1. 14 May, 2013 33 commits
    • Tejun Heo's avatar
      blk-throttle: implement proper hierarchy support · 9138125b
      Tejun Heo authored
      With the recent updates, blk-throttle is finally ready for proper
      hierarchy support.  Dispatching now honors service_queue->parent_sq
      and propagates correctly.  The only thing missing is setting
      ->parent_sq correctly so that throtl_grp hierarchy matches the cgroup
      hierarchy.
      
      This patch updates throtl_pd_init() such that service_queues form the
      same hierarchy as the cgroup hierarchy if sane_behavior is enabled.
      As this concludes proper hierarchy support for blkcg, the shameful
      .broken_hierarchy tag is removed from blkio_subsys.
      
      v2: Updated blkio-controller.txt as suggested by Vivek.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
      Cc: Li Zefan <lizefan@huawei.com>
      9138125b
    • Tejun Heo's avatar
      blk-throttle: implement throtl_grp->has_rules[] · 693e751e
      Tejun Heo authored
      blk_throtl_bio() has a quick exit path for throtl_grps without limits
      configured.  It looks at the bps and iops limits and if both are not
      configured, the bio is issued immediately.  While this is correct in
      the current flat hierarchy as each throtl_grp behaves completely
      independently, it would become wrong in proper hierarchy mode.  A
      group without any limits could still be limited by one of its
      ancestors and bio's queued for such group should not bypass
      blk-throtl.
      
      As having a quick bypass mechanism is beneficial, this patch
      reimplements the mechanism such that it's correct even with proper
      hierarchy.  throtl_grp->has_rules[] is added.  These booleans are
      updated for the whole subtree whenever a config is updated so that
      has_rules[] of the whole subtree stays synchronized.  They're also
      updated when a new throtl_grp comes online so that it can't escape the
      limits of its ancestors.
      
      As no throtl_grp has another throtl_grp as parent now, this patch
      doesn't yet make any behavior differences.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
      693e751e
    • Vivek Goyal's avatar
      blk-throttle: Account for child group's start time in parent while bio climbs up · 32ee5bc4
      Vivek Goyal authored
      With the planned proper hierarchy support, a bio will climb up the
      tree before actually being dispatched. This makes sure bio is also
      subjected to parent's throttling limits, if any.
      
      It might happen that parent is idle and when bio is transferred to
      parent, a new slice starts fresh. But that is incorrect as parents
      wait time should have started when bio was queued in child group and
      causes IOs to be throttled more than configured as they climb the
      hierarchy.
      
      Given the fact that we have not written hierarchical algorithm in a
      way where child's and parents time slices are synchronized, we
      transfer the child's start time to parent if parent was idling.  If
      parent was busy doing dispatch of other bios all this while, this is
      not an issue.
      
      Child's slice start time is passed to parent. Parent looks at its
      last expired slice start time. If child's start time is after parents
      old start time, that means parent had been idle and after parent
      went idle, child had an IO queued. So use child's start time as
      parent start time.
      
      If parent's start time is after child's start time, that means,
      when IO got queued in child group, parent was not idle. But later
      it dispatched some IO, its slice got trimmed and then it went idle.
      After a while child's request got shifted in parent group. In this
      case use parent's old start time as new start time as that's the
      duration of slice we did not use.
      
      This logic is far from perfect as if there are multiple childs
      then first child transferring the bio decides the start time while
      a bio might have queued up even earlier in other child, which is
      yet to be transferred up to parent. In that case we will lose
      time and bandwidth in parent. This patch is just an approximation
      to make situation somewhat better.
      Signed-off-by: default avatarVivek Goyal <vgoyal@redhat.com>
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      32ee5bc4
    • Tejun Heo's avatar
      blk-throttle: add throtl_qnode for dispatch fairness · c5cc2070
      Tejun Heo authored
      With flat hierarchy, there's only single level of dispatching
      happening and fairness beyond that point is the responsibility of the
      rest of the block layer and driver, which usually works out okay;
      however, with the planned hierarchy support,
      service_queue->bio_lists[] can be filled up by bios from a single
      source.  While the limits would still be honored, it'd be very easy to
      starve IOs from siblings or children.
      
      To avoid such starvation, this patch implements throtl_qnode and
      converts service_queue->bio_lists[] to lists of per-source qnodes
      which in turn contains the bio's.  For example, when a bio is
      dispatched from a child group, the bio doesn't get queued on
      ->bio_lists[] directly but it first gets queued on the group's qnode
      which in turn gets queued on service_queue->queued[].  When
      dispatching for the upper level, the ->queued[] list is consumed in
      round-robing order so that the dispatch windows is consumed fairly by
      all IO sources.
      
