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authorTejun Heo <tj@kernel.org>2015-08-18 14:55:24 -0700
committerJens Axboe <axboe@fb.com>2015-08-18 15:49:17 -0700
commit77ea733884eb5520f22c36def1309fe2ab61633e (patch)
tree125f3d034cd5c7e57425789f8c23a66368643841 /Documentation/cgroups
parentf12c74cab1635d67077ce8cc40da88b57980f637 (diff)
blkcg: move io_service_bytes and io_serviced stats into blkcg_gq
Currently, both cfq-iosched and blk-throttle keep track of io_service_bytes and io_serviced stats. While keeping track of them separately may be useful during development, it doesn't make much sense otherwise. Also, blk-throttle was counting bio's as IOs while cfq-iosched request's, which is more confusing than informative. This patch adds ->stat_bytes and ->stat_ios to blkg (blkcg_gq), removes the counterparts from cfq-iosched and blk-throttle and let them print from the common blkg counters. The common counters are incremented during bio issue in blkcg_bio_issue_check(). The outputs are still filtered by whether the policy has blkg_policy_data on a given blkg, so cfq's output won't show up if it has never been used for a given blkg. The only times when the outputs would differ significantly are when policies are attached on the fly or elevators are switched back and forth. Those are quite exceptional operations and I don't think they warrant keeping separate counters. v3: Update blkio-controller.txt accordingly. v2: Account IOs during bio issues instead of request completions so that bio-based drivers can be handled the same way. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'Documentation/cgroups')
-rw-r--r--Documentation/cgroups/blkio-controller.txt24
1 files changed, 6 insertions, 18 deletions
diff --git a/Documentation/cgroups/blkio-controller.txt b/Documentation/cgroups/blkio-controller.txt
index 68b6a6a470b0..12686bec37b9 100644
--- a/Documentation/cgroups/blkio-controller.txt
+++ b/Documentation/cgroups/blkio-controller.txt
@@ -201,7 +201,7 @@ Proportional weight policy files
specifies the number of bytes.
- blkio.io_serviced
- - Number of IOs completed to/from the disk by the group. These
+ - Number of IOs (bio) issued to the disk by the group. These
are further divided by the type of operation - read or write, sync
or async. First two fields specify the major and minor number of the
device, third field specifies the operation type and the fourth field
@@ -327,18 +327,11 @@ Note: If both BW and IOPS rules are specified for a device, then IO is
subjected to both the constraints.
- blkio.throttle.io_serviced
- - Number of IOs (bio) completed to/from the disk by the group (as
- seen by throttling policy). These are further divided by the type
- of operation - read or write, sync or async. First two fields specify
- the major and minor number of the device, third field specifies the
- operation type and the fourth field specifies the number of IOs.
-
- blkio.io_serviced does accounting as seen by CFQ and counts are in
- number of requests (struct request). On the other hand,
- blkio.throttle.io_serviced counts number of IO in terms of number
- of bios as seen by throttling policy. These bios can later be
- merged by elevator and total number of requests completed can be
- lesser.
+ - Number of IOs (bio) issued to the disk by the group. These
+ are further divided by the type of operation - read or write, sync
+ or async. First two fields specify the major and minor number of the
+ device, third field specifies the operation type and the fourth field
+ specifies the number of IOs.
- blkio.throttle.io_service_bytes
- Number of bytes transferred to/from the disk by the group. These
@@ -347,11 +340,6 @@ Note: If both BW and IOPS rules are specified for a device, then IO is
device, third field specifies the operation type and the fourth field
specifies the number of bytes.
- These numbers should roughly be same as blkio.io_service_bytes as
- updated by CFQ. The difference between two is that
- blkio.io_service_bytes will not be updated if CFQ is not operating
- on request queue.
-
Common files among various policies
-----------------------------------
- blkio.reset_stats