1. 07 Aug, 2010 3 commits
  2. 24 Jun, 2010 1 commit
  3. 21 Jun, 2010 1 commit
  4. 18 Jun, 2010 1 commit
    • Vivek Goyal's avatar
      cfq-iosched: Fixed boot warning with BLK_CGROUP=y and CFQ_GROUP_IOSCHED=n · e98ef89b
      Vivek Goyal authored
      Hi Jens,
      
      Few days back Ingo noticed a CFQ boot time warning. This patch fixes it.
      The issue here is that with CFQ_GROUP_IOSCHED=n, CFQ should not really
      be making blkio stat related calls.
      
      > Hm, it's still not entirely fixed, as of 2.6.35-rc2-00131-g7908a9e5. With
      > some
      > configs i get bad spinlock warnings during bootup:
      >
      > [   28.968013] initcall net_olddevs_init+0x0/0x82 returned 0 after 93750
      > usecs
      > [   28.972003] calling  b44_init+0x0/0x55 @ 1
      > [   28.976009] bus: 'pci': add driver b44
      > [   28.976374]  sda:
      > [   28.978157] BUG: spinlock bad magic on CPU#1, async/0/117
      > [   28.980000]  lock: 7e1c5bbc, .magic: 00000000, .owner: <none>/-1, +.owner_cpu: 0
      > [   28.980000] Pid: 117, comm: async/0 Not tainted +2.6.35-rc2-tip-01092-g010e7ef-dirty #8183
      > [   28.980000] Call Trace:
      > [   28.980000]  [<41ba6d55>] ? printk+0x20/0x24
      > [   28.980000]  [<4134b7b7>] spin_bug+0x7c/0x87
      > [   28.980000]  [<4134b853>] do_raw_spin_lock+0x1e/0x123
      > [   28.980000]  [<41ba92ca>] ? _raw_spin_lock_irqsave+0x12/0x20
      > [   28.980000]  [<41ba92d2>] _raw_spin_lock_irqsave+0x1a/0x20
      > [   28.980000]  [<4133476f>] blkiocg_update_io_add_stats+0x25/0xfb
      > [   28.980000]  [<41335dae>] ? cfq_prio_tree_add+0xb1/0xc1
      > [   28.980000]  [<41337bc7>] cfq_insert_request+0x8c/0x425
      Signed-off-by: default avatarVivek Goyal <vgoyal@redhat.com>
      Signed-off-by: default avatarJens Axboe <jaxboe@fusionio.com>
      e98ef89b
  5. 17 Jun, 2010 2 commits
    • Jeff Moyer's avatar
      cfq: Don't allow queue merges for queues that have no process references · c10b61f0
      Jeff Moyer authored
      Hi,
      
      A user reported a kernel bug when running a particular program that did
      the following:
      
      created 32 threads
      - each thread took a mutex, grabbed a global offset, added a buffer size
        to that offset, released the lock
      - read from the given offset in the file
      - created a new thread to do the same
      - exited
      
      The result is that cfq's close cooperator logic would trigger, as the
      threads were issuing I/O within the mean seek distance of one another.
      This workload managed to routinely trigger a use after free bug when
      walking the list of merge candidates for a particular cfqq
      (cfqq->new_cfqq).  The logic used for merging queues looks like this:
      
      static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
      {
      	int process_refs, new_process_refs;
      	struct cfq_queue *__cfqq;
      
      	/* Avoid a circular list and skip interim queue merges */
      	while ((__cfqq = new_cfqq->new_cfqq)) {
      		if (__cfqq == cfqq)
      			return;
      		new_cfqq = __cfqq;
      	}
      
      	process_refs = cfqq_process_refs(cfqq);
      	/*
      	 * If the process for the cfqq has gone away, there is no
      	 * sense in merging the queues.
      	 */
      	if (process_refs == 0)
      		return;
      
      	/*
      	 * Merge in the direction of the lesser amount of work.
      	 */
      	new_process_refs = cfqq_process_refs(new_cfqq);
      	if (new_process_refs >= process_refs) {
      		cfqq->new_cfqq = new_cfqq;
      		atomic_add(process_refs, &new_cfqq->ref);
      	} else {
      		new_cfqq->new_cfqq = cfqq;
      		atomic_add(new_process_refs, &cfqq->ref);
      	}
      }
      
      When a merge candidate is found, we add the process references for the
      queue with less references to the queue with more.  The actual merging
      of queues happens when a new request is issued for a given cfqq.  In the
      case of the test program, it only does a single pread call to read in
      1MB, so the actual merge never happens.
      