      There are two ways a bio can come to a throtl_grp - directly queued to
      the group or dispatched from a child.  For the former
      throtl_grp->qnode_on_self[rw] is used.  For the latter, the child's
      ->qnode_on_parent[rw].
      
      Note that this means that the child which is contributing a bio to its
      parent should stay pinned until all its bios are dispatched to its
      grand-parent.  This patch moves blkg refcnting from bio add/remove
      spots to qnode activation/deactivation so that the blkg containing an
      active qnode is always pinned.  As child pins the parent, this is
      sufficient for keeping the relevant sub-tree pinned while bios are in
      flight.
      
      The starvation issue was spotted by Vivek Goyal.
      
      v2: The original patch used the same throtl_grp->qnode_on_self/parent
          for reads and writes causing RWs to be queued incorrectly if there
          already are outstanding IOs in the other direction.  They should
          be throtl_grp->qnode_on_self/parent[2] so that READs and WRITEs
          can use different qnodes.  Spotted by Vivek Goyal.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
      c5cc2070
    • Tejun Heo's avatar
      blk-throttle: make throtl_pending_timer_fn() ready for hierarchy · 2e48a530
      Tejun Heo authored
      throtl_pending_timer_fn() currently assumes that the parent_sq is the
      top level one and the bio's dispatched are ready to be issued;
      however, this assumption will be wrong with proper hierarchy support.
      This patch makes the following changes to make
      throtl_pending_timer_fn() ready for hiearchy.
      
      * If the parent_sq isn't the top-level one, update the parent
        throtl_grp's dispatch time and schedule the next dispatch as
        necessary.  If the parent's dispatch time is now, repeat the
        function for the parent throtl_grp.
      
      * If the parent_sq is the top-level one, kick issue work_item as
        before.
      
      * The debug message printed by throtl_log() now prints out the
        service_queue's nr_queued[] instead of the total nr_queued as the
        latter becomes uninteresting and misleading with hierarchical
        dispatch.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
      2e48a530
    • Tejun Heo's avatar
      blk-throttle: make tg_dispatch_one_bio() ready for hierarchy · 6bc9c2b4
      Tejun Heo authored
      tg_dispatch_one_bio() currently assumes that the parent_sq is the top
      level one and the bio being dispatched is ready to be issued; however,
      this assumption will be wrong with proper hierarchy support.  This
      patch makes the following changes to make tg_dispatch_on_bio() ready
      for hiearchy.
      
      * throtl_data->nr_queued[] is incremented in blk_throtl_bio() instead
        of throtl_add_bio_tg() so that throtl_add_bio_tg() can be used to
        transfer a bio from a child tg to its parent.
      
      * tg_dispatch_one_bio() is updated to distinguish whether its parent
        is another throtl_grp or the throtl_data.  If former, the bio is
        transferred to the parent throtl_grp using throtl_add_bio_tg().  If
        latter, the bio is ready to be issued and put on the top-level
        service_queue's bio_lists[] and throtl_data->nr_queued is
        decremented.
      
      As all throtl_grps currently have the top level service_queue as their
      ->parent_sq, this patch in itself doesn't make any behavior
      difference.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
      6bc9c2b4
    • Tejun Heo's avatar
      blk-throttle: make blk_throtl_bio() ready for hierarchy · 9e660acf
      Tejun Heo authored
      Currently, blk_throtl_bio() issues the passed in bio directly if it's
      within limits of its associated tg (throtl_grp).  This behavior
      becomes incorrect with hierarchy support as the bio should be
      accounted to and throttled by the ancestor throtl_grps too.
      
      This patch makes the direct issue path of blk_throtl_bio() to loop
      until it reaches the top-level service_queue or gets throttled.  If
      the former, the bio can be issued directly; otherwise, it gets queued
      at the first layer it was above limits.
      
      As tg->parent_sq is always the top-level service queue currently, this
      patch in itself doesn't make any behavior differences.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
      9e660acf
    • Tejun Heo's avatar
      blk-throttle: make blk_throtl_drain() ready for hierarchy · 2a12f0dc
      Tejun Heo authored
      The current blk_throtl_drain() assumes that all active throtl_grps are
      queued on throtl_data->service_queue, which won't be true once
      hierarchy support is implemented.
      
