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authorLinus Torvalds <torvalds@linux-foundation.org>2011-03-24 10:16:26 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-03-24 10:16:26 -0700
commit6c5103890057b1bb781b26b7aae38d33e4c517d8 (patch)
treee6e57961dcddcb5841acb34956e70b9dc696a880 /Documentation/cgroups
parent3dab04e6978e358ad2307bca563fabd6c5d2c58b (diff)
parent9d2e157d970a73b3f270b631828e03eb452d525e (diff)
Merge branch 'for-2.6.39/core' of git://git.kernel.dk/linux-2.6-block
* 'for-2.6.39/core' of git://git.kernel.dk/linux-2.6-block: (65 commits) Documentation/iostats.txt: bit-size reference etc. cfq-iosched: removing unnecessary think time checking cfq-iosched: Don't clear queue stats when preempt. blk-throttle: Reset group slice when limits are changed blk-cgroup: Only give unaccounted_time under debug cfq-iosched: Don't set active queue in preempt block: fix non-atomic access to genhd inflight structures block: attempt to merge with existing requests on plug flush block: NULL dereference on error path in __blkdev_get() cfq-iosched: Don't update group weights when on service tree fs: assign sb->s_bdi to default_backing_dev_info if the bdi is going away block: Require subsystems to explicitly allocate bio_set integrity mempool jbd2: finish conversion from WRITE_SYNC_PLUG to WRITE_SYNC and explicit plugging jbd: finish conversion from WRITE_SYNC_PLUG to WRITE_SYNC and explicit plugging fs: make fsync_buffers_list() plug mm: make generic_writepages() use plugging blk-cgroup: Add unaccounted time to timeslice_used. block: fixup plugging stubs for !CONFIG_BLOCK block: remove obsolete comments for blkdev_issue_zeroout. blktrace: Use rq->cmd_flags directly in blk_add_trace_rq. ... Fix up conflicts in fs/{aio.c,super.c}
Diffstat (limited to 'Documentation/cgroups')
-rw-r--r--Documentation/cgroups/blkio-controller.txt30
1 files changed, 1 insertions, 29 deletions
diff --git a/Documentation/cgroups/blkio-controller.txt b/Documentation/cgroups/blkio-controller.txt
index 4ed7b5ceeed2..465351d4cf85 100644
--- a/Documentation/cgroups/blkio-controller.txt
+++ b/Documentation/cgroups/blkio-controller.txt
@@ -140,7 +140,7 @@ Proportional weight policy files
- Specifies per cgroup weight. This is default weight of the group
on all the devices until and unless overridden by per device rule.
(See blkio.weight_device).
- Currently allowed range of weights is from 100 to 1000.
+ Currently allowed range of weights is from 10 to 1000.
- blkio.weight_device
- One can specify per cgroup per device rules using this interface.
@@ -343,34 +343,6 @@ Common files among various policies
CFQ sysfs tunable
=================
-/sys/block/<disk>/queue/iosched/group_isolation
------------------------------------------------
-
-If group_isolation=1, it provides stronger isolation between groups at the
-expense of throughput. By default group_isolation is 0. In general that
-means that if group_isolation=0, expect fairness for sequential workload
-only. Set group_isolation=1 to see fairness for random IO workload also.
-
-Generally CFQ will put random seeky workload in sync-noidle category. CFQ
-will disable idling on these queues and it does a collective idling on group
-of such queues. Generally these are slow moving queues and if there is a
-sync-noidle service tree in each group, that group gets exclusive access to
-disk for certain period. That means it will bring the throughput down if
-group does not have enough IO to drive deeper queue depths and utilize disk
-capacity to the fullest in the slice allocated to it. But the flip side is
-that even a random reader should get better latencies and overall throughput
-if there are lots of sequential readers/sync-idle workload running in the
-system.
-
-If group_isolation=0, then CFQ automatically moves all the random seeky queues
-in the root group. That means there will be no service differentiation for
-that kind of workload. This leads to better throughput as we do collective
-idling on root sync-noidle tree.
-
-By default one should run with group_isolation=0. If that is not sufficient
-and one wants stronger isolation between groups, then set group_isolation=1
-but this will come at cost of reduced throughput.
-
/sys/block/<disk>/queue/iosched/slice_idle
------------------------------------------
On a faster hardware CFQ can be slow, especially with sequential workload.