[PATCH 0/3] blkio: IO controller stats

From: Divyesh Shah
Date: Thu Apr 01 2010 - 18:01:13 EST

The following series implements some additional stats for IO controller.

These stats have helped us debug issues with earlier IO controller
versions and should be useful now as well.
We've been using these stats for monitoring and debugging problems after the
fact as these stats can be collected and stored for later use.

One might argue that most of this information can be exported using blktrace
when debugging. However, blktrace has non-trivial performance impact and
cannot be always turned on. These stats provide a way for continuous monitoring
without losing much performance on rotational disks. We've been able to look
at these stats and debug issues after problems have been reported in the wild
and understand the IO pattern of the affected workloads.
Some of these stats are also a good data source for high-level analysis and
capacity planning.

This patchset adds 4 stats and I will send out another patchset later for
stats like io_merged and some stats that can be turned on only for
debugging - idle_time (total time spent idling for this blkio_group),
wait_time (total time spent by the blkio_group waiting before any one of its
queues got a timeslice). I've tried to breakdown the stats and sent the most
basic ones here.

Divyesh Shah (3):
Increment the blkio cgroup stats for real now.
Add io controller stats like
Remove per-cfqq nr_sectors as we'll be passing that info at request dispatch

block/blk-cgroup.c | 239 ++++++++++++++++++++++++++++++++++++++++++++----
block/blk-cgroup.h | 57 +++++++++--
block/blk-core.c | 6 +
block/cfq-iosched.c | 14 +--
include/linux/blkdev.h | 20 ++++
5 files changed, 291 insertions(+), 45 deletions(-)

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