From e9ce335df51ff782035a15c261a3c0c9892a1767 Mon Sep 17 00:00:00 2001 From: Shaohua Li Date: Fri, 19 Mar 2010 08:03:04 +0100 Subject: cfq-iosched: fix a kbuild regression Alex Shi reported a kbuild regression which is about 10% performance lost. He bisected to this commit: 3dde36ddea3e07dd025c4c1ba47edec91606fec0. The reason is cfqq_close() can't find close cooperator. Restoring cfq_rq_close()'s threshold to original value makes the regression go away. Since for_preempt parameter isn't used anymore, this patch deletes it. Reported-by: Alex Shi Signed-off-by: Shaohua Li Acked-by: Corrado Zoccolo Signed-off-by: Jens Axboe --- block/cfq-iosched.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) (limited to 'block/cfq-iosched.c') diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index dee9d9378fee..8d5a2f2f7fb9 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -47,6 +47,7 @@ static const int cfq_hist_divisor = 4; #define CFQ_SERVICE_SHIFT 12 #define CFQQ_SEEK_THR (sector_t)(8 * 100) +#define CFQQ_CLOSE_THR (sector_t)(8 * 1024) #define CFQQ_SECT_THR_NONROT (sector_t)(2 * 32) #define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8) @@ -1660,9 +1661,9 @@ static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd, } static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq, - struct request *rq, bool for_preempt) + struct request *rq) { - return cfq_dist_from_last(cfqd, rq) <= CFQQ_SEEK_THR; + return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR; } static struct cfq_queue *cfqq_close(struct cfq_data *cfqd, @@ -1689,7 +1690,7 @@ static struct cfq_queue *cfqq_close(struct cfq_data *cfqd, * will contain the closest sector. */ __cfqq = rb_entry(parent, struct cfq_queue, p_node); - if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq, false)) + if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq)) return __cfqq; if (blk_rq_pos(__cfqq->next_rq) < sector) @@ -1700,7 +1701,7 @@ static struct cfq_queue *cfqq_close(struct cfq_data *cfqd, return NULL; __cfqq = rb_entry(node, struct cfq_queue, p_node); - if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq, false)) + if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq)) return __cfqq; return NULL; @@ -3103,7 +3104,7 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, * if this request is as-good as one we would expect from the * current cfqq, let it preempt */ - if (cfq_rq_close(cfqd, cfqq, rq, true)) + if (cfq_rq_close(cfqd, cfqq, rq)) return true; return false; -- cgit v1.2.3 From b1ffe737f5b743115ee46ffb59e338e580c54902 Mon Sep 17 00:00:00 2001 From: Divyesh Shah Date: Thu, 25 Mar 2010 15:45:03 +0100 Subject: cfq-iosched: Add additional blktrace log messages in CFQ for easier debugging These have helped us debug some issues we've noticed in earlier IO controller versions and should be useful now as well. The extra logging covers: - idling behavior. Since there are so many conditions based on which we decide to idle or not, this patch adds a log message for some conditions that we've found useful. - workload slices and current prio and workload type Changelog from v1: o moved log message from cfq_set_active_queue() to __cfq_set_active_queue() o changed queue_count to st->count Signed-off-by: Divyesh Shah Signed-off-by: Jens Axboe --- block/cfq-iosched.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) (limited to 'block/cfq-iosched.c') diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 8d5a2f2f7fb9..2f91c5351949 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -1518,7 +1518,8 @@ static void __cfq_set_active_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) { if (cfqq) { - cfq_log_cfqq(cfqd, cfqq, "set_active"); + cfq_log_cfqq(cfqd, cfqq, "set_active wl_prio:%d wl_type:%d", + cfqd->serving_prio, cfqd->serving_type); cfqq->slice_start = 0; cfqq->dispatch_start = jiffies; cfqq->allocated_slice = 0; @@ -1788,7 +1789,11 @@ static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq) * Otherwise, we do only if they are the last ones * in their service tree. */ - return service_tree->count == 1 && cfq_cfqq_sync(cfqq); + if (service_tree->count == 1 && cfq_cfqq_sync(cfqq)) + return 1; + cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d", + service_tree->count); + return 0; } static void cfq_arm_slice_timer(struct cfq_data *cfqd) @@ -1833,8 +1838,11 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd) * time slice. */ if (sample_valid(cic->ttime_samples) && - (cfqq->slice_end - jiffies < cic->ttime_mean)) + (cfqq->slice_end - jiffies < cic->ttime_mean)) { + cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%d", + cic->ttime_mean); return; + } cfq_mark_cfqq_wait_request(cfqq); @@ -2042,6 +2050,7 @@ static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg) slice = max(slice, 2 * cfqd->cfq_slice_idle); slice = max_t(unsigned, slice, CFQ_MIN_TT); + cfq_log(cfqd, "workload slice:%d", slice); cfqd->workload_expires = jiffies + slice; cfqd->noidle_tree_requires_idle = false; } @@ -3308,6 +3317,7 @@ static void cfq_completed_request(struct request_queue *q, struct request *rq) if (cfq_should_wait_busy(cfqd, cfqq)) { cfqq->slice_end = jiffies + cfqd->cfq_slice_idle; cfq_mark_cfqq_wait_busy(cfqq); + cfq_log_cfqq(cfqd, cfqq, "will busy wait"); } /* -- cgit v1.2.3 From 39c01b219fd30c74869b6fc8749f7900f04e9ef6 Mon Sep 17 00:00:00 2001 From: Divyesh Shah Date: Thu, 25 Mar 2010 15:45:57 +0100 Subject: cfq-iosched: Do not merge queues of BE and IDLE classes Even if they are found to be co-operating. The prio_trees do not have any IDLE cfqqs on them. cfq_close_cooperator() is called from cfq_select_queue() and cfq_completed_request(). The latter ensures that the close cooperator code does not get invoked if the current cfqq is of class IDLE but the former doesn't seem to have any such checks. So an IDLE cfqq may get merged with a BE cfqq from the same group which should be avoided. Signed-off-by: Divyesh Shah Acked-by: Vivek Goyal Signed-off-by: Jens Axboe --- block/cfq-iosched.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'block/cfq-iosched.c') diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 2f91c5351949..2c7a0f4f3cd7 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -1723,6 +1723,8 @@ static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd, { struct cfq_queue *cfqq; + if (cfq_class_idle(cur_cfqq)) + return NULL; if (!cfq_cfqq_sync(cur_cfqq)) return NULL; if (CFQQ_SEEKY(cur_cfqq)) -- cgit v1.2.3 From a74b2adae06265b8cfa335d7d40d4a5abd11e977 Mon Sep 17 00:00:00 2001 From: Ricky Benitez Date: Mon, 5 Apr 2010 18:22:17 +0200 Subject: block: expose the statistics in blkio.time and blkio.sectors for the root cgroup Currently, the io statistics for the root cgroup are maintained, but they are not shown because the device information is not available at the point that the root blkio cgroup is created. This patch updates the device information when the statistics are updated so that the statistics become visible. Signed-off-by: Ricky Benitez Acked-by: Vivek Goyal Signed-off-by: Jens Axboe --- block/cfq-iosched.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'block/cfq-iosched.c') diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 2c7a0f4f3cd7..7104ac816fb6 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -948,6 +948,11 @@ cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct cgroup *cgroup, int create) unsigned int major, minor; cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, key)); + if (cfqg && !cfqg->blkg.dev && bdi->dev && dev_name(bdi->dev)) { + sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor); + cfqg->blkg.dev = MKDEV(major, minor); + goto done; + } if (cfqg || !create) goto done; -- cgit v1.2.3 From 3440c49f5c5ecb4f29b0544aa87da71888404f8f Mon Sep 17 00:00:00 2001 From: Divyesh Shah Date: Fri, 9 Apr 2010 09:29:57 +0200 Subject: cfq-iosched: Fix the incorrect timeslice accounting with forced_dispatch When CFQ dispatches requests forcefully due to a barrier or changing iosched, it runs through all cfqq's dispatching requests and then expires each queue. However, it does not activate a cfqq before flushing its IOs resulting in using stale values for computing slice_used. This patch fixes it by calling activate queue before flushing reuqests from each queue. This is useful mostly for barrier requests because when the iosched is changing it really doesnt matter if we have incorrect accounting since we're going to break down all structures anyway. We also now expire the current timeslice before moving on with the dispatch to accurately account slice used for that cfqq. Signed-off-by: Divyesh Shah Signed-off-by: Jens Axboe --- block/cfq-iosched.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'block/cfq-iosched.c') diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 7104ac816fb6..b773000f8a06 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -2205,10 +2205,13 @@ static int cfq_forced_dispatch(struct cfq_data *cfqd) struct cfq_queue *cfqq; int dispatched = 0; - while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) + /* Expire the timeslice of the current active queue first */ + cfq_slice_expired(cfqd, 0); + while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) { + __cfq_set_active_queue(cfqd, cfqq); dispatched += __cfq_forced_dispatch_cfqq(cfqq); + } - cfq_slice_expired(cfqd, 0); BUG_ON(cfqd->busy_queues); cfq_log(cfqd, "forced_dispatch=%d", dispatched); -- cgit v1.2.3