|author||Divyesh Shah <firstname.lastname@example.org>||2010-04-08 21:15:10 -0700|
|committer||Jens Axboe <email@example.com>||2010-04-09 08:36:08 +0200|
blkio: Add io_queued and avg_queue_size stats
These stats are useful for getting a feel for the queue depth of the cgroup, i.e., how filled up its queues are at a given instant and over the existence of the cgroup. This ability is useful when debugging problems in the wild as it helps understand the application's IO pattern w/o having to read through the userspace code (coz its tedious or just not available) or w/o the ability to run blktrace (since you may not have root access and/or not want to disturb performance). Signed-off-by: Divyesh Shah<firstname.lastname@example.org> Signed-off-by: Jens Axboe <email@example.com>
Diffstat (limited to 'Documentation/cgroups')
1 files changed, 11 insertions, 0 deletions
diff --git a/Documentation/cgroups/blkio-controller.txt b/Documentation/cgroups/blkio-controller.txt
index 810e30171a5..6e52e7c512a 100644
@@ -139,6 +139,17 @@ Details of cgroup files
cgroup. This is further divided by the type of operation - read or
write, sync or async.
+ - Total number of requests queued up at any given instant for this
+ cgroup. This is further divided by the type of operation - read or
+ write, sync or async.
+ - Debugging aid only enabled if CONFIG_DEBUG_CFQ_IOSCHED=y.
+ The average queue size for this cgroup over the entire time of this
+ cgroup's existence. Queue size samples are taken each time one of the
+ queues of this cgroup gets a timeslice.
- Debugging aid only enabled if CONFIG_DEBUG_CFQ_IOSCHED=y. This
gives the statistics about how many a times a group was dequeued