * expire an async queue immediately if it has used up its slice. idle
+ * queue always expire after 1 dispatch round.
+ */
+ if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
+ cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
+ cfq_class_idle(cfqq))) {
+ cfqq->slice_end = jiffies + 1;
+ cfq_slice_expired(cfqd, 0);
}
- cfq_log(cfqd, "dispatched=%d", dispatched);
- return dispatched;
+ cfq_log(cfqd, "dispatched a request");
+ return 1;
}
/*
@@ -1506,7 +1516,6 @@ retry:
cfqq->cfqd = cfqd;
cfq_mark_cfqq_prio_changed(cfqq);
- cfq_mark_cfqq_queue_new(cfqq);
cfq_init_prio_data(cfqq, ioc);
@@ -1893,15 +1902,13 @@ cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
if (cfqq == cfqd->active_queue) {
/*
- * if we are waiting for a request for this queue, let it rip
- * immediately and flag that we must not expire this queue
- * just now
+ * Remember that we saw a request from this process, but
+ * don't start queuing just yet. Otherwise we risk seeing lots
+ * of tiny requests, because we disrupt the normal plugging
+ * and merging.
*/
- if (cfq_cfqq_wait_request(cfqq)) {
+ if (cfq_cfqq_wait_request(cfqq))
cfq_mark_cfqq_must_dispatch(cfqq);
- del_timer(&cfqd->idle_slice_timer);
- blk_start_queueing(cfqd->queue);
- }
} else if (cfq_should_preempt(cfqd, cfqq, rq)) {
/*
* not the active queue - expire current slice if it is
@@ -1910,7 +1917,6 @@ cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
* this new queue is RT and the current one is BE
*/
cfq_preempt_queue(cfqd, cfqq);
- cfq_mark_cfqq_must_dispatch(cfqq);
blk_start_queueing(cfqd->queue);
}
}
@@ -2172,6 +2178,12 @@ static void cfq_idle_slice_timer(unsigned long data)
timed_out = 0;
/*
+ * We saw a request before the queue expired, let it through
+ */
+ if (cfq_cfqq_must_dispatch(cfqq))
+ goto out_kick;
+
+ /*
* expired
*/
if (cfq_slice_used(cfqq))
@@ -2187,10 +2199,8 @@ static void cfq_idle_slice_timer(unsigned long data)
/*
* not expired and it has a request pending, let it dispatch
*/
- if (!RB_EMPTY_ROOT(&cfqq->sort_list)) {
- cfq_mark_cfqq_must_dispatch(cfqq);
+ if (!RB_EMPTY_ROOT(&cfqq->sort_list))
goto out_kick;
- }
}
expire:
cfq_slice_expired(cfqd, timed_out);
diff --git a/block/elevator.c b/block/elevator.c
index ca6788a0195..fb81bcc14a8 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -573,7 +573,7 @@ void elv_requeue_request(struct request_queue *q, struct request *rq)
elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE);
}
-static void elv_drain_elevator(struct request_queue *q)
+void elv_drain_elevator(struct request_queue *q)
{
static int printed;
while (q->elevator->ops->elevator_dispatch_fn(q, 1))
@@ -587,6 +587,31 @@ static void elv_drain_elevator(struct request_queue *q)
}
}
+/*
+ * Call with queue lock held, interrupts disabled
+ */
+void elv_quisce_start(struct request_queue *q)
+{
+ queue_flag_set(QUEUE_FLAG_ELVSWITCH, q);
+
+ /*
+ * make sure we don't have any requests in flight
+ */
+ elv_drain_elevator(q);
+ while (q->rq.elvpriv) {
+ blk_start_queueing(q);
+ spin_unlock_irq(q->queue_lock);
+ msleep(10);
+ spin_lock_irq(q->queue_lock);
+ elv_drain_elevator(q);
+ }
+}
+
+void elv_quisce_end(struct request_queue *q)
+{
+ queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q);
+}
+
void elv_insert(struct request_queue *q, struct request *rq, int where)
{
struct list_head *pos;
@@ -1101,18 +1126,7 @@ static int elevator_switch(struct request_queue *q, struct elevator_type *new_e)
* Turn on BYPASS and drain all requests w/ elevator private data
*/
spin_lock_irq(q->queue_lock);
-
- queue_flag_set(QUEUE_FLAG_ELVSWITCH, q);
-
- elv_drain_elevator(q);
-
- while (q->rq.elvpriv) {
- blk_start_queueing(q);
- spin_unlock_irq(q->queue_lock);
- msleep(10);
- spin_lock_irq(q->queue_lock);
- elv_drain_elevator(q);
- }
+ elv_quisce_start(q);
/*
* Remember old elevator.
@@ -1136,7 +1150,7 @@ static int elevator_switch(struct request_queue *q, struct elevator_type *new_e)
*/
elevator_exit(old_elevator);
spin_lock_irq(q->queue_lock);
- queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q);
+ elv_quisce_end(q);
spin_unlock_irq(q->queue_lock);
blk_add_trace_msg(q, "elv switch: %s", e->elevator_type->elevator_name);