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  1. 12 Jul, 2011 4 commits
    • Shaohua Li's avatar
      CFQ: add think time check for group · 7700fc4f
      Shaohua Li authored 
      Currently when the last queue of a group has no request, we don't expire
the queue to hope request from the group comes soon, so the group doesn't
miss its share. But if the think time is big, the assumption isn't correct
and we just waste bandwidth. In such case, we don't do idle.

[global]
runtime=30
direct=1

[test1]
cgroup=test1
cgroup_weight=1000
rw=randread
ioengine=libaio
size=500m
runtime=30
directory=/mnt
filename=file1
thinktime=9000

[test2]
cgroup=test2
cgroup_weight=1000
rw=randread
ioengine=libaio
size=500m
runtime=30
directory=/mnt
filename=file2

	patched		base
test1	64k		39k
test2	548k		540k
total	604k		578k

group1 gets much better throughput because it waits less time.

To check if the patch changes behavior of queue without think time. I also
tried to give test1 2ms think time or no think time. The test result is stable.
The thoughput doesn't change with/without the patch.
Signed-off-by: default avatarShaohua Li <shaohua.li@intel.com>
Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
Signed-off-by: default avatarJens Axboe <jaxboe@fusionio.com>
      7700fc4f
    • Shaohua Li's avatar
      CFQ: add think time check for service tree · f5f2b6ce
      Shaohua Li authored 
      Currently when the last queue of a service tree has no request, we don't
expire the queue to hope request from the service tree comes soon, so the
service tree doesn't miss its share. But if the think time is big, the
assumption isn't correct and we just waste bandwidth. In such case, we
don't do idle.

[global]
runtime=10
direct=1

[test1]
rw=randread
ioengine=libaio
size=500m
directory=/mnt
filename=file1
thinktime=9000

[test2]
rw=read
ioengine=libaio
size=1G
directory=/mnt
filename=file2

	patched		base
test1	41k/s		33k/s
test2	15868k/s	15789k/s
total	15902k/s	15817k/s

A slightly better

To check if the patch changes behavior of queue without think time. I also
tried to give test1 2ms think time or no think time. The test has variation
even without the patch, but the average throughput doesn't change with/without
the patch.
Signed-off-by: default avatarShaohua Li <shaohua.li@intel.com>
Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
Signed-off-by: default avatarJens Axboe <jaxboe@fusionio.com>
      f5f2b6ce
    • Shaohua Li's avatar
      CFQ: move think time check variables to a separate struct · 383cd721
      Shaohua Li authored 
      Move the variables to do think time check to a sepatate struct. This is
to prepare adding think time check for service tree and group. No
functional change.
Signed-off-by: default avatarShaohua Li <shaohua.li@intel.com>
Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
Signed-off-by: default avatarJens Axboe <jaxboe@fusionio.com>
      383cd721
    • Justin TerAvest's avatar
      fixlet: Remove fs_excl from struct task. · 4aede84b
      Justin TerAvest authored 
      fs_excl is a poor man's priority inheritance for filesystems to hint to
the block layer that an operation is important. It was never clearly
specified, not widely adopted, and will not prevent starvation in many
cases (like across cgroups).

fs_excl was introduced with the time sliced CFQ IO scheduler, to
indicate when a process held FS exclusive resources and thus needed
a boost.

It doesn't cover all file systems, and it was never fully complete.
Lets kill it.
Signed-off-by: default avatarJustin TerAvest <teravest@google.com>
Signed-off-by: default avatarJens Axboe <jaxboe@fusionio.com>
      4aede84b
  3. 10 Jul, 2011 1 commit
  5. 08 Jul, 2011 2 commits
    • Shaohua Li's avatar
      block: document blk_plug list access · 316cc67d
      Shaohua Li authored 
      I'm often confused why not disable preempt when changing blk_plug list. It
would be better to add comments here in case others have the similar concerns.
Signed-off-by: default avatarShaohua Li <shaohua.li@intel.com>
Signed-off-by: default avatarJens Axboe <jaxboe@fusionio.com>
      316cc67d
    • Shaohua Li's avatar
      block: avoid building too big plug list · 55c022bb
      Shaohua Li authored 
      When I test fio script with big I/O depth, I found the total throughput drops
compared to some relative small I/O depth. The reason is the thread accumulates
big requests in its plug list and causes some delays (surely this depends
on CPU speed).
I thought we'd better have a threshold for requests. When a threshold reaches,
this means there is no request merge and queue lock contention isn't severe
when pushing per-task requests to queue, so the main advantages of blk plug
don't exist. We can force a plug list flush in this case.
With this, my test throughput actually increases and almost equals to small
I/O depth. Another side effect is irq off time decreases in blk_flush_plug_list()
for big I/O depth.
The BLK_MAX_REQUEST_COUNT is choosen arbitarily, but 16 is efficiently to
reduce lock contention to me. But I'm open here, 32 is ok in my test too.
Signed-off-by: default avatarShaohua Li <shaohua.li@intel.com>
Signed-off-by: default avatarJens Axboe <jaxboe@fusionio.com>
      55c022bb
  7. 07 Jul, 2011 1 commit
  9. 06 Jul, 2011 1 commit
    • Mike Snitzer's avatar
      block: eliminate potential for infinite loop in blkdev_issue_discard · 0f799603
      Mike Snitzer authored 
      Due to the recently identified overflow in read_capacity_16() it was
possible for max_discard_sectors to be zero but still have discards
enabled on the associated device's queue.