      This patch makes blk_throtl_drain() perform post-order walk of the
      blkg hierarchy draining each associated throtl_grp, which guarantees
      that all bios will eventually be pushed to the top-level service_queue
      in throtl_data.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
      2a12f0dc
    • Tejun Heo's avatar
      blk-throttle: dispatch from throtl_pending_timer_fn() · 6e1a5704
      Tejun Heo authored
      Currently, blk_throtl_dispatch_work_fn() is responsible for both
      dispatching bio's from throtl_grp's according to their limits and then
      issuing the dispatched bios.
      
      This patch moves the dispatch part to throtl_pending_timer_fn() so
      that the work item is kicked iff there are bio's to issue.  This is to
      avoid work item execution at each step when hierarchy support is
      enabled.  bio's will be dispatched towards the top-level service_queue
      from the timers at each layer and the work item will only be used to
      issue the bio's which reached the top-level service_queue.
      
      While fetching bio's to issue from bio_lists[],
      blk_throtl_dispatch_work_fn() fetches all READs before WRITEs.  While
      the original code also dispatched READs first, if multiple throtl_grps
      are dispatched on the same run, WRITEs from throtl_grp which is
      dispatched first would precede READs from throtl_grps which are
      dispatched later.  While this is a behavior change, given that the
      previous code already prioritized READs and block layer generally
      prioritizes and segregates READs from WRITEs, this isn't likely to
      make any noticeable differences.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
      6e1a5704
    • Tejun Heo's avatar
      blk-throttle: implement dispatch looping · 7f52f98c
      Tejun Heo authored
      throtl_select_dispatch() only dispatches throtl_quantum bios on each
      invocation.  blk_throtl_dispatch_work_fn() in turn depends on
      throtl_schedule_next_dispatch() scheduling the next dispatch window
      immediately so that undue delays aren't incurred.  This effectively
      chains multiple dispatch work item executions back-to-back when there
      are more than throtl_quantum bios to dispatch on a given tick.
      
      There is no reason to finish the current work item just to repeat it
      immediately.  This patch makes throtl_schedule_next_dispatch() return
      %false without doing anything if the current dispatch window is still
      open and updates blk_throtl_dispatch_work_fn() repeat dispatching
      after cpu_relax() on %false return.
      
      This change will help implementing hierarchy support as dispatching
      will be done from pending_timer and immediate reschedule of timer
      function isn't supported and doesn't make much sense.
      
      While this patch changes how dispatch behaves when there are more than
      throtl_quantum bios to dispatch on a single tick, the behavior change
      is immaterial.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
      7f52f98c
    • Tejun Heo's avatar
      blk-throttle: separate out throtl_service_queue->pending_timer from throtl_data->dispatch_work · 69df0ab0
      Tejun Heo authored
      Currently, throtl_data->dispatch_work is a delayed_work item which
      handles both delayed dispatch and issuing bios.  The two tasks will be
      separated to support proper hierarchy.  To prepare for that, this
      patch separates out the timer into throtl_service_queue->pending_timer
      from throtl_data->dispatch_work and make the latter a work_struct.
      
      * As the timer is now per-service_queue, it's initialized and
        del_sync'd as its corresponding service_queue is created and
        destroyed.  The timer, when triggered, simply schedules
        throtl_data->dispathc_work for execution.
      
      * throtl_schedule_delayed_work() is renamed to
        throtl_schedule_pending_timer() and takes @sq and @expires now.
      
      * Simiarly, throtl_schedule_next_dispatch() now takes @sq, which
        should be the parent_sq of the service_queue which just got a new
        bio or updated.  As the parent_sq is always the top-level
        service_queue now, this doesn't change anything at this point.
      
      This patch doesn't introduce any behavior differences.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
      69df0ab0
    • Tejun Heo's avatar
      blk-throttle: set REQ_THROTTLED from throtl_charge_bio() and gate stats update with it · 2a0f61e6
      Tejun Heo authored
      With proper hierarchy support, a bio can be dispatched multiple times
      until it reaches the top-level service_queue and we don't want to
      update dispatch stats at each step.  They are local stats and will be
      kept local.  If recursive stats are necessary, they should be
      implemented separately and definitely not by updating counters
      recursively on each dispatch.
      
      This patch moves REQ_THROTTLED setting to throtl_charge_bio() and gate
      stats update with it so that dispatch stats are updated only on the
      first time the bio is charged to a throtl_grp, which will always be
      the throtl_grp the bio was originally queued to.
      