      Normally, this is fine, as when the queue exits, we simply drop the
      references we took on the other cfqqs in the merge chain:
      
      	/*
      	 * If this queue was scheduled to merge with another queue, be
      	 * sure to drop the reference taken on that queue (and others in
      	 * the merge chain).  See cfq_setup_merge and cfq_merge_cfqqs.
      	 */
      	__cfqq = cfqq->new_cfqq;
      	while (__cfqq) {
      		if (__cfqq == cfqq) {
      			WARN(1, "cfqq->new_cfqq loop detected\n");
      			break;
      		}
      		next = __cfqq->new_cfqq;
      		cfq_put_queue(__cfqq);
      		__cfqq = next;
      	}
      
      However, there is a hole in this logic.  Consider the following (and
      keep in mind that each I/O keeps a reference to the cfqq):
      
      q1->new_cfqq = q2   // q2 now has 2 process references
      q3->new_cfqq = q2   // q2 now has 3 process references
      
      // the process associated with q2 exits
      // q2 now has 2 process references
      
      // queue 1 exits, drops its reference on q2
      // q2 now has 1 process reference
      
      // q3 exits, so has 0 process references, and hence drops its references
      // to q2, which leaves q2 also with 0 process references
      
      q4 comes along and wants to merge with q3
      
      q3->new_cfqq still points at q2!  We follow that link and end up at an
      already freed cfqq.
      
      So, the fix is to not follow a merge chain if the top-most queue does
      not have a process reference, otherwise any queue in the chain could be
      already freed.  I also changed the logic to disallow merging with a
      queue that does not have any process references.  Previously, we did
      this check for one of the merge candidates, but not the other.  That
      doesn't really make sense.
      
      Without the attached patch, my system would BUG within a couple of
      seconds of running the reproducer program.  With the patch applied, my
      system ran the program for over an hour without issues.
      
      This addresses the following bugzilla:
          https://bugzilla.kernel.org/show_bug.cgi?id=16217
      
      Thanks a ton to Phil Carns for providing the bug report and an excellent
      reproducer.
      
      [ Note for stable: this applies to 2.6.32/33/34 ].
      Signed-off-by: default avatarJeff Moyer <jmoyer@redhat.com>
      Reported-by: default avatarPhil Carns <carns@mcs.anl.gov>
      Cc: stable@kernel.org
      Signed-off-by: default avatarJens Axboe <jaxboe@fusionio.com>
      c10b61f0
    • Christoph Hellwig's avatar
      block: fix DISCARD_BARRIER requests · fbbf0556
      Christoph Hellwig authored
      Filesystems assume that DISCARD_BARRIER are full barriers, so that they
      don't have to track in-progress discard operation when submitting new I/O.
      But currently we only treat them as elevator barriers, which don't
      actually do the nessecary queue drains.
      
      Also remove the unlikely around both the DISCARD and BARRIER requests -
      the happen far too often for a static mispredict.
      Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
      Signed-off-by: default avatarJens Axboe <jaxboe@fusionio.com>
      fbbf0556
  6. 04 Jun, 2010 2 commits
  7. 25 May, 2010 1 commit
    • Shaohua Li's avatar
      cfq-iosched: fix an oops caused by slab leak · d02a2c07
      Shaohua Li authored
      I got below oops when unloading cfq-iosched. Considering scenario:
      queue A merge to B, C merge to D and B will be merged to D. Before B is merged
      to D, we do split B. We should put B's reference for D.
      
