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Commit 316d315b authored by Nikanth Karthikesan's avatar Nikanth Karthikesan Committed by Jens Axboe
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block: Seperate read and write statistics of in_flight requests v2 



Commit a9327cac added seperate read
and write statistics of in_flight requests. And exported the number
of read and write requests in progress seperately through sysfs.

But  Corrado Zoccolo <czoccolo@gmail.com> reported getting strange
output from "iostat -kx 2". Global values for service time and
utilization were garbage. For interval values, utilization was always
100%, and service time is higher than normal.

So this was reverted by commit 0f78ab98

The problem was in part_round_stats_single(), I missed the following:
        if (now == part->stamp)
                return;

-       if (part->in_flight) {
+       if (part_in_flight(part)) {
                __part_stat_add(cpu, part, time_in_queue,
                                part_in_flight(part) * (now - part->stamp));
                __part_stat_add(cpu, part, io_ticks, (now - part->stamp));

With this chunk included, the reported regression gets fixed.

Signed-off-by: default avatarNikanth Karthikesan <knikanth@suse.de>

--
Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent 23e018a1

block/blk-core.c

+4 −4
Original line number Diff line number Diff line
@@ -70,7 +70,7 @@ static void drive_stat_acct(struct request *rq, int new_io) 
		part_stat_inc(cpu, part, merges[rw]);

	else {

		part_round_stats(cpu, part);

		part_inc_in_flight(part);

		part_inc_in_flight(part, rw);

	}



	part_stat_unlock();
@@ -1030,9 +1030,9 @@ static void part_round_stats_single(int cpu, struct hd_struct *part, 
	if (now == part->stamp)

		return;



	if (part->in_flight) {

	if (part_in_flight(part)) {

		__part_stat_add(cpu, part, time_in_queue,

				part->in_flight * (now - part->stamp));

				part_in_flight(part) * (now - part->stamp));

		__part_stat_add(cpu, part, io_ticks, (now - part->stamp));

	}

	part->stamp = now;
@@ -1739,7 +1739,7 @@ static void blk_account_io_done(struct request *req) 
		part_stat_inc(cpu, part, ios[rw]);

		part_stat_add(cpu, part, ticks[rw], duration);

		part_round_stats(cpu, part);

		part_dec_in_flight(part);

		part_dec_in_flight(part, rw);



		part_stat_unlock();

	}

block/blk-merge.c

+1 −1
Original line number Diff line number Diff line
@@ -351,7 +351,7 @@ static void blk_account_io_merge(struct request *req) 
		part = disk_map_sector_rcu(req->rq_disk, blk_rq_pos(req));



		part_round_stats(cpu, part);

		part_dec_in_flight(part);

		part_dec_in_flight(part, rq_data_dir(req));



		part_stat_unlock();

	}

block/genhd.c

+3 −1
Original line number Diff line number Diff line
@@ -869,6 +869,7 @@ static DEVICE_ATTR(size, S_IRUGO, part_size_show, NULL); 
static DEVICE_ATTR(alignment_offset, S_IRUGO, disk_alignment_offset_show, NULL);

static DEVICE_ATTR(capability, S_IRUGO, disk_capability_show, NULL);

static DEVICE_ATTR(stat, S_IRUGO, part_stat_show, NULL);

static DEVICE_ATTR(inflight, S_IRUGO, part_inflight_show, NULL);

#ifdef CONFIG_FAIL_MAKE_REQUEST

static struct device_attribute dev_attr_fail =

	__ATTR(make-it-fail, S_IRUGO|S_IWUSR, part_fail_show, part_fail_store);
@@ -888,6 +889,7 @@ static struct attribute *disk_attrs[] = { 
	&dev_attr_alignment_offset.attr,

	&dev_attr_capability.attr,

	&dev_attr_stat.attr,

	&dev_attr_inflight.attr,

#ifdef CONFIG_FAIL_MAKE_REQUEST

	&dev_attr_fail.attr,

#endif
@@ -1053,7 +1055,7 @@ static int diskstats_show(struct seq_file *seqf, void *v) 
			   part_stat_read(hd, merges[1]),

			   (unsigned long long)part_stat_read(hd, sectors[1]),

			   jiffies_to_msecs(part_stat_read(hd, ticks[1])),

			   hd->in_flight,

			   part_in_flight(hd),

			   jiffies_to_msecs(part_stat_read(hd, io_ticks)),

			   jiffies_to_msecs(part_stat_read(hd, time_in_queue))

			);

drivers/md/dm.c

+10 −6
Original line number Diff line number Diff line
@@ -130,7 +130,7 @@ struct mapped_device { 
	/*

	 * A list of ios that arrived while we were suspended.