Eliminate the possibility for blkdev_issue_discard to infinitely loop.

Interestingly this issue wasn't identified until a device, whose
discard_granularity was 0 due to read_capacity_16 overflow, was consumed
by blk_stack_limits() to construct limits for a higher-level DM
multipath device.  The multipath device's resulting limits never had the
discard limits stacked because blk_stack_limits() will only do so if
the bottom device's discard_granularity != 0.  This resulted in the
multipath device's limits.max_discard_sectors being 0.
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
Signed-off-by: default avatarJens Axboe <jaxboe@fusionio.com>
      0f799603
  11. 01 Jul, 2011 3 commits
    • Johannes Stezenbach's avatar
      compat_ioctl: fix warning caused by qemu · 390192b3
      Johannes Stezenbach authored 
      On Linux x86_64 host with 32bit userspace, running
qemu or even just "qemu-img create -f qcow2 some.img 1G"
causes a kernel warning:

ioctl32(qemu-img:5296): Unknown cmd fd(3) cmd(00005326){t:'S';sz:0} arg(7fffffff) on some.img
ioctl32(qemu-img:5296): Unknown cmd fd(3) cmd(801c0204){t:02;sz:28} arg(fff77350) on some.img

ioctl 00005326 is CDROM_DRIVE_STATUS,
ioctl 801c0204 is FDGETPRM.

The warning appears because the Linux compat-ioctl handler for these
ioctls only applies to block devices, while qemu also uses the ioctls on
plain files.
Signed-off-by: default avatarJohannes Stezenbach <js@sig21.net>
Acked-by: default avatarArnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarJens Axboe <jaxboe@fusionio.com>
      390192b3
    • Tejun Heo's avatar
      block: flush MEDIA_CHANGE from drivers on close(2) · 85ef06d1
      Tejun Heo authored 
      Currently, only open(2) is defined as the 'clearing' point.  It has
two roles - first, it's an acknowledgement from userland indicating
that the event has been received and kernel can clear pending states
and proceed to generate more events.  Secondly, it's passed on to
device drivers as a hint indicating that a synchronization point has
been reached and it might want to take a deeper look at the device.

The latter currently is only used by sr which uses two different
mechanisms - GET_EVENT_MEDIA_STATUS_NOTIFICATION and TEST_UNIT_READY
to discover events, where the former is lighter weight and safe to be
used repeatedly but may not provide full coverage.  Among other
things, GET_EVENT can't detect media removal while TUR can.

This patch makes close(2) - blkdev_put() - indicate clearing hint for
MEDIA_CHANGE to drivers.  disk_check_events() is renamed to
disk_flush_events() and updated to take @mask for events to flush
which is or'd to ev->clearing and will be passed to the driver on the
next ->check_events() invocation.

This change makes sr generate MEDIA_CHANGE when media is ejected from
userland - e.g. with eject(1).

Note: Given the current usage, it seems @clearing hint is needlessly
complex.  disk_clear_events() can simply clear all events and the hint
can be boolean @flush.
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: default avatarJens Axboe <jaxboe@fusionio.com>
      85ef06d1
    • Jens Axboe's avatar
      Merge branch 'for-linus' into for-3.1/core · 04bf7869
      Jens Axboe authored 
      Conflicts:
	block/blk-throttle.c
	block/cfq-iosched.c
Signed-off-by: default avatarJens Axboe <jaxboe@fusionio.com>
      04bf7869
  13. 30 Jun, 2011 8 commits
  15. 27 Jun, 2011 4 commits
  17. 25 Jun, 2011 5 commits
  19. 24 Jun, 2011 11 commits
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