[PATCH] device-mapper disk statistics: timing

Record I/O timing statistics The start time is added to struct dm_io, an existing structure allocated privately internally within dm and attached to each incoming bio. We export disk_round_stats() from block/ll_rw_blk.c instead of creating a private clone. Signed-off-by: Jun'ichi "Nick" Nomura <j-nomura@ce.jp.nec.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] device-mapper disk statistics: timing
Record I/O timing statistics The start time is added to struct dm_io, an existing structure allocated privately internally within dm and attached to each incoming bio. We export disk_round_stats() from block/ll_rw_blk.c instead of creating a private clone. Signed-off-by: Jun'ichi "Nick" Nomura <j-nomura@ce.jp.nec.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Jun'ichi "Nick" Nomura · Linus Torvalds
1 parent 12f03a49cf
Showing 2 changed files with 35 additions and 2 deletions Side-by-side Diff
block/ll_rw_blk.c
drivers/md/dm.c
@@ -2579,6 +2579,8 @@
 	disk->stamp = now;
 }
  
+EXPORT_SYMBOL_GPL(disk_round_stats);
+
 /*
  * queue lock must be held
  */
@@ -31,6 +31,7 @@
 	int error;
 	struct bio *bio;
 	atomic_t io_count;
+	unsigned long start_time;
 };
  
 /*
@@ -244,6 +245,36 @@
 	mempool_free(tio, md->tio_pool);
 }
  
+static void start_io_acct(struct dm_io *io)
+{
+	struct mapped_device *md = io->md;
+
+	io->start_time = jiffies;
+
+	preempt_disable();
+	disk_round_stats(dm_disk(md));
+	preempt_enable();
+	dm_disk(md)->in_flight = atomic_inc_return(&md->pending);
+}
+
+static int end_io_acct(struct dm_io *io)
+{
+	struct mapped_device *md = io->md;
+	struct bio *bio = io->bio;
+	unsigned long duration = jiffies - io->start_time;
+	int pending;
+	int rw = bio_data_dir(bio);
+
+	preempt_disable();
+	disk_round_stats(dm_disk(md));
+	preempt_enable();
+	dm_disk(md)->in_flight = pending = atomic_dec_return(&md->pending);
+
+	disk_stat_add(dm_disk(md), ticks[rw], duration);
+
+	return !pending;
+}
+
 /*
  * Add the bio to the list of deferred io.
  */
@@ -299,7 +330,7 @@
 		io->error = error;
  
 	if (atomic_dec_and_test(&io->io_count)) {
-		if (atomic_dec_and_test(&io->md->pending))
+		if (end_io_acct(io))
 			/* nudge anyone waiting on suspend queue */
 			wake_up(&io->md->wait);
  
@@ -554,7 +585,7 @@
 	ci.sector_count = bio_sectors(bio);
 	ci.idx = bio->bi_idx;
  
-	atomic_inc(&md->pending);
+	start_io_acct(ci.io);
 	while (ci.sector_count)
 		__clone_and_map(&ci);
...	...	@@ -2579,6 +2579,8 @@
2579	2579	disk->stamp = now;
2580	2580	}
2581	2581
	2582	+EXPORT_SYMBOL_GPL(disk_round_stats);
	2583	+
2582	2584	/*
2583	2585	* queue lock must be held
2584	2586	*/
...	...	@@ -31,6 +31,7 @@
31	31	int error;
32	32	struct bio *bio;
33	33	atomic_t io_count;
	34	+ unsigned long start_time;
34	35	};
35	36
36	37	/*
...	...	@@ -244,6 +245,36 @@
244	245	mempool_free(tio, md->tio_pool);
245	246	}
246	247
	248	+static void start_io_acct(struct dm_io *io)
	249	+{
	250	+ struct mapped_device *md = io->md;
	251	+
	252	+ io->start_time = jiffies;
	253	+
	254	+ preempt_disable();
	255	+ disk_round_stats(dm_disk(md));
	256	+ preempt_enable();
	257	+ dm_disk(md)->in_flight = atomic_inc_return(&md->pending);
	258	+}
	259	+
	260	+static int end_io_acct(struct dm_io *io)
	261	+{
	262	+ struct mapped_device *md = io->md;
	263	+ struct bio *bio = io->bio;
	264	+ unsigned long duration = jiffies - io->start_time;
	265	+ int pending;
	266	+ int rw = bio_data_dir(bio);
	267	+
	268	+ preempt_disable();
	269	+ disk_round_stats(dm_disk(md));
	270	+ preempt_enable();
	271	+ dm_disk(md)->in_flight = pending = atomic_dec_return(&md->pending);
	272	+
	273	+ disk_stat_add(dm_disk(md), ticks[rw], duration);
	274	+
	275	+ return !pending;
	276	+}
	277	+
247	278	/*
248	279	* Add the bio to the list of deferred io.
249	280	*/
...	...	@@ -299,7 +330,7 @@
299	330	io->error = error;
300	331
301	332	if (atomic_dec_and_test(&io->io_count)) {
302		- if (atomic_dec_and_test(&io->md->pending))
	333	+ if (end_io_acct(io))
303	334	/* nudge anyone waiting on suspend queue */
304	335	wake_up(&io->md->wait);
305	336
...	...	@@ -554,7 +585,7 @@
554	585	ci.sector_count = bio_sectors(bio);
555	586	ci.idx = bio->bi_idx;
556	587
557		- atomic_inc(&md->pending);
	588	+ start_io_acct(ci.io);
558	589	while (ci.sector_count)
559	590	__clone_and_map(&ci);
560	591