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  1. 13 8月, 2014 1 次提交
    • P
      locking: Remove deprecated smp_mb__() barriers · 2e39465a
      由 Peter Zijlstra 提交于 
      Its been a while and there are no in-tree users left, so remove the
deprecated barriers.
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
Cc: Chen, Gong <gong.chen@linux.intel.com>
Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: Joe Perches <joe@perches.com>
Cc: John Sullivan <jsrhbz@kanargh.force9.co.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      2e39465a
  3. 28 7月, 2014 3 次提交
  5. 16 7月, 2014 3 次提交
  7. 15 7月, 2014 1 次提交
    • T
      cgroup: rename cgroup_subsys->base_cftypes to ->legacy_cftypes · 5577964e
      由 Tejun Heo 提交于 
      Currently, cgroup_subsys->base_cftypes is used for both the unified
default hierarchy and legacy ones and subsystems can mark each file
with either CFTYPE_ONLY_ON_DFL or CFTYPE_INSANE if it has to appear
only on one of them.  This is quite hairy and error-prone.  Also, we
may end up exposing interface files to the default hierarchy without
thinking it through.

cgroup_subsys will grow two separate cftype arrays and apply each only
on the hierarchies of the matching type.  This will allow organizing
cftypes in a lot clearer way and encourage subsystems to scrutinize
the interface which is being exposed in the new default hierarchy.

In preparation, this patch renames cgroup_subsys->base_cftypes to
cgroup_subsys->legacy_cftypes.  This patch is pure rename.
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NNeil Horman <nhorman@tuxdriver.com>
Acked-by: NLi Zefan <lizefan@huawei.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Aristeu Rozanski <aris@redhat.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
      5577964e
  9. 05 7月, 2014 3 次提交
  11. 24 6月, 2014 1 次提交
    • P
      rcu: Reduce overhead of cond_resched() checks for RCU · 4a81e832
      由 Paul E. McKenney 提交于 
      Commit ac1bea85 (Make cond_resched() report RCU quiescent states)
fixed a problem where a CPU looping in the kernel with but one runnable
task would give RCU CPU stall warnings, even if the in-kernel loop
contained cond_resched() calls.  Unfortunately, in so doing, it introduced
performance regressions in Anton Blanchard's will-it-scale "open1" test.
The problem appears to be not so much the increased cond_resched() path
length as an increase in the rate at which grace periods complete, which
increased per-update grace-period overhead.

This commit takes a different approach to fixing this bug, mainly by
moving the RCU-visible quiescent state from cond_resched() to
rcu_note_context_switch(), and by further reducing the check to a
simple non-zero test of a single per-CPU variable.  However, this
approach requires that the force-quiescent-state processing send
resched IPIs to the offending CPUs.  These will be sent only once
the grace period has reached an age specified by the boot/sysfs
parameter rcutree.jiffies_till_sched_qs, or once the grace period
reaches an age halfway to the point at which RCU CPU stall warnings
will be emitted, whichever comes first.
Reported-by: NDave Hansen <dave.hansen@intel.com>
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Christoph Lameter <cl@gentwo.org>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Reviewed-by: NJosh Triplett <josh@joshtriplett.org>
[ paulmck: Made rcu_momentary_dyntick_idle() as suggested by the
  ktest build robot.  Also fixed smp_mb() comment as noted by
  Oleg Nesterov. ]

Merge with e552592e (Reduce overhead of cond_resched() checks for RCU)
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
      4a81e832
  13. 16 6月, 2014 3 次提交
    • F
      nohz: Use IPI implicit full barrier against rq->nr_running r/w · 3882ec64
      由 Frederic Weisbecker 提交于 
      A full dynticks CPU is allowed to stop its tick when a single task runs.
Meanwhile when a new task gets enqueued, the CPU must be notified so that
it can restart its tick to maintain local fairness and other accounting
details.

This notification is performed by way of an IPI. Then when the target
receives the IPI, we expect it to see the new value of rq->nr_running.

Hence the following ordering scenario:

   CPU 0                   CPU 1

   write rq->running       get IPI
   smp_wmb()               smp_rmb()
   send IPI                read rq->nr_running

But Paul Mckenney says that nowadays IPIs imply a full barrier on
all architectures. So we can safely remove this pair and rely on the
implicit barriers that come along IPI send/receive. Lets
just comment on this new assumption.
Acked-by: NPeter Zijlstra <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
      3882ec64
    • F
      nohz: Use nohz own full kick on 2nd task enqueue · fd2ac4f4
      由 Frederic Weisbecker 提交于 
      Now that we have a nohz full remote kick based on irq work, lets use
it to notify a CPU that it's exiting single task mode.

This unbloats a bit the scheduler IPI that the nohz code was abusing
for its cool "callable anywhere/anytime" properties.
Acked-by: NPeter Zijlstra <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
      fd2ac4f4
    • F
      nohz: Switch to nohz full remote kick on timer enqueue · 53c5fa16
      由 Frederic Weisbecker 提交于 
      When a new timer is enqueued on a full dynticks target, that CPU must
re-evaluate the next tick to handle the timer correctly.

This is currently performed through the scheduler IPI. Meanwhile this
happens at the cost of off-topic workarounds in that fast path to make
it call irq_exit().

As we plan to remove this hack off the scheduler IPI, lets use
the nohz full kick instead. Pretty much any IPI fits for that job
as long at it calls irq_exit(). The nohz full kick just happens to be
handy and readily available here.

If it happens to be too much an overkill in the future, we can still
turn that timer kick into an empty IPI.
Acked-by: NPeter Zijlstra <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
      53c5fa16
  15. 05 6月, 2014 11 次提交
  17. 22 5月, 2014 12 次提交
  19. 17 5月, 2014 1 次提交
    • T
      cgroup: remove css_parent() · 5c9d535b
      由 Tejun Heo 提交于 
      cgroup in general is moving towards using cgroup_subsys_state as the
fundamental structural component and css_parent() was introduced to
convert from using cgroup->parent to css->parent.  It was quite some
time ago and we're moving forward with making css more prominent.

This patch drops the trivial wrapper css_parent() and let the users
dereference css->parent.  While at it, explicitly mark fields of css
which are public and immutable.

v2: New usage from device_cgroup.c converted.
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NMichal Hocko <mhocko@suse.cz>
Acked-by: NNