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authorMikulas Patocka <mpatocka@redhat.com>2013-08-16 10:54:23 -0400
committerMike Snitzer <snitzer@redhat.com>2013-09-05 20:46:06 -0400
commitfd2ed4d252701d3bbed4cd3e3d267ad469bb832a (patch)
tree264ff043406894bd447eb6e9976b9a2b4d69bd9f /drivers/md/dm.c
parent94563badaf41f9291ff0bad94a443a4319b9e312 (diff)
dm: add statistics support
Support the collection of I/O statistics on user-defined regions of a DM device. If no regions are defined no statistics are collected so there isn't any performance impact. Only bio-based DM devices are currently supported. Each user-defined region specifies a starting sector, length and step. Individual statistics will be collected for each step-sized area within the range specified. The I/O statistics counters for each step-sized area of a region are in the same format as /sys/block/*/stat or /proc/diskstats but extra counters (12 and 13) are provided: total time spent reading and writing in milliseconds. All these counters may be accessed by sending the @stats_print message to the appropriate DM device via dmsetup. The creation of DM statistics will allocate memory via kmalloc or fallback to using vmalloc space. At most, 1/4 of the overall system memory may be allocated by DM statistics. The admin can see how much memory is used by reading /sys/module/dm_mod/parameters/stats_current_allocated_bytes See Documentation/device-mapper/statistics.txt for more details. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Diffstat (limited to 'drivers/md/dm.c')
-rw-r--r--drivers/md/dm.c65
1 files changed, 62 insertions, 3 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 7faeaa3d483..6a5e9ed2fcc 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -60,6 +60,7 @@ struct dm_io {
struct bio *bio;
unsigned long start_time;
spinlock_t endio_lock;
+ struct dm_stats_aux stats_aux;
};
/*
@@ -198,6 +199,8 @@ struct mapped_device {
/* zero-length flush that will be cloned and submitted to targets */
struct bio flush_bio;
+
+ struct dm_stats stats;
};
/*
@@ -269,6 +272,7 @@ static int (*_inits[])(void) __initdata = {
dm_io_init,
dm_kcopyd_init,
dm_interface_init,
+ dm_statistics_init,
};
static void (*_exits[])(void) = {
@@ -279,6 +283,7 @@ static void (*_exits[])(void) = {
dm_io_exit,
dm_kcopyd_exit,
dm_interface_exit,
+ dm_statistics_exit,
};
static int __init dm_init(void)
@@ -384,6 +389,16 @@ int dm_lock_for_deletion(struct mapped_device *md)
return r;
}
+sector_t dm_get_size(struct mapped_device *md)
+{
+ return get_capacity(md->disk);
+}
+
+struct dm_stats *dm_get_stats(struct mapped_device *md)
+{
+ return &md->stats;
+}
+
static int dm_blk_getgeo(struct block_device *bdev, struct hd_geometry *geo)
{
struct mapped_device *md = bdev->bd_disk->private_data;
@@ -466,8 +481,9 @@ static int md_in_flight(struct mapped_device *md)
static void start_io_acct(struct dm_io *io)
{
struct mapped_device *md = io->md;
+ struct bio *bio = io->bio;
int cpu;
- int rw = bio_data_dir(io->bio);
+ int rw = bio_data_dir(bio);
io->start_time = jiffies;
@@ -476,6 +492,10 @@ static void start_io_acct(struct dm_io *io)
part_stat_unlock();
atomic_set(&dm_disk(md)->part0.in_flight[rw],
atomic_inc_return(&md->pending[rw]));
+
+ if (unlikely(dm_stats_used(&md->stats)))
+ dm_stats_account_io(&md->stats, bio->bi_rw, bio->bi_sector,
+ bio_sectors(bio), false, 0, &io->stats_aux);
}
static void end_io_acct(struct dm_io *io)
@@ -491,6 +511,10 @@ static void end_io_acct(struct dm_io *io)
part_stat_add(cpu, &dm_disk(md)->part0, ticks[rw], duration);
part_stat_unlock();
+ if (unlikely(dm_stats_used(&md->stats)))
+ dm_stats_account_io(&md->stats, bio->bi_rw, bio->bi_sector,
+ bio_sectors(bio), true, duration, &io->stats_aux);
+
/*
* After this is decremented the bio must not be touched if it is
* a flush.
@@ -1519,7 +1543,7 @@ static void _dm_request(struct request_queue *q, struct bio *bio)
return;
}
-static int dm_request_based(struct mapped_device *md)
+int dm_request_based(struct mapped_device *md)
{
return blk_queue_stackable(md->queue);
}
@@ -1958,6 +1982,8 @@ static struct mapped_device *alloc_dev(int minor)
md->flush_bio.bi_bdev = md->bdev;
md->flush_bio.bi_rw = WRITE_FLUSH;
+ dm_stats_init(&md->stats);
+
/* Populate the mapping, nobody knows we exist yet */
spin_lock(&_minor_lock);
old_md = idr_replace(&_minor_idr, md, minor);
@@ -2009,6 +2035,7 @@ static void free_dev(struct mapped_device *md)
put_disk(md->disk);
blk_cleanup_queue(md->queue);
+ dm_stats_cleanup(&md->stats);
module_put(THIS_MODULE);
kfree(md);
}
@@ -2150,7 +2177,7 @@ static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t,
/*
* Wipe any geometry if the size of the table changed.
*/
- if (size != get_capacity(md->disk))
+ if (size != dm_get_size(md))
memset(&md->geometry, 0, sizeof(md->geometry));
__set_size(md, size);
@@ -2696,6 +2723,38 @@ out:
return r;
}
+/*
+ * Internal suspend/resume works like userspace-driven suspend. It waits
+ * until all bios finish and prevents issuing new bios to the target drivers.
+ * It may be used only from the kernel.
+ *
+ * Internal suspend holds md->suspend_lock, which prevents interaction with
+ * userspace-driven suspend.
+ */
+
+void dm_internal_suspend(struct mapped_device *md)
+{
+ mutex_lock(&md->suspend_lock);
+ if (dm_suspended_md(md))
+ return;
+
+ set_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags);
+ synchronize_srcu(&md->io_barrier);
+ flush_workqueue(md->wq);
+ dm_wait_for_completion(md, TASK_UNINTERRUPTIBLE);
+}
+
+void dm_internal_resume(struct mapped_device *md)
+{
+ if (dm_suspended_md(md))
+ goto done;
+
+ dm_queue_flush(md);
+
+done:
+ mutex_unlock(&md->suspend_lock);
+}
+
/*-----------------------------------------------------------------
* Event notification.
*---------------------------------------------------------------*/