      [  807.768536] =============================================================================
      [  807.768539] BUG cfq_queue: Objects remaining on kmem_cache_close()
      [  807.768541] -----------------------------------------------------------------------------
      [  807.768543]
      [  807.768546] INFO: Slab 0xffffea0003e6b4e0 objects=26 used=1 fp=0xffff88011d584fd8 flags=0x200000000004082
      [  807.768550] Pid: 5946, comm: rmmod Tainted: G        W   2.6.34-07097-gf4b87dee-dirty #724
      [  807.768552] Call Trace:
      [  807.768560]  [<ffffffff81104e8d>] slab_err+0x8f/0x9d
      [  807.768564]  [<ffffffff811059e1>] ? flush_cpu_slab+0x0/0x93
      [  807.768569]  [<ffffffff8164be52>] ? add_preempt_count+0xe/0xca
      [  807.768572]  [<ffffffff8164bd9c>] ? sub_preempt_count+0xe/0xb6
      [  807.768577]  [<ffffffff81648871>] ? _raw_spin_unlock+0x15/0x30
      [  807.768580]  [<ffffffff8164bd9c>] ? sub_preempt_count+0xe/0xb6
      [  807.768584]  [<ffffffff811061bc>] list_slab_objects+0x9b/0x19f
      [  807.768588]  [<ffffffff8164bf0a>] ? add_preempt_count+0xc6/0xca
      [  807.768591]  [<ffffffff81109e27>] kmem_cache_destroy+0x13f/0x21d
      [  807.768597]  [<ffffffffa000ff13>] cfq_slab_kill+0x1a/0x43 [cfq_iosched]
      [  807.768601]  [<ffffffffa000ffcf>] cfq_exit+0x93/0x9e [cfq_iosched]
      [  807.768606]  [<ffffffff810973a2>] sys_delete_module+0x1b1/0x219
      [  807.768612]  [<ffffffff8102fb5b>] system_call_fastpath+0x16/0x1b
      [  807.768618] INFO: Object 0xffff88011d584618 @offset=1560
      [  807.768622] INFO: Allocated in cfq_get_queue+0x11e/0x274 [cfq_iosched] age=7173 cpu=1 pid=5496
      [  807.768626] =============================================================================
      
      Cc: stable@kernel.org
      Signed-off-by: default avatarShaohua Li <shaohua.li@intel.com>
      Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
      d02a2c07
  8. 24 May, 2010 3 commits
  9. 21 May, 2010 1 commit
  10. 11 May, 2010 1 commit
    • Mike Snitzer's avatar
      block: allow initialization of previously allocated request_queue · 01effb0d
      Mike Snitzer authored
      blk_init_queue() allocates the request_queue structure and then
      initializes it as needed (request_fn, elevator, etc).
      
      Split initialization out to blk_init_allocated_queue_node.
      Introduce blk_init_allocated_queue wrapper function to model existing
      blk_init_queue and blk_init_queue_node interfaces.
      
      Export elv_register_queue to allow a newly added elevator to be
      registered with sysfs.  Export elv_unregister_queue for symmetry.
      
      These changes allow DM to initialize a device's request_queue with more
      precision.  In particular, DM no longer unconditionally initializes a
      full request_queue (elevator et al).  It only does so for a
      request-based DM device.
      Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
      Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
      01effb0d
  11. 07 May, 2010 1 commit
  12. 06 May, 2010 1 commit
    • Vivek Goyal's avatar
      blk-cgroup: Fix RCU correctness warning in cfq_init_queue() · dcf097b2
      Vivek Goyal authored
      It is necessary to be in an RCU read-side critical section when invoking
      css_id(), so this patch adds one to blkiocg_add_blkio_group().  This is
      actually a false positive, because this is called at initialization time
      and hence always refers to the root cgroup, which cannot go away.
      