      This means that REQ_THROTTLED would be set even for bios which don't
      get throttled.  As we don't want bios to leave blk-throtl with the
      flag set, move REQ_THROTLLED clearing to the end of blk_throtl_bio()
      and clear if the bio is being issued directly.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
      2a0f61e6
    • Tejun Heo's avatar
      blk-throttle: implement sq_to_tg(), sq_to_td() and throtl_log() · fda6f272
      Tejun Heo authored
      Now that both throtl_data and throtl_grp embed throtl_service_queue,
      we can unify throtl_log() and throtl_log_tg().
      
      * sq_to_tg() is added.  This returns the throtl_grp a service_queue is
        embedded in.  If the service_queue is the top-level one embedded in
        throtl_data, NULL is returned.
      
      * sq_to_td() is added.  A service_queue is always associated with a
        throtl_data.  This function finds the associated td and returns it.
      
      * throtl_log() is updated to take throtl_service_queue instead of
        throtl_data.  If the service_queue is one embedded in throtl_grp, it
        prints the same header as throtl_log_tg() did.  If it's one embedded
        in throtl_data, it behaves the same as before.  This renders
        throtl_log_tg() unnecessary.  Removed.
      
      This change is necessary for hierarchy support as we're gonna be using
      the same code paths to dispatch bios to intermediate service_queues
      embedded in throtl_grps and the top-level service_queue embedded in
      throtl_data.
      
      This patch doesn't make any behavior changes.
      
      v2: throtl_log() didn't print a space after blkg path.  Updated so
          that it prints a space after throtl_grp path.  Spotted by Vivek.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
      fda6f272
    • Tejun Heo's avatar
      blk-throttle: add throtl_service_queue->parent_sq · 77216b04
      Tejun Heo authored
      To prepare for hierarchy support, this patch adds
      throtl_service_queue->service_sq which points to the arent
      service_queue.  Currently, for all service_queues embedded in
      throtl_grps, it points to throtl_data->service_queue.  As
      throtl_data->service_queue doesn't have a parent its parent_sq is set
      to NULL.
      
      There are a number of functions which take both throtl_grp *tg and
      throtl_service_queue *parent_sq.  With this patch, the parent
      service_queue can be determined from @tg and the @parent_sq arguments
      are removed.
      
      This patch doesn't make any behavior differences.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
      77216b04
    • Tejun Heo's avatar
      blk-throttle: generalize update_disptime optimization in blk_throtl_bio() · 0e9f4164
      Tejun Heo authored
      When blk_throtl_bio() wants to queue a bio to a tg (throtl_grp), it
      avoids invoking tg_update_disptime() and
      throtl_schedule_next_dispatch() if the tg already has bios queued in
      that direction.  As a new bio is appeneded after the existing ones, it
      can't change the tg's next dispatch time or the parent's dispatch
      schedule.
      
      This optimization is currently open coded in blk_throtl_bio().
      Whether the target biolist was occupied was recorded in a local
      variable and later used to skip disptime update.  This patch moves
      generalizes it so that throtl_add_bio_tg() sets a new flag
      THROTL_TG_WAS_EMPTY if the biolist was empty before the new bio was
      added.  tg_update_disptime() clears the flag automatically.
      blk_throtl_bio() is updated to simply test the flag before updating
      disptime.
      
      This patch doesn't make any functional differences now but will enable
      using the same optimization for recursive dispatch.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
      0e9f4164
    • Tejun Heo's avatar
      blk-throttle: dispatch to throtl_data->service_queue.bio_lists[] · 651930bc
      Tejun Heo authored
      throtl_service_queues will eventually form a tree which is anchored at
      throtl_data->service_queue and queue bios will climb the tree to the
      top service_queue to be executed.
      
      This patch makes the dispatch paths in blk_throtl_dispatch_work_fn()
      and blk_throtl_drain() to dispatch bios to
      throtl_data->service_queue.bio_lists[] instead of the on-stack
      bio_lists.  This will keep the final dispatch to the top level
      service_queue share the same mechanism as dispatches through the rest
      of the hierarchy.
      
      As bio's should be issued in a sleepable context,
      blk_throtl_dispatch_work_fn() transfers all dispatched bio's from the
      service_queue bio_lists[] into an onstack one before dropping
      queue_lock and issuing the bio's.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
      651930bc
    • Tejun Heo's avatar
      blk-throttle: move bio_lists[] and friends to throtl_service_queue · 73f0d49a
      Tejun Heo authored
      throtl_service_queues will eventually form a tree which is anchored at
      throtl_data->service_queue and queue bios will climb the tree to the
      top service_queue to be executed.
      
