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author | Divyesh Shah <dpshah@google.com> | 2010-04-09 08:31:19 +0200 |
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committer | Jens Axboe <jens.axboe@oracle.com> | 2010-04-09 08:31:19 +0200 |
commit | 84c124da9ff50bd71fab9c939ee5b7cd8bef2bd9 (patch) | |
tree | f94ad03b56c71ebbe6b92265054c5e24af25b869 /Documentation/cgroups/blkio-controller.txt | |
parent | 31373d09da5b7fe21fe6f781e92bd534a3495f00 (diff) | |
download | linux-84c124da9ff50bd71fab9c939ee5b7cd8bef2bd9.tar.bz2 |
blkio: Changes to IO controller additional stats patches
that include some minor fixes and addresses all comments.
Changelog: (most based on Vivek Goyal's comments)
o renamed blkiocg_reset_write to blkiocg_reset_stats
o more clarification in the documentation on io_service_time and io_wait_time
o Initialize blkg->stats_lock
o rename io_add_stat to blkio_add_stat and declare it static
o use bool for direction and sync
o derive direction and sync info from existing rq methods
o use 12 for major:minor string length
o define io_service_time better to cover the NCQ case
o add a separate reset_stats interface
o make the indexed stats a 2d array to simplify macro and function pointer code
o blkio.time now exports in jiffies as before
o Added stats description in patch description and
Documentation/cgroup/blkio-controller.txt
o Prefix all stats functions with blkio and make them static as applicable
o replace IO_TYPE_MAX with IO_TYPE_TOTAL
o Moved #define constant to top of blk-cgroup.c
o Pass dev_t around instead of char *
o Add note to documentation file about resetting stats
o use BLK_CGROUP_MODULE in addition to BLK_CGROUP config option in #ifdef
statements
o Avoid struct request specific knowledge in blk-cgroup. blk-cgroup.h now has
rq_direction() and rq_sync() functions which are used by CFQ and when using
io-controller at a higher level, bio_* functions can be added.
Signed-off-by: Divyesh Shah<dpshah@google.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'Documentation/cgroups/blkio-controller.txt')
-rw-r--r-- | Documentation/cgroups/blkio-controller.txt | 48 |
1 files changed, 47 insertions, 1 deletions
diff --git a/Documentation/cgroups/blkio-controller.txt b/Documentation/cgroups/blkio-controller.txt index 630879cd9a42..ed04fe9cce1a 100644 --- a/Documentation/cgroups/blkio-controller.txt +++ b/Documentation/cgroups/blkio-controller.txt @@ -77,7 +77,6 @@ Details of cgroup files ======================= - blkio.weight - Specifies per cgroup weight. - Currently allowed range of weights is from 100 to 1000. - blkio.time @@ -92,6 +91,49 @@ Details of cgroup files third field specifies the number of sectors transferred by the group to/from the device. +- blkio.io_service_bytes + - Number of bytes transferred to/from 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 bytes. + +- blkio.io_serviced + - Number of IOs completed to/from 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.io_service_time + - Total amount of time between request dispatch and request completion + for the IOs done by this cgroup. This is in nanoseconds to make it + meaningful for flash devices too. For devices with queue depth of 1, + this time represents the actual service time. When queue_depth > 1, + that is no longer true as requests may be served out of order. This + may cause the service time for a given IO to include the service time + of multiple IOs when served out of order which may result in total + io_service_time > actual time elapsed. This time is 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 + io_service_time in ns. + +- blkio.io_wait_time + - Total amount of time the IOs for this cgroup spent waiting in the + scheduler queues for service. This can be greater than the total time + elapsed since it is cumulative io_wait_time for all IOs. It is not a + measure of total time the cgroup spent waiting but rather a measure of + the wait_time for its individual IOs. For devices with queue_depth > 1 + this metric does not include the time spent waiting for service once + the IO is dispatched to the device but till it actually gets serviced + (there might be a time lag here due to re-ordering of requests by the + device). This is in nanoseconds to make it meaningful for flash + devices too. This time is 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 io_wait_time in ns. + - 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 @@ -99,6 +141,10 @@ Details of cgroup files and minor number of the device and third field specifies the number of times a group was dequeued from a particular device. +- blkio.reset_stats + - Writing an int to this file will result in resetting all the stats + for that cgroup. + CFQ sysfs tunable ================= /sys/block/<disk>/queue/iosched/group_isolation |