aha/block
Vivek Goyal ae30c28655 blkio: Implement group_isolation tunable
o If a group is running only a random reader, then it will not have enough
  traffic to keep disk busy and we will reduce overall throughput. This
  should result in better latencies for random reader though. If we don't
  idle on random reader service tree, then this random reader will experience
  large latencies if there are other groups present in system with sequential
  readers running in these.

o One solution suggested by corrado is that by default keep the random readers
  or sync-noidle workload in root group so that during one dispatch round
  we idle only once on sync-noidle tree. This means that all the sync-idle
  workload queues will be in their respective group and we will see service
  differentiation in those but not on sync-noidle workload.

o Provide a tunable group_isolation. If set, this will make sure that even
  sync-noidle queues go in their respective group and we wait on these. This
  provides stronger isolation between groups but at the expense of throughput
  if group does not have enough traffic to keep the disk busy.

o By default group_isolation = 0

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2009-12-03 19:28:53 +01:00
..
blk-barrier.c block: allow large discard requests 2009-10-01 21:19:34 +02:00
blk-cgroup.c blkio: Propagate cgroup weight updation to cfq groups 2009-12-03 19:28:53 +01:00
blk-cgroup.h blkio: Export disk time and sectors used by a group to user space 2009-12-03 19:28:52 +01:00
blk-core.c block: add helpers to run flush_dcache_page() against a bio and a request's pages 2009-11-26 09:16:19 +01:00
blk-exec.c block: don't set REQ_NOMERGE unnecessarily 2009-04-28 07:37:33 +02:00
blk-integrity.c block: fix improper kobject release in blk_integrity_unregister 2009-07-28 09:11:14 +02:00
blk-ioc.c block: prevent possible io_context->refcount overflow 2009-06-10 23:07:15 +02:00
blk-iopoll.c block: use interrupts disabled version of raise_softirq_irqoff() 2009-09-11 14:33:32 +02:00
blk-map.c block: Use accessor functions for queue limits 2009-05-22 23:22:54 +02:00
blk-merge.c block: Seperate read and write statistics of in_flight requests v2 2009-10-06 20:16:55 +02:00
blk-settings.c block: Allow devices to indicate whether discarded blocks are zeroed 2009-12-03 09:24:48 +01:00
blk-softirq.c generic-ipi: remove CSD_FLAG_WAIT 2009-02-25 14:13:44 +01:00
blk-sysfs.c block: Allow devices to indicate whether discarded blocks are zeroed 2009-12-03 09:24:48 +01:00
blk-tag.c block: use proper BLK_RW_ASYNC in blk_queue_start_tag() 2009-10-06 20:19:02 +02:00
blk-timeout.c block: clean up misc stuff after block layer timeout conversion 2009-04-28 07:37:34 +02:00
blk.h block: implement mixed merge of different failfast requests 2009-09-11 14:33:30 +02:00
bsg.c block: jiffies fixes 2009-11-11 13:47:45 +01:00
cfq-iosched.c blkio: Implement group_isolation tunable 2009-12-03 19:28:53 +01:00
compat_ioctl.c block: Allow devices to indicate whether discarded blocks are zeroed 2009-12-03 09:24:48 +01:00
deadline-iosched.c block: convert to pos and nr_sectors accessors 2009-05-11 09:50:54 +02:00
elevator.c Merge branch 'for-linus' into for-2.6.33 2009-10-13 12:29:45 +02:00
genhd.c block: Expose discard granularity 2009-11-10 11:50:21 +01:00
ioctl.c block: Allow devices to indicate whether discarded blocks are zeroed 2009-12-03 09:24:48 +01:00
Kconfig blkio: Some debugging aids for CFQ 2009-12-03 19:28:52 +01:00
Kconfig.iosched blkio: Some debugging aids for CFQ 2009-12-03 19:28:52 +01:00
Makefile blkio: Introduce blkio controller cgroup interface 2009-12-03 19:28:51 +01:00
noop-iosched.c block: get rid of elevator_t typedef 2008-12-29 08:29:50 +01:00
scsi_ioctl.c block/scsi_ioctl.c: quiet sparse noise 2009-11-04 09:10:33 +01:00