      This patch moves bio_lists[] and nr_queued[] from throtl_grp to its
      service_queue to prepare for that.  As currently only the
      throtl_data->service_queue is in use, this patch just ends up moving
      throtl_grp->bio_lists[] and ->nr_queued[] to
      throtl_grp->service_queue.bio_lists[] and ->nr_queued[] without making
      any functional differences.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
      73f0d49a
    • Tejun Heo's avatar
      blk-throttle: add throtl_grp->service_queue · 49a2f1e3
      Tejun Heo authored
      Currently, there's single service_queue per queue -
      throtl_data->service_queue.  All active throtl_grp's are queued on the
      queue and dispatched according to their limits.  To support hierarchy,
      this will be expanded such that active throtl_grp's form a tree
      anchored at throtl_data->service_queue and chained through each
      intermediate throtl_grp's service_queue.
      
      This patch adds throtl_grp->service_queue to prepare for hierarchy
      support.  The initialization function - throtl_service_queue_init() -
      is added and replaces the macro initializer.  The newly added
      tg->service_queue isn't used yet.  Following patches will do.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
      49a2f1e3
    • Tejun Heo's avatar
      blk-throttle: reorganize throtl_service_queue passed around as argument · 0049af73
      Tejun Heo authored
      throtl_service_queue will be the building block of hierarchy support
      and will form a tree.  This patch updates its usages as arguments to
      reduce confusion.
      
      * When a service queue is used as the parent role - the host of the
        rbtree - use @parent_sq instead of @sq.
      
      * For functions taking both @tg and @parent_sq, reorder them so that
        the order is (@tg, @parent_sq) not the other way around.  This makes
        the code follow the usual convention of specifying the primary
        target of the operation as the first argument.
      
      This patch doesn't make any functional differences.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
      0049af73
    • Tejun Heo's avatar
      blk-throttle: pass around throtl_service_queue instead of throtl_data · e2d57e60
      Tejun Heo authored
      throtl_service_queue will be used as the basic block to implement
      hierarchy support.  Pass around throtl_service_queue *sq instead of
      throtl_data *td in the following functions which will be used across
      multiple levels of hierarchy.
      
      * [__]throtl_enqueue/dequeue_tg()
      
      * throtl_add_bio_tg()
      
      * tg_update_disptime()
      
      * throtl_select_dispatch()
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
      e2d57e60
    • Tejun Heo's avatar
      blk-throttle: add backlink pointer from throtl_grp to throtl_data · 0f3457f6
      Tejun Heo authored
      Add throtl_grp->td so that the td (throtl_data) a given tg
      (throtl_grp) belongs to can be determined, and remove @td argument
      from functions which take both @td and @tg as the former now can be
      determined from the latter.
      
      This generally simplifies the code and removes a number of cases where
      @td is passed as an argument without being actually used.  This will
      also help hierarchy support implementation.
      
      While at it, in multi-line conditions, move the logical operators
      leading broken lines to the end of the previous line.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
      0f3457f6
    • Tejun Heo's avatar
      blk-throttle: simplify throtl_grp flag handling · 5b2c16aa
      Tejun Heo authored
      blk-throttle is still using function-defining macros to define flag
      handling functions, which went out style at least a decade ago.
      
      Just define the flag as bitmask and use direct bit operations.
      
      This patch doesn't make any functional changes.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
      5b2c16aa
    • Tejun Heo's avatar
      blk-throttle: rename throtl_rb_root to throtl_service_queue · c9e0332e
      Tejun Heo authored
      throtl_rb_root will be expanded to cover more roles for hierarchy
      support.  Rename it to throtl_service_queue and make its fields more
      descriptive.
      
      * rb		-> pending_tree
      * left		-> first_pending
      * count		-> nr_pending
      * min_disptime	-> first_pending_disptime
      
      This patch is purely cosmetic.
      
      Signed-off-by: Tejun Heo <tj@kernel.org
      Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
      c9e0332e
    • Tejun Heo's avatar
      blk-throttle: remove pointless throtl_nr_queued() optimizations · 6a525600
      Tejun Heo authored
      throtl_nr_queued() is used in several places to avoid performing
      certain operations when the throtl_data is empty.  This usually is
      useless as those paths usually aren't traveled if there's no bio
      queued.
      
      * throtl_schedule_delayed_work() skips scheduling dispatch work item
        if @td doesn't have any bios queued; however, the only case it can
        be called when @td is empty is from tg_set_conf() which isn't
        something we should be optimizing for.
      
      * throtl_schedule_next_dispatch() takes a quick exit if @td is empty;
        however, right after that it triggers BUG if the service tree is
        empty.  The two conditions are equivalent and it can just test
        @st->count for the quick exit.
      
