Eric Lee / smarc-fsl-linux-kernel

24 Oct, 2011

1 commit

23 May, 2011

1 commit

21 May, 2011

3 commits

16 May, 2011

1 commit

  • 70087dc38   blk-throttle: Use task_subsys_state() to determine a task's blkio_cgroup ... Browse Code »

    Currentlly we first map the task to cgroup and then cgroup to
    blkio_cgroup. There is a more direct way to get to blkio_cgroup
    from task using task_subsys_state(). Use that.

    The real reason for the fix is that it also avoids a race in generic
    cgroup code. During remount/umount rebind_subsystems() is called and
    it can do following with and rcu protection.

    cgrp->subsys[i] = NULL;

    That means if somebody got hold of cgroup under rcu and then it tried
    to do cgroup->subsys[] to get to blkio_cgroup, it would get NULL which
    is wrong. I was running into this race condition with ltp running on a
    upstream derived kernel and that lead to crash.

    So ideally we should also fix cgroup generic code to wait for rcu
    grace period before setting pointer to NULL. Li Zefan is not very keen
    on introducing synchronize_wait() as he thinks it will slow
    down moun/remount/umount operations.

    So for the time being atleast fix the kernel crash by taking a more
    direct route to blkio_cgroup.

    One tester had reported a crash while running LTP on a derived kernel
    and with this fix crash is no more seen while the test has been
    running for over 6 days.

    Signed-off-by: Vivek Goyal
    Reviewed-by: Li Zefan
    Signed-off-by: Jens Axboe

    Vivek Goyal
     

12 Mar, 2011

1 commit

  • 167400d34   blk-cgroup: Add unaccounted time to timeslice_used. ... Browse Code »

    There are two kind of times that tasks are not charged for: the first
    seek and the extra time slice used over the allocated timeslice. Both
    of these exported as a new unaccounted_time stat.

    I think it would be good to have this reported in 'time' as well, but
    that is probably a separate discussion.

    Signed-off-by: Justin TerAvest
    Signed-off-by: Jens Axboe

    Justin TerAvest
     

09 Mar, 2011

1 commit

02 Oct, 2010

1 commit

01 Oct, 2010

1 commit

  • fe0714377   blkio: Recalculate the throttled bio dispatch time upon throttle limit change ... Browse Code »

    o Currently any cgroup throttle limit changes are processed asynchronousy and
    the change does not take affect till a new bio is dispatched from same group.

    o It might happen that a user sets a redicuously low limit on throttling.
    Say 1 bytes per second on reads. In such cases simple operations like mount
    a disk can wait for a very long time.

    o Once bio is throttled, there is no easy way to come out of that wait even if
    user increases the read limit later.

    o This patch fixes it. Now if a user changes the cgroup limits, we recalculate
    the bio dispatch time according to new limits.

    o Can't take queueu lock under blkcg_lock, hence after the change I wake
    up the dispatch thread again which recalculates the time. So there are some
    variables being synchronized across two threads without lock and I had to
    make use of barriers. Hoping I have used barriers correctly. Any review of
    memory barrier code especially will help.

    Signed-off-by: Vivek Goyal
    Signed-off-by: Jens Axboe

    Vivek Goyal
     

16 Sep, 2010

3 commits

27 Apr, 2010

2 commits

  • afc24d49c   blk-cgroup: config options re-arrangement ... Browse Code »

    This patch fixes few usability and configurability issues.

    o All the cgroup based controller options are configurable from
    "Genral Setup/Control Group Support/" menu. blkio is the only exception.
    Hence make this option visible in above menu and make it configurable from
    there to bring it inline with rest of the cgroup based controllers.

    o Get rid of CONFIG_DEBUG_CFQ_IOSCHED.

    This option currently does two things.

    - Enable printing of cgroup paths in blktrace
    - Enables CONFIG_DEBUG_BLK_CGROUP, which in turn displays additional stat
    files in cgroup.

    If we are using group scheduling, blktrace data is of not really much use
    if cgroup information is not present. To get this data, currently one has to
    also enable CONFIG_DEBUG_CFQ_IOSCHED, which in turn brings the overhead of
    all the additional debug stat files which is not desired.

    Hence, this patch moves printing of cgroup paths under
    CONFIG_CFQ_GROUP_IOSCHED.

    This allows us to get rid of CONFIG_DEBUG_CFQ_IOSCHED completely. Now all
    the debug stat files are controlled only by CONFIG_DEBUG_BLK_CGROUP which
    can be enabled through config menu.