	 */

	atomic_t pending;

	atomic_t pending[2];

	wait_queue_head_t wait;

	struct work_struct work;

	struct bio_list deferred;
@@ -453,13 +453,14 @@ static void start_io_acct(struct dm_io *io) 
{

	struct mapped_device *md = io->md;

	int cpu;

	int rw = bio_data_dir(io->bio);



	io->start_time = jiffies;



	cpu = part_stat_lock();

	part_round_stats(cpu, &dm_disk(md)->part0);

	part_stat_unlock();

	dm_disk(md)->part0.in_flight = atomic_inc_return(&md->pending);

	dm_disk(md)->part0.in_flight[rw] = atomic_inc_return(&md->pending[rw]);

}



static void end_io_acct(struct dm_io *io)
@@ -479,8 +480,9 @@ static void end_io_acct(struct dm_io *io) 
	 * After this is decremented the bio must not be touched if it is

	 * a barrier.

	 */

	dm_disk(md)->part0.in_flight = pending =

		atomic_dec_return(&md->pending);

	dm_disk(md)->part0.in_flight[rw] = pending =

		atomic_dec_return(&md->pending[rw]);

	pending += atomic_read(&md->pending[rw^0x1]);



	/* nudge anyone waiting on suspend queue */

	if (!pending)
@@ -1785,7 +1787,8 @@ static struct mapped_device *alloc_dev(int minor) 
	if (!md->disk)

		goto bad_disk;



	atomic_set(&md->pending, 0);

	atomic_set(&md->pending[0], 0);

	atomic_set(&md->pending[1], 0);

	init_waitqueue_head(&md->wait);

	INIT_WORK(&md->work, dm_wq_work);

	init_waitqueue_head(&md->eventq);
@@ -2088,7 +2091,8 @@ static int dm_wait_for_completion(struct mapped_device *md, int interruptible) 
				break;

			}

			spin_unlock_irqrestore(q->queue_lock, flags);

		} else if (!atomic_read(&md->pending))

		} else if (!atomic_read(&md->pending[0]) &&

					!atomic_read(&md->pending[1]))

			break;



		if (interruptible == TASK_INTERRUPTIBLE &&

fs/partitions/check.c

+11 −1
Original line number Diff line number Diff line
@@ -248,11 +248,19 @@ ssize_t part_stat_show(struct device *dev, 
		part_stat_read(p, merges[WRITE]),

		(unsigned long long)part_stat_read(p, sectors[WRITE]),

		jiffies_to_msecs(part_stat_read(p, ticks[WRITE])),

		p->in_flight,

		part_in_flight(p),

		jiffies_to_msecs(part_stat_read(p, io_ticks)),

		jiffies_to_msecs(part_stat_read(p, time_in_queue)));

}



ssize_t part_inflight_show(struct device *dev,

			struct device_attribute *attr, char *buf)

{

	struct hd_struct *p = dev_to_part(dev);



	return sprintf(buf, "%8u %8u\n", p->in_flight[0], p->in_flight[1]);

}



#ifdef CONFIG_FAIL_MAKE_REQUEST

ssize_t part_fail_show(struct device *dev,

		       struct device_attribute *attr, char *buf)
@@ -281,6 +289,7 @@ static DEVICE_ATTR(start, S_IRUGO, part_start_show, NULL); 
static DEVICE_ATTR(size, S_IRUGO, part_size_show, NULL);

static DEVICE_ATTR(alignment_offset, S_IRUGO, part_alignment_offset_show, NULL);

static DEVICE_ATTR(stat, S_IRUGO, part_stat_show, NULL);

static DEVICE_ATTR(inflight, S_IRUGO, part_inflight_show, NULL);

#ifdef CONFIG_FAIL_MAKE_REQUEST

static struct device_attribute dev_attr_fail =

	__ATTR(make-it-fail, S_IRUGO|S_IWUSR, part_fail_show, part_fail_store);
@@ -292,6 +301,7 @@ static struct attribute *part_attrs[] = { 
	&dev_attr_size.attr,

	&dev_attr_alignment_offset.attr,

	&dev_attr_stat.attr,

	&dev_attr_inflight.attr,

#ifdef CONFIG_FAIL_MAKE_REQUEST

	&dev_attr_fail.attr,

#endif