      * blk_throtl_dispatch_work_fn() skips dispatch if @td is empty.  This
        work function isn't usually invoked when @td is empty.  The only
        possibility is from tg_set_conf() and when it happens the normal
        dispatching path can handle empty @td fine.  No need to add special
        skip path.
      
      This patch removes the above three unnecessary optimizations, which
      leave throtl_log() call in blk_throtl_dispatch_work_fn() the only user
      of throtl_nr_queued().  Remove throtl_nr_queued() and open code it in
      throtl_log().  I don't think we need td->nr_queued[] at all.  Maybe we
      can remove it later.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
      6a525600
    • Tejun Heo's avatar
      blk-throttle: relocate throtl_schedule_delayed_work() · a9131a27
      Tejun Heo authored
      Move throtl_schedule_delayed_work() above its first user so that the
      forward declaration can be removed.
      
      This patch is pure relocaiton.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
      a9131a27
    • Tejun Heo's avatar
      blk-throttle: collapse throtl_dispatch() into the work function · cb76199c
      Tejun Heo authored
      blk-throttle is about to go through major restructuring to support
      hierarchy.  Do cosmetic updates in preparation.
      
      * s/throtl_data->throtl_work/throtl_data->dispatch_work/
      
      * s/blk_throtl_work()/blk_throtl_dispatch_work_fn()/
      
      * Collapse throtl_dispatch() into blk_throtl_dispatch_work_fn()
      
      This patch is purely cosmetic.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
      cb76199c
    • Tejun Heo's avatar
      blk-throttle: remove deferred config application mechanism · 632b4493
      Tejun Heo authored
      When bps or iops configuration changes, blk-throttle records the new
      configuration and sets a flag indicating that the config has changed.
      The flag is checked in the bio dispatch path and applied.  This
      deferred config application was necessary due to limitations in blkcg
      framework, which haven't existed for quite a while now.
      
      This patch removes the deferred config application mechanism and
      applies new configurations directly from tg_set_conf(), which is
      simpler.
      
      v2: Dropped unnecessary throtl_schedule_delayed_work() call from
          tg_set_conf() as suggested by Vivek Goyal.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
      632b4493
    • Tejun Heo's avatar
      blk-throttle: remove spurious throtl_enqueue_tg() call from throtl_select_dispatch() · 2db6314c
      Tejun Heo authored
      throtl_select_dispatch() calls throtl_enqueue_tg() right after
      tg_update_disptime(), which always calls the function anyway.  The
      call is, while harmless, unnecessary.  Remove it.
      
      This patch doesn't introduce any behavior difference.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
      2db6314c
    • Tejun Heo's avatar
      blkcg: move bulk of blkcg_gq release operations to the RCU callback · 2a4fd070
      Tejun Heo authored
      Currently, when the last reference of a blkcg_gq is put, all then
      release operations sans the actual freeing happen directly in
      blkg_put().  As blkg_put() may be called under queue_lock, all
      pd_exit_fn()s may be too.  This makes it impossible for pd_exit_fn()s
      to use del_timer_sync() on timers which grab the queue_lock which is
      an irq-safe lock due to the deadlock possibility described in the
      comment on top of del_timer_sync().
      
      This can be easily avoided by perfoming the release operations in the
      RCU callback instead of directly from blkg_put().  This patch moves
      the blkcg_gq release operations to the RCU callback.
      
      As this leaves __blkg_release() with only call_rcu() invocation,
      blkg_rcu_free() is renamed to __blkg_release_rcu(), exported and
      call_rcu() invocation is now done directly from blkg_put() instead of
      going through __blkg_release() which is removed.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
      2a4fd070
    • Tejun Heo's avatar
      blkcg: invoke blkcg_policy->pd_init() after parent is linked · db613670
      Tejun Heo authored
      Currently, when creating a new blkcg_gq, each policy's pd_init_fn() is
      invoked in blkg_alloc() before the parent is linked.  This makes it
      difficult for policies to perform initializations which are dependent
      on the parent.
      
      This patch moves pd_init_fn() invocations to blkg_create() after the
      parent blkg is linked where the new blkg is fully initialized.  As
      this means that blkg_free() can't assume that pd's are initialized,
      pd_exit_fn() invocations are moved to __blkg_release().  This
      guarantees that pd_exit_fn() is also invoked with fully initialized
      blkgs with valid parent pointers.
      