    Signed-off-by: Vivek Goyal
    Acked-by: Divyesh Shah
    Reviewed-by: Gui Jianfeng
    Signed-off-by: Jens Axboe

    Vivek Goyal
     
  • e5ff082e8   blkio: Fix another BUG_ON() crash due to cfqq movement across groups ... Browse Code »

    o Once in a while, I was hitting a BUG_ON() in blkio code. empty_time was
    assuming that upon slice expiry, group can't be marked empty already (except
    forced dispatch).

    But this assumption is broken if cfqq can move (group_isolation=0) across
    groups after receiving a request.

    I think most likely in this case we got a request in a cfqq and accounted
    the rq in one group, later while adding the cfqq to tree, we moved the queue
    to a different group which was already marked empty and after dispatch from
    slice we found group already marked empty and raised alarm.

    This patch does not error out if group is already marked empty. This can
    introduce some empty_time stat error only in case of group_isolation=0. This
    is better than crashing. In case of group_isolation=1 we should still get
    same stats as before this patch.

    [ 222.308546] ------------[ cut here ]------------
    [ 222.309311] kernel BUG at block/blk-cgroup.c:236!
    [ 222.309311] invalid opcode: 0000 [#1] SMP
    [ 222.309311] last sysfs file: /sys/devices/virtual/block/dm-3/queue/scheduler
    [ 222.309311] CPU 1
    [ 222.309311] Modules linked in: dm_round_robin dm_multipath qla2xxx scsi_transport_fc dm_zero dm_mirror dm_region_hash dm_log dm_mod [last unloaded: scsi_wait_scan]
    [ 222.309311]
    [ 222.309311] Pid: 4780, comm: fio Not tainted 2.6.34-rc4-blkio-config #68 0A98h/HP xw8600 Workstation
    [ 222.309311] RIP: 0010:[] [] blkiocg_set_start_empty_time+0x50/0x83
    [ 222.309311] RSP: 0018:ffff8800ba6e79f8 EFLAGS: 00010002
    [ 222.309311] RAX: 0000000000000082 RBX: ffff8800a13b7990 RCX: ffff8800a13b7808
    [ 222.309311] RDX: 0000000000002121 RSI: 0000000000000082 RDI: ffff8800a13b7a30
    [ 222.309311] RBP: ffff8800ba6e7a18 R08: 0000000000000000 R09: 0000000000000001
    [ 222.309311] R10: 000000000002f8c8 R11: ffff8800ba6e7ad8 R12: ffff8800a13b78ff
    [ 222.309311] R13: ffff8800a13b7990 R14: 0000000000000001 R15: ffff8800a13b7808
    [ 222.309311] FS: 00007f3beec476f0(0000) GS:ffff880001e40000(0000) knlGS:0000000000000000
    [ 222.309311] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    [ 222.309311] CR2: 000000000040e7f0 CR3: 00000000a12d5000 CR4: 00000000000006e0
    [ 222.309311] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
    [ 222.309311] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
    [ 222.309311] Process fio (pid: 4780, threadinfo ffff8800ba6e6000, task ffff8800b3d6bf00)
    [ 222.309311] Stack:
    [ 222.309311] 0000000000000001 ffff8800bab17a48 ffff8800bab17a48 ffff8800a13b7800
    [ 222.309311] ffff8800ba6e7a68 ffffffff8121da35 ffff880000000001 00ff8800ba5c5698
    [ 222.309311] ffff8800ba6e7a68 ffff8800a13b7800 0000000000000000 ffff8800bab17a48
    [ 222.309311] Call Trace:
    [ 222.309311] [] __cfq_slice_expired+0x2af/0x3ec
    [ 222.309311] [] cfq_dispatch_requests+0x2c8/0x8e8
    [ 222.309311] [] ? spin_unlock_irqrestore+0xe/0x10
    [ 222.309311] [] ? blk_insert_cloned_request+0x70/0x7b
    [ 222.309311] [] blk_peek_request+0x191/0x1a7
    [ 222.309311] [] dm_request_fn+0x38/0x14c [dm_mod]
    [ 222.309311] [] ? sync_page_killable+0x0/0x35
    [ 222.309311] [] __generic_unplug_device+0x32/0x37
    [ 222.309311] [] generic_unplug_device+0x2e/0x3c
    [ 222.309311] [] dm_unplug_all+0x42/0x5b [dm_mod]
    [ 222.309311] [] blk_unplug+0x29/0x2d
    [ 222.309311] [] blk_backing_dev_unplug+0x12/0x14
    [ 222.309311] [] block_sync_page+0x35/0x39
    [ 222.309311] [] sync_page+0x41/0x4a
    [ 222.309311] [] sync_page_killable+0xe/0x35
    [ 222.309311] [] __wait_on_bit_lock+0x46/0x8f
    [ 222.309311] [] __lock_page_killable+0x66/0x6d
    [ 222.309311] [] ? wake_bit_function+0x0/0x33
    [ 222.309311] [] lock_page_killable+0x2c/0x2e
    [ 222.309311] [] generic_file_aio_read+0x361/0x4f0
    [ 222.309311] [] do_sync_read+0xcb/0x108
    [ 222.309311] [] ? security_file_permission+0x16/0x18
    [ 222.309311] [] vfs_read+0xab/0x108
    [ 222.309311] [] sys_read+0x4a/0x6e
    [ 222.309311] [] system_call_fastpath+0x16/0x1b
    [ 222.309311] Code: 58 01 00 00 00 48 89 c6 75 0a 48 83 bb 60 01 00 00 00 74 09 48 8d bb a0 00 00 00 eb 35 41 fe cc 74 0d f6 83 c0 01 00 00 04 74 04 0b eb fe 48 89 75 e8 e8 be e0 de ff 66 83 8b c0 01 00 00 04
    [ 222.309311] RIP [] blkiocg_set_start_empty_time+0x50/0x83
    [ 222.309311] RSP
    [ 222.309311] ---[ end trace 32b4f71dffc15712 ]---