      [  103.790505] ===================================================
      [  103.790509] [ INFO: suspicious rcu_dereference_check() usage. ]
      [  103.790511] ---------------------------------------------------
      [  103.790514] kernel/cgroup.c:4432 invoked rcu_dereference_check() without protection!
      [  103.790517]
      [  103.790517] other info that might help us debug this:
      [  103.790519]
      [  103.790521]
      [  103.790521] rcu_scheduler_active = 1, debug_locks = 1
      [  103.790524] 4 locks held by bash/4422:
      [  103.790526]  #0:  (&buffer->mutex){+.+.+.}, at: [<ffffffff8114befa>] sysfs_write_file+0x3c/0x144
      [  103.790537]  #1:  (s_active#102){.+.+.+}, at: [<ffffffff8114bfa5>] sysfs_write_file+0xe7/0x144
      [  103.790544]  #2:  (&q->sysfs_lock){+.+.+.}, at: [<ffffffff812263b1>] queue_attr_store+0x49/0x8f
      [  103.790552]  #3:  (&(&blkcg->lock)->rlock){......}, at: [<ffffffff8122e4db>] blkiocg_add_blkio_group+0x2b/0xad
      [  103.790560]
      [  103.790561] stack backtrace:
      [  103.790564] Pid: 4422, comm: bash Not tainted 2.6.34-rc4-blkio-second-crash #81
      [  103.790567] Call Trace:
      [  103.790572]  [<ffffffff81068f57>] lockdep_rcu_dereference+0x9d/0xa5
      [  103.790577]  [<ffffffff8107fac1>] css_id+0x44/0x57
      [  103.790581]  [<ffffffff8122e503>] blkiocg_add_blkio_group+0x53/0xad
      [  103.790586]  [<ffffffff81231936>] cfq_init_queue+0x139/0x32c
      [  103.790591]  [<ffffffff8121f2d0>] elv_iosched_store+0xbf/0x1bf
      [  103.790595]  [<ffffffff812263d8>] queue_attr_store+0x70/0x8f
      [  103.790599]  [<ffffffff8114bfa5>] ? sysfs_write_file+0xe7/0x144
      [  103.790603]  [<ffffffff8114bfc6>] sysfs_write_file+0x108/0x144
      [  103.790609]  [<ffffffff810f527f>] vfs_write+0xae/0x10b
      [  103.790612]  [<ffffffff81069863>] ? trace_hardirqs_on_caller+0x10c/0x130
      [  103.790616]  [<ffffffff810f539c>] sys_write+0x4a/0x6e
      [  103.790622]  [<ffffffff81002b5b>] system_call_fastpath+0x16/0x1b
      [  103.790625]
      Located-by: default avatarMiles Lane <miles.lane@gmail.com>
      Signed-off-by: default avatarVivek Goyal <vgoyal@redhat.com>
      Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
      dcf097b2
  13. 03 May, 2010 1 commit
  14. 29 Apr, 2010 1 commit
  15. 28 Apr, 2010 5 commits
  16. 26 Apr, 2010 2 commits
    • Vivek Goyal's avatar
      blk-cgroup: config options re-arrangement · afc24d49
      Vivek Goyal authored
      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: default avatarVivek Goyal <vgoyal@redhat.com>
      Acked-by: default avatarDivyesh Shah <dpshah@google.com>
      Reviewed-by: default avatarGui Jianfeng <guijianfeng@cn.fujitsu.com>
      Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
      afc24d49
    • Vivek Goyal's avatar
      blkio: Fix another BUG_ON() crash due to cfqq movement across groups · e5ff082e
      Vivek Goyal authored