      This will help implementing hierarchy support in blk-throttle.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
      db613670
    • Tejun Heo's avatar
      blkcg: implement blkg_for_each_descendant_post() · aa539cb3
      Tejun Heo authored
      This will be used by blk-throttle hierarchy support.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
      aa539cb3
    • Tejun Heo's avatar
      blkcg: move blkg_for_each_descendant_pre() to block/blk-cgroup.h · dd4a4ffc
      Tejun Heo authored
      blk-throttle hierarchy support will make use of it.  Move
      blkg_for_each_descendant_pre() from block/blk-cgroup.c to
      block/blk-cgroup.h.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
      dd4a4ffc
    • Tejun Heo's avatar
      blkcg: fix error return path in blkg_create() · 2423c9c3
      Tejun Heo authored
      In blkg_create(), after lookup of parent fails, the control jumps to
      error path with the error code encoded into @blkg.  The error path
      doesn't use @blkg for the return value.  It returns ERR_PTR(ret).
      Make lookup fail path set @ret instead of @blkg.
      
      Note that the parent lookup is guaranteed to succeed at that point and
      the condition check is purely for sanity and triggers WARN when fails.
      As such, I don't think it's necessary to mark it for -stable.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
      2423c9c3
  2. 12 May, 2013 2 commits
    • Linus Torvalds's avatar
      Linux 3.10-rc1 · f722406f
      Linus Torvalds authored
      f722406f
    • Linus Torvalds's avatar
      Merge tag 'trace-fixes-v3.10' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace · 26b840ae
      Linus Torvalds authored
      Pull tracing/kprobes update from Steven Rostedt:
       "The majority of these changes are from Masami Hiramatsu bringing
        kprobes up to par with the latest changes to ftrace (multi buffering
        and the new function probes).
      
        He also discovered and fixed some bugs in doing so.  When pulling in
        his patches, I also found a few minor bugs as well and fixed them.
      
        This also includes a compile fix for some archs that select the ring
        buffer but not tracing.
      
        I based this off of the last patch you took from me that fixed the
        merge conflict error, as that was the commit that had all the changes
        I needed for this set of changes."
      
      * tag 'trace-fixes-v3.10' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
        tracing/kprobes: Support soft-mode disabling
        tracing/kprobes: Support ftrace_event_file base multibuffer
        tracing/kprobes: Pass trace_probe directly from dispatcher
        tracing/kprobes: Increment probe hit-count even if it is used by perf
        tracing/kprobes: Use bool for retprobe checker
        ftrace: Fix function probe when more than one probe is added
        ftrace: Fix the output of enabled_functions debug file
        ftrace: Fix locking in register_ftrace_function_probe()
        tracing: Add helper function trace_create_new_event() to remove duplicate code
        tracing: Modify soft-mode only if there's no other referrer
        tracing: Indicate enabled soft-mode in enable file
        tracing/kprobes: Fix to increment return event probe hit-count
        ftrace: Cleanup regex_lock and ftrace_lock around hash updating
        ftrace, kprobes: Fix a deadlock on ftrace_regex_lock
        ftrace: Have ftrace_regex_write() return either read or error
        tracing: Return error if register_ftrace_function_probe() fails for event_enable_func()
        tracing: Don't succeed if event_enable_func did not register anything
        ring-buffer: Select IRQ_WORK
      26b840ae
  3. 11 May, 2013 4 commits
    • Linus Torvalds's avatar
      Merge tag 'stable/for-linus-3.10-rc0-tag-two' of... · 607eeb0b
      Linus Torvalds authored
      Merge tag 'stable/for-linus-3.10-rc0-tag-two' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen
      
      Pull Xen bug-fixes from Konrad Rzeszutek Wilk:
       - More fixes in the vCPU PVHVM hotplug path.
       - Add more documentation.
       - Fix various ARM related issues in the Xen generic drivers.
       - Updates in the xen-pciback driver per Bjorn's updates.
       - Mask the x2APIC feature for PV guests.
      
      * tag 'stable/for-linus-3.10-rc0-tag-two' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen:
        xen/pci: Used cached MSI-X capability offset
        xen/pci: Use PCI_MSIX_TABLE_BIR, not PCI_MSIX_FLAGS_BIRMASK
        xen: clear IRQ_NOAUTOEN and IRQ_NOREQUEST
        xen: mask x2APIC feature in PV
        xen: SWIOTLB is only used on x86
        xen/spinlock: Fix check from greater than to be also be greater or equal to.
        xen/smp/pvhvm: Don't point per_cpu(xen_vpcu, 33 and larger) to shared_info
        xen/vcpu: Document the xen_vcpu_info and xen_vcpu
        xen/vcpu/pvhvm: Fix vcpu hotplugging hanging.
      607eeb0b
    • Linus Torvalds's avatar
      Merge tag 'scsi-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi · 4c444501
      Linus Torvalds authored
      Pull second SCSI update from James "Jaj B" Bottomley:
       "This is the final round of SCSI patches for the merge window.  It
        consists mostly of driver updates (bnx2fc, ibmfc, fnic, lpfc,
        be2iscsi, pm80xx, qla4x and ipr).
      