    Signed-off-by: Vivek Goyal
    Acked-by: Divyesh Shah
    Signed-off-by: Jens Axboe

    Vivek Goyal
     

16 Apr, 2010

1 commit

14 Apr, 2010

1 commit

  • a11cdaa7a   block: Update to io-controller stats ... Browse Code »

    Changelog from v1:
    o Call blkiocg_update_idle_time_stats() at cfq_rq_enqueued() instead of at
    dispatch time.

    Changelog from original patchset: (in response to Vivek Goyal's comments)
    o group blkiocg_update_blkio_group_dequeue_stats() with other DEBUG functions
    o rename blkiocg_update_set_active_queue_stats() to
    blkiocg_update_avg_queue_size_stats()
    o s/request/io/ in blkiocg_update_request_add_stats() and
    blkiocg_update_request_remove_stats()
    o Call cfq_del_timer() at request dispatch() instead of
    blkiocg_update_idle_time_stats()

    Signed-off-by: Divyesh Shah
    Acked-by: Vivek Goyal
    Signed-off-by: Jens Axboe

    Divyesh Shah
     

13 Apr, 2010

1 commit

  • 34d0f179d   io-controller: Add a new interface "weight_device" for IO-Controller ... Browse Code »

    Currently, IO Controller makes use of blkio.weight to assign weight for
    all devices. Here a new user interface "blkio.weight_device" is introduced to
    assign different weights for different devices. blkio.weight becomes the
    default value for devices which are not configured by "blkio.weight_device"

    You can use the following format to assigned specific weight for a given
    device:
    #echo "major:minor weight" > blkio.weight_device

    major:minor represents device number.

    And you can remove weight for a given device as following:
    #echo "major:minor 0" > blkio.weight_device

    V1->V2 changes:
    - use user interface "weight_device" instead of "policy" suggested by Vivek
    - rename some struct suggested by Vivek
    - rebase to 2.6-block "for-linus" branch
    - remove an useless list_empty check pointed out by Li Zefan
    - some trivial typo fix

    V2->V3 changes:
    - Move policy_*_node() functions up to get rid of forward declarations
    - rename related functions by adding prefix "blkio_"

    Signed-off-by: Gui Jianfeng
    Acked-by: Vivek Goyal
    Signed-off-by: Jens Axboe

    Gui Jianfeng
     

09 Apr, 2010

4 commits

  • 812df48d1   blkio: Add more debug-only per-cgroup stats ... Browse Code »

    1) group_wait_time - This is the amount of time the cgroup had to wait to get a
    timeslice for one of its queues from when it became busy, i.e., went from 0
    to 1 request queued. This is different from the io_wait_time which is the
    cumulative total of the amount of time spent by each IO in that cgroup waiting
    in the scheduler queue. This stat is a great way to find out any jobs in the
    fleet that are being starved or waiting for longer than what is expected (due
    to an IO controller bug or any other issue).
    2) empty_time - This is the amount of time a cgroup spends w/o any pending
    requests. This stat is useful when a job does not seem to be able to use its
    assigned disk share by helping check if that is happening due to an IO
    controller bug or because the job is not submitting enough IOs.
    3) idle_time - This is the amount of time spent by the IO scheduler idling
    for a given cgroup in anticipation of a better request than the exising ones
    from other queues/cgroups.

