From cdc1184cf4a7bd99f5473a91244197accc49146b Mon Sep 17 00:00:00 2001 From: Divyesh Shah Date: Thu, 8 Apr 2010 21:15:10 -0700 Subject: 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 Signed-off-by: Jens Axboe --- Documentation/cgroups/blkio-controller.txt | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'Documentation/cgroups') 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 -- cgit v1.2.3