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Merge branch 'for-2.6.39/core' of git://git.kernel.dk/linux-2.6-block

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* '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}
This commit is contained in:
Linus Torvalds
2011-03-24 10:16:26 -07:00
parent 3dab04e697 9d2e157d97
commit 6c51038900
172 changed files with 1538 additions and 2130 deletions
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30
Documentation/cgroups/blkio-controller.txt
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@@ -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.