    All these stats are recorded using start and stop events. When reading these
    stats, we do not add the delta between the current time and the last start time
    if we're between the start and stop events. We avoid doing this to make sure
    that these numbers are always monotonically increasing when read. Since we're
    using sched_clock() which may use the tsc as its source, it may induce some
    inconsistency (due to tsc resync across cpus) if we included the current delta.

    Signed-off-by: Divyesh Shah
    Signed-off-by: Jens Axboe

    Divyesh Shah
     
  • cdc1184cf   blkio: Add io_queued and avg_queue_size stats ... Browse Code »

    These stats are useful for getting a feel for the queue depth of the cgroup,
    i.e., how filled up its queues are at a given instant and over the existence of
    the cgroup. This ability is useful when debugging problems in the wild as it
    helps understand the application's IO pattern w/o having to read through the
    userspace code (coz its tedious or just not available) or w/o the ability
    to run blktrace (since you may not have root access and/or not want to disturb
    performance).

    Signed-off-by: Divyesh Shah
    Signed-off-by: Jens Axboe

    Divyesh Shah
     
  • 812d40264   blkio: Add io_merged stat ... Browse Code »

    This includes both the number of bios merged into requests belonging to this
    cgroup as well as the number of requests merged together.
    In the past, we've observed different merging behavior across upstream kernels,
    some by design some actual bugs. This stat helps a lot in debugging such
    problems when applications report decreased throughput with a new kernel
    version.

    This needed adding an extra elevator function to capture bios being merged as I
    did not want to pollute elevator code with blkiocg knowledge and hence needed
    the accounting invocation to come from CFQ.

    Signed-off-by: Divyesh Shah
    Signed-off-by: Jens Axboe

    Divyesh Shah
     
  • 84c124da9   blkio: Changes to IO controller additional stats patches ... Browse Code »

    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
    Signed-off-by: Jens Axboe

    Divyesh Shah
     

02 Apr, 2010

3 commits

  • 9195291e5   blkio: Increment the blkio cgroup stats for real now ... Browse Code »

    We also add start_time_ns and io_start_time_ns fields to struct request
    here to record the time when a request is created and when it is
    dispatched to device. We use ns uints here as ms and jiffies are
    not very useful for non-rotational media.

    Signed-off-by: Divyesh Shah
    Signed-off-by: Jens Axboe

    Divyesh Shah
     
  • 303a3acb2   blkio: Add io controller stats like ... Browse Code »

    - io_service_time
    - io_wait_time
    - io_serviced
    - io_service_bytes

    These stats are accumulated per operation type helping us to distinguish between
    read and write, and sync and async IO. This patch does not increment any of
    these stats.

    Signed-off-by: Divyesh Shah
    Signed-off-by: Jens Axboe

    Divyesh Shah
     
  • 9a0785b0d   blkio: Remove per-cfqq nr_sectors as we'll be passing ... Browse Code »

    that info at request dispatch with other stats now. This patch removes the
    existing support for accounting sectors for a blkio_group. This will be added
    back differently in the next two patches.

    Signed-off-by: Divyesh Shah
    Signed-off-by: Jens Axboe

    Divyesh Shah
     

13 Mar, 2010

1 commit

  • 67523c48a   cgroups: blkio subsystem as module ... Browse Code »

    Modify the Block I/O cgroup subsystem to be able to be built as a module.
    As the CFQ disk scheduler optionally depends on blk-cgroup, config options
    in block/Kconfig, block/Kconfig.iosched, and block/blk-cgroup.h are
    enhanced to support the new module dependency.

    Signed-off-by: Ben Blum
    Cc: Li Zefan
    Cc: Paul Menage
    Cc: "David S. Miller"
    Cc: KAMEZAWA Hiroyuki
    Cc: Lai Jiangshan
    Cc: Vivek Goyal
    Cc: Jens Axboe
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Ben Blum
     

26 Feb, 2010

1 commit

04 Dec, 2009

7 commits