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authorDivyesh Shah <dpshah@google.com>2010-04-08 21:15:10 -0700
committerJens Axboe <jens.axboe@oracle.com>2010-04-09 08:36:08 +0200
commitcdc1184cf4a7bd99f5473a91244197accc49146b (patch)
treeecd572867bfa5a82fa4ed16d7303448c7ea7d24c /Documentation/cgroups
parent812d402648f4fc1ab1091b2172a46fc1b367c724 (diff)
downloadlinux-linaro-android-cdc1184cf4a7bd99f5473a91244197accc49146b.tar.gz
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<dpshah@google.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'Documentation/cgroups')
-rw-r--r--Documentation/cgroups/blkio-controller.txt11
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
--- a/Documentation/cgroups/blkio-controller.txt
+++ b/Documentation/cgroups/blkio-controller.txt
@@ -139,6 +139,17 @@ Details of cgroup files
cgroup. This is further divided by the type of operation - read or
write, sync or async.
+- blkio.io_queued
+ - 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.
+
+- blkio.avg_queue_size
+ - 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.
+
- blkio.dequeue
- Debugging aid only enabled if CONFIG_DEBUG_CFQ_IOSCHED=y. This
gives the statistics about how many a times a group was dequeued