      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:[<ffffffff8121ad88>]  [<ffffffff8121ad88>] 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] <0> ffff8800ba6e7a68 ffffffff8121da35 ffff880000000001 00ff8800ba5c5698
      [  222.309311] <0> ffff8800ba6e7a68 ffff8800a13b7800 0000000000000000 ffff8800bab17a48
      [  222.309311] Call Trace:
      [  222.309311]  [<ffffffff8121da35>] __cfq_slice_expired+0x2af/0x3ec
      [  222.309311]  [<ffffffff8121fd7b>] cfq_dispatch_requests+0x2c8/0x8e8
      [  222.309311]  [<ffffffff8120f1cd>] ? spin_unlock_irqrestore+0xe/0x10
      [  222.309311]  [<ffffffff8120fb1a>] ? blk_insert_cloned_request+0x70/0x7b
      [  222.309311]  [<ffffffff81210461>] blk_peek_request+0x191/0x1a7
      [  222.309311]  [<ffffffffa0002799>] dm_request_fn+0x38/0x14c [dm_mod]
      [  222.309311]  [<ffffffff810ae61f>] ? sync_page_killable+0x0/0x35
      [  222.309311]  [<ffffffff81210fd4>] __generic_unplug_device+0x32/0x37
      [  222.309311]  [<ffffffff81211274>] generic_unplug_device+0x2e/0x3c
      [  222.309311]  [<ffffffffa00011a6>] dm_unplug_all+0x42/0x5b [dm_mod]
      [  222.309311]  [<ffffffff8120ca37>] blk_unplug+0x29/0x2d
      [  222.309311]  [<ffffffff8120ca4d>] blk_backing_dev_unplug+0x12/0x14
      [  222.309311]  [<ffffffff81109a7a>] block_sync_page+0x35/0x39
      [  222.309311]  [<ffffffff810ae616>] sync_page+0x41/0x4a
      [  222.309311]  [<ffffffff810ae62d>] sync_page_killable+0xe/0x35
      [  222.309311]  [<ffffffff8158aa59>] __wait_on_bit_lock+0x46/0x8f
      [  222.309311]  [<ffffffff810ae4f5>] __lock_page_killable+0x66/0x6d
      [  222.309311]  [<ffffffff81056f9c>] ? wake_bit_function+0x0/0x33
      [  222.309311]  [<ffffffff810ae528>] lock_page_killable+0x2c/0x2e
      [  222.309311]  [<ffffffff810afbc5>] generic_file_aio_read+0x361/0x4f0
      [  222.309311]  [<ffffffff810ea044>] do_sync_read+0xcb/0x108
      [  222.309311]  [<ffffffff811e42f7>] ? security_file_permission+0x16/0x18
      [  222.309311]  [<ffffffff810ea6ab>] vfs_read+0xab/0x108
      [  222.309311]  [<ffffffff810ea7c8>] sys_read+0x4a/0x6e
      [  222.309311]  [<ffffffff81002b5b>] 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 <0f> 0b eb fe 48 89 75 e8 e8 be e0 de ff 66 83 8b c0 01 00 00 04
      [  222.309311] RIP  [<ffffffff8121ad88>] blkiocg_set_start_empty_time+0x50/0x83
      [  222.309311]  RSP <ffff8800ba6e79f8>
      [  222.309311] ---[ end trace 32b4f71dffc15712 ]---
      Signed-off-by: default avatarVivek Goyal <vgoyal@redhat.com>
      Acked-by: default avatarDivyesh Shah <dpshah@google.com>
      Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
      e5ff082e
  17. 21 Apr, 2010 2 commits
    • Vivek Goyal's avatar
      blkio: Fix blkio crash during rq stat update · 7f1dc8a2
      Vivek Goyal authored
      blkio + cfq was crashing even when two sequential readers were put in two
      separate cgroups (group_isolation=0).
      