        There's also the power management updates that complete the patches in
        Jens' tree, an iscsi refcounting problem fix from the last pull, some
        dif handling in scsi_debug fixes, a few nice code cleanups and an
        error handling busy bug fix."
      
      * tag 'scsi-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (92 commits)
        [SCSI] qla2xxx: Update firmware link in Kconfig file.
        [SCSI] iscsi class, qla4xxx: fix sess/conn refcounting when find fns are used
        [SCSI] sas: unify the pointlessly separated enums sas_dev_type and sas_device_type
        [SCSI] pm80xx: thermal, sas controller config and error handling update
        [SCSI] pm80xx: NCQ error handling changes
        [SCSI] pm80xx: WWN Modification for PM8081/88/89 controllers
        [SCSI] pm80xx: Changed module name and debug messages update
        [SCSI] pm80xx: Firmware flash memory free fix, with addition of new memory region for it
        [SCSI] pm80xx: SPC new firmware changes for device id 0x8081 alone
        [SCSI] pm80xx: Added SPCv/ve specific hardware functionalities and relevant changes in common files
        [SCSI] pm80xx: MSI-X implementation for using 64 interrupts
        [SCSI] pm80xx: Updated common functions common for SPC and SPCv/ve
        [SCSI] pm80xx: Multiple inbound/outbound queue configuration
        [SCSI] pm80xx: Added SPCv/ve specific ids, variables and modify for SPC
        [SCSI] lpfc: fix up Kconfig dependencies
        [SCSI] Handle MLQUEUE busy response in scsi_send_eh_cmnd
        [SCSI] sd: change to auto suspend mode
        [SCSI] sd: use REQ_PM in sd's runtime suspend operation
        [SCSI] qla4xxx: Fix iocb_cnt calculation in qla4xxx_send_mbox_iocb()
        [SCSI] ufs: Correct the expected data transfersize
        ...
      4c444501
    • Linus Torvalds's avatar
      Merge branch 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux · ac4e0109
      Linus Torvalds authored
      Pull idle update from Len Brown:
       "Add support for new Haswell-ULT CPU idle power states"
      
      * 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux:
        intel_idle: initial C8, C9, C10 support
        tools/power turbostat: display C8, C9, C10 residency
      ac4e0109
    • Linus Torvalds's avatar
      Merge git://git.infradead.org/users/eparis/audit · c4cc75c3
      Linus Torvalds authored
      Pull audit changes from Eric Paris:
       "Al used to send pull requests every couple of years but he told me to
        just start pushing them to you directly.
      
        Our touching outside of core audit code is pretty straight forward.  A
        couple of interface changes which hit net/.  A simple argument bug
        calling audit functions in namei.c and the removal of some assembly
        branch prediction code on ppc"
      
      * git://git.infradead.org/users/eparis/audit: (31 commits)
        audit: fix message spacing printing auid
        Revert "audit: move kaudit thread start from auditd registration to kaudit init"
        audit: vfs: fix audit_inode call in O_CREAT case of do_last
        audit: Make testing for a valid loginuid explicit.
        audit: fix event coverage of AUDIT_ANOM_LINK
        audit: use spin_lock in audit_receive_msg to process tty logging
        audit: do not needlessly take a lock in tty_audit_exit
        audit: do not needlessly take a spinlock in copy_signal
        audit: add an option to control logging of passwords with pam_tty_audit
        audit: use spin_lock_irqsave/restore in audit tty code
        helper for some session id stuff
        audit: use a consistent audit helper to log lsm information
        audit: push loginuid and sessionid processing down
        audit: stop pushing loginid, uid, sessionid as arguments
        audit: remove the old depricated kernel interface
        audit: make validity checking generic
        audit: allow checking the type of audit message in the user filter
        audit: fix build break when AUDIT_DEBUG == 2
        audit: remove duplicate export of audit_enabled
        Audit: do not print error when LSMs disabled
        ...
      c4cc75c3
  4. 10 May, 2013 1 commit