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block: add sysfs file for controlling io stats accounting
This allows us to turn off disk stat accounting completely, for the cases where the 0.5-1% reduction in system time is important. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
Jens Axboe
parent
7598909e3e
commit
bc58ba9468
3 changed files with 88 additions and 36 deletions
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@ -64,11 +64,12 @@ static struct workqueue_struct *kblockd_workqueue;
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static void drive_stat_acct(struct request *rq, int new_io)
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{
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struct gendisk *disk = rq->rq_disk;
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struct hd_struct *part;
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int rw = rq_data_dir(rq);
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int cpu;
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if (!blk_fs_request(rq) || !rq->rq_disk)
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if (!blk_fs_request(rq) || !disk || !blk_queue_io_stat(disk->queue))
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return;
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cpu = part_stat_lock();
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@ -599,8 +600,7 @@ blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id)
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q->request_fn = rfn;
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q->prep_rq_fn = NULL;
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q->unplug_fn = generic_unplug_device;
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q->queue_flags = (1 << QUEUE_FLAG_CLUSTER |
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1 << QUEUE_FLAG_STACKABLE);
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q->queue_flags = QUEUE_FLAG_DEFAULT;
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q->queue_lock = lock;
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blk_queue_segment_boundary(q, BLK_SEG_BOUNDARY_MASK);
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@ -1663,6 +1663,55 @@ void blkdev_dequeue_request(struct request *req)
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}
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EXPORT_SYMBOL(blkdev_dequeue_request);
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static void blk_account_io_completion(struct request *req, unsigned int bytes)
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{
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struct gendisk *disk = req->rq_disk;
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if (!disk || !blk_queue_io_stat(disk->queue))
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return;
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if (blk_fs_request(req)) {
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const int rw = rq_data_dir(req);
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struct hd_struct *part;
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int cpu;
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cpu = part_stat_lock();
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part = disk_map_sector_rcu(req->rq_disk, req->sector);
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part_stat_add(cpu, part, sectors[rw], bytes >> 9);
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part_stat_unlock();
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}
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}
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static void blk_account_io_done(struct request *req)
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{
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struct gendisk *disk = req->rq_disk;
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if (!disk || !blk_queue_io_stat(disk->queue))
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return;
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/*
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* Account IO completion. bar_rq isn't accounted as a normal
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* IO on queueing nor completion. Accounting the containing
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* request is enough.
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*/
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if (blk_fs_request(req) && req != &req->q->bar_rq) {
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unsigned long duration = jiffies - req->start_time;
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const int rw = rq_data_dir(req);
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struct hd_struct *part;
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int cpu;
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cpu = part_stat_lock();
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part = disk_map_sector_rcu(disk, req->sector);
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part_stat_inc(cpu, part, ios[rw]);
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part_stat_add(cpu, part, ticks[rw], duration);
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part_round_stats(cpu, part);
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part_dec_in_flight(part);
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part_stat_unlock();
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}
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}
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/**
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* __end_that_request_first - end I/O on a request
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* @req: the request being processed
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@ -1698,16 +1747,7 @@ static int __end_that_request_first(struct request *req, int error,
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(unsigned long long)req->sector);
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}
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if (blk_fs_request(req) && req->rq_disk) {
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const int rw = rq_data_dir(req);
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struct hd_struct *part;
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int cpu;
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cpu = part_stat_lock();
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part = disk_map_sector_rcu(req->rq_disk, req->sector);
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part_stat_add(cpu, part, sectors[rw], nr_bytes >> 9);
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part_stat_unlock();
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}
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blk_account_io_completion(req, nr_bytes);
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total_bytes = bio_nbytes = 0;
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while ((bio = req->bio) != NULL) {
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@ -1787,8 +1827,6 @@ static int __end_that_request_first(struct request *req, int error,
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*/
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static void end_that_request_last(struct request *req, int error)
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{
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struct gendisk *disk = req->rq_disk;
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if (blk_rq_tagged(req))
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blk_queue_end_tag(req->q, req);
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@ -1800,27 +1838,7 @@ static void end_that_request_last(struct request *req, int error)
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blk_delete_timer(req);
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/*
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* Account IO completion. bar_rq isn't accounted as a normal
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* IO on queueing nor completion. Accounting the containing
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* request is enough.