      The reason being that cfqq can migrate across groups based on its being
      sync-noidle or not, it can happen that at request insertion time, cfqq
      belonged to one cfqg and at request dispatch time, it belonged to root
      group. In this case request stats per cgroup can go wrong and it also runs
      into BUG_ON().
      
      This patch implements rq stashing away a cfq group pointer and not relying
      on cfqq->cfqg pointer alone for rq stat accounting.
      
      [   65.163523] ------------[ cut here ]------------
      [   65.164301] kernel BUG at block/blk-cgroup.c:117!
      [   65.164301] invalid opcode: 0000 [#1] SMP
      [   65.164301] last sysfs file: /sys/devices/pci0000:00/0000:00:05.0/0000:60:00.1/host9/rport-9:0-0/target9:0:0/9:0:0:2/block/sde/stat
      [   65.164301] CPU 1
      [   65.164301] 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]
      [   65.164301]
      [   65.164301] Pid: 4505, comm: fio Not tainted 2.6.34-rc4-blk-for-35 #34 0A98h/HP xw8600 Workstation
      [   65.164301] RIP: 0010:[<ffffffff8121924f>]  [<ffffffff8121924f>] blkiocg_update_io_remove_stats+0x5b/0xaf
      [   65.164301] RSP: 0018:ffff8800ba5a79e8  EFLAGS: 00010046
      [   65.164301] RAX: 0000000000000096 RBX: ffff8800bb268d60 RCX: 0000000000000000
      [   65.164301] RDX: ffff8800bb268eb8 RSI: 0000000000000000 RDI: ffff8800bb268e00
      [   65.164301] RBP: ffff8800ba5a7a08 R08: 0000000000000064 R09: 0000000000000001
      [   65.164301] R10: 0000000000079640 R11: ffff8800a0bd5bf0 R12: ffff8800bab4af01
      [   65.164301] R13: ffff8800bab4af00 R14: ffff8800bb1d8928 R15: 0000000000000000
      [   65.164301] FS:  00007f18f75056f0(0000) GS:ffff880001e40000(0000) knlGS:0000000000000000
      [   65.164301] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
      [   65.164301] CR2: 000000000040e7f0 CR3: 00000000ba52b000 CR4: 00000000000006e0
      [   65.164301] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
      [   65.164301] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
      [   65.164301] Process fio (pid: 4505, threadinfo ffff8800ba5a6000, task ffff8800ba45ae80)
      [   65.164301] Stack:
      [   65.164301]  ffff8800ba5a7a08 ffff8800ba722540 ffff8800bab4af68 ffff8800bab4af68
      [   65.164301] <0> ffff8800ba5a7a38 ffffffff8121d814 ffff8800ba722540 ffff8800bab4af68
      [   65.164301] <0> ffff8800ba722540 ffff8800a08f6800 ffff8800ba5a7a68 ffffffff8121d8ca
      [   65.164301] Call Trace:
      [   65.164301]  [<ffffffff8121d814>] cfq_remove_request+0xe4/0x116
      [   65.164301]  [<ffffffff8121d8ca>] cfq_dispatch_insert+0x84/0xe1
      [   65.164301]  [<ffffffff8121e833>] cfq_dispatch_requests+0x767/0x8e8
      [   65.164301]  [<ffffffff8120e524>] ? submit_bio+0xc3/0xcc
      [   65.164301]  [<ffffffff810ad657>] ? sync_page_killable+0x0/0x35
      [   65.164301]  [<ffffffff8120ea8d>] blk_peek_request+0x191/0x1a7
      [   65.164301]  [<ffffffffa000109c>] ? dm_get_live_table+0x44/0x4f [dm_mod]
      [   65.164301]  [<ffffffffa0002799>] dm_request_fn+0x38/0x14c [dm_mod]
      [   65.164301]  [<ffffffff810ad657>] ? sync_page_killable+0x0/0x35
      [   65.164301]  [<ffffffff8120f600>] __generic_unplug_device+0x32/0x37
      [   65.164301]  [<ffffffff8120f8a0>] generic_unplug_device+0x2e/0x3c
      [   65.164301]  [<ffffffffa00011a6>] dm_unplug_all+0x42/0x5b [dm_mod]
      [   65.164301]  [<ffffffff8120b063>] blk_unplug+0x29/0x2d
      [   65.164301]  [<ffffffff8120b079>] blk_backing_dev_unplug+0x12/0x14
      [   65.164301]  [<ffffffff81108a82>] block_sync_page+0x35/0x39
      [   65.164301]  [<ffffffff810ad64e>] sync_page+0x41/0x4a
      [   65.164301]  [<ffffffff810ad665>] sync_page_killable+0xe/0x35
      [   65.164301]  [<ffffffff81589027>] __wait_on_bit_lock+0x46/0x8f
      [   65.164301]  [<ffffffff810ad52d>] __lock_page_killable+0x66/0x6d
      [   65.164301]  [<ffffffff81055fd4>] ? wake_bit_function+0x0/0x33
      [   65.164301]  [<ffffffff810ad560>] lock_page_killable+0x2c/0x2e
      [   65.164301]  [<ffffffff810aebfd>] generic_file_aio_read+0x361/0x4f0
      [   65.164301]  [<ffffffff810e906c>] do_sync_read+0xcb/0x108
      [   65.164301]  [<ffffffff811e32a3>] ? security_file_permission+0x16/0x18
      [   65.164301]  [<ffffffff810e96d3>] vfs_read+0xab/0x108
      [   65.164301]  [<ffffffff810e97f0>] sys_read+0x4a/0x6e
      [   65.164301]  [<ffffffff81002b5b>] system_call_fastpath+0x16/0x1b
      [   65.164301] Code: 00 74 1c 48 8b 8b 60 01 00 00 48 85 c9 75 04 0f 0b eb fe 48 ff c9 48 89 8b 60 01 00 00 eb 1a 48 8b 8b 58 01 00 00 48 85 c9 75 04 <0f> 0b eb fe 48 ff c9 48 89 8b 58 01 00 00 45 84 e4 74 16 48 8b
      [   65.164301] RIP  [<ffffffff8121924f>] blkiocg_update_io_remove_stats+0x5b/0xaf
      [   65.164301]  RSP <ffff8800ba5a79e8>
      [   65.164301] ---[ end trace 1b2b828753032e68 ]---
      Signed-off-by: default avatarVivek Goyal <vgoyal@redhat.com>
      Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
      7f1dc8a2
    • Richard Kennedy's avatar
      block: ensure jiffies wrap is handled correctly in blk_rq_timed_out_timer · a534dbe9
      Richard Kennedy authored
      blk_rq_timed_out_timer() relied on blk_add_timer() never returning a
      timer value of zero, but commit 7838c15b
      removed the code that bumped this value when it was zero.
      Therefore when jiffies is near wrap we could get unlucky & not set the
      timeout value correctly.
      
