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| author | Divyesh Shah <dpshah@google.com> | 2010-04-09 06:15:10 +0200 |
|---|---|---|
| committer | Jens Axboe <jens.axboe@oracle.com> | 2010-04-09 08:36:08 +0200 |
| commit | cdc1184cf4a7bd99f5473a91244197accc49146b (patch) | |
| tree | ecd572867bfa5a82fa4ed16d7303448c7ea7d24c /Documentation/cgroups | |
| parent | blkio: Add io_merged stat (diff) | |
| download | linux-cdc1184cf4a7bd99f5473a91244197accc49146b.tar.xz linux-cdc1184cf4a7bd99f5473a91244197accc49146b.zip | |
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.txt | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/Documentation/cgroups/blkio-controller.txt b/Documentation/cgroups/blkio-controller.txt index 810e30171a54..6e52e7c512a4 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 |