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*/
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if (disk && blk_fs_request(req) && req != &req->q->bar_rq) {
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unsigned long duration = jiffies - req->start_time;
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const int rw = rq_data_dir(req);
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struct hd_struct *part;
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int cpu;
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cpu = part_stat_lock();
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part = disk_map_sector_rcu(disk, req->sector);
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part_stat_inc(cpu, part, ios[rw]);
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part_stat_add(cpu, part, ticks[rw], duration);
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part_round_stats(cpu, part);
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part_dec_in_flight(part);
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part_stat_unlock();
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}
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blk_account_io_done(req);
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if (req->end_io)
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req->end_io(req, error);
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@ -197,6 +197,27 @@ queue_rq_affinity_store(struct request_queue *q, const char *page, size_t count)
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return ret;
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}
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static ssize_t queue_iostats_show(struct request_queue *q, char *page)
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{
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return queue_var_show(blk_queue_io_stat(q), page);
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}
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static ssize_t queue_iostats_store(struct request_queue *q, const char *page,
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size_t count)
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{
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unsigned long stats;
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ssize_t ret = queue_var_store(&stats, page, count);
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spin_lock_irq(q->queue_lock);
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if (stats)
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queue_flag_set(QUEUE_FLAG_IO_STAT, q);
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else
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queue_flag_clear(QUEUE_FLAG_IO_STAT, q);
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spin_unlock_irq(q->queue_lock);
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return ret;
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}
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static struct queue_sysfs_entry queue_requests_entry = {
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.attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR },
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.show = queue_requests_show,
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@ -249,6 +270,12 @@ static struct queue_sysfs_entry queue_rq_affinity_entry = {
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.store = queue_rq_affinity_store,
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};
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static struct queue_sysfs_entry queue_iostats_entry = {
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.attr = {.name = "iostats", .mode = S_IRUGO | S_IWUSR },
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.show = queue_iostats_show,
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.store = queue_iostats_store,
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};
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static struct attribute *default_attrs[] = {
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&queue_requests_entry.attr,
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&queue_ra_entry.attr,
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@ -259,6 +286,7 @@ static struct attribute *default_attrs[] = {
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&queue_nonrot_entry.attr,
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&queue_nomerges_entry.attr,
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&queue_rq_affinity_entry.attr,
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&queue_iostats_entry.attr,
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NULL,
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};
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@ -451,6 +451,11 @@ struct request_queue
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#define QUEUE_FLAG_STACKABLE 13 /* supports request stacking */
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#define QUEUE_FLAG_NONROT 14 /* non-rotational device (SSD) */
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#define QUEUE_FLAG_VIRT QUEUE_FLAG_NONROT /* paravirt device */
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#define QUEUE_FLAG_IO_STAT 15 /* do IO stats */
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#define QUEUE_FLAG_DEFAULT ((1 << QUEUE_FLAG_IO_STAT) | \
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(1 << QUEUE_FLAG_CLUSTER) | \
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1 << QUEUE_FLAG_STACKABLE)
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static inline int queue_is_locked(struct request_queue *q)
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{
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@ -567,6 +572,7 @@ enum {
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#define blk_queue_stopped(q) test_bit(QUEUE_FLAG_STOPPED, &(q)->queue_flags)
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#define blk_queue_nomerges(q) test_bit(QUEUE_FLAG_NOMERGES, &(q)->queue_flags)
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#define blk_queue_nonrot(q) test_bit(QUEUE_FLAG_NONROT, &(q)->queue_flags)
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#define blk_queue_io_stat(q) test_bit(QUEUE_FLAG_IO_STAT, &(q)->queue_flags)
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#define blk_queue_flushing(q) ((q)->ordseq)
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#define blk_queue_stackable(q) \
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test_bit(QUEUE_FLAG_STACKABLE, &(q)->queue_flags)
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