      This patch uses a flag to indicate that the timeout value was set and so
      handles jiffies wrap correctly, and it keeps all the logic in one
      function so should be easier to maintain in the future.
      Signed-off-by: default avatarRichard Kennedy <richard@rsk.demon.co.uk>
      Cc: stable@kernel.org
      Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
      a534dbe9
  18. 16 Apr, 2010 1 commit
  19. 15 Apr, 2010 1 commit
  20. 14 Apr, 2010 2 commits
  21. 13 Apr, 2010 2 commits
    • Divyesh Shah's avatar
      block: Update to io-controller stats · a11cdaa7
      Divyesh Shah authored
      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<dpshah@google.com>
      Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
      Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
      a11cdaa7
    • Gui Jianfeng's avatar
      io-controller: Add a new interface "weight_device" for IO-Controller · 34d0f179
      Gui Jianfeng authored
      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: default avatarGui Jianfeng <guijianfeng@cn.fujitsu.com>
      Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
      Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
      34d0f179
  22. 09 Apr, 2010 5 commits
    • Divyesh Shah's avatar
      cfq-iosched: Fix the incorrect timeslice accounting with forced_dispatch · 3440c49f
      Divyesh Shah authored
      When CFQ dispatches requests forcefully due to a barrier or changing iosched,
      it runs through all cfqq's dispatching requests and then expires each queue.
      However, it does not activate a cfqq before flushing its IOs resulting in
      using stale values for computing slice_used.
      This patch fixes it by calling activate queue before flushing reuqests from
      each queue.
      
      This is useful mostly for barrier requests because when the iosched is changing
      it really doesnt matter if we have incorrect accounting since we're going to
      break down all structures anyway.
      
      We also now expire the current timeslice before moving on with the dispatch
      to accurately account slice used for that cfqq.
      
      Signed-off-by: Divyesh Shah<dpshah@google.com>
      Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
      3440c49f
    • Divyesh Shah's avatar
      blkio: Add more debug-only per-cgroup stats · 812df48d
      Divyesh Shah authored
      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<dpshah@google.com>
      Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
      812df48d
    • Divyesh Shah's avatar
      blkio: Add io_queued and avg_queue_size stats · cdc1184c
      Divyesh Shah authored
      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<dpshah@google.com>
      Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
      cdc1184c
    • Divyesh Shah's avatar
      blkio: Add io_merged stat · 812d4026
      Divyesh Shah authored
      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<dpshah@google.com>
      Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
      812d4026
    • Divyesh Shah's avatar
      blkio: Changes to IO controller additional stats patches · 84c124da
      Divyesh Shah authored
      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<dpshah@google.com>
      Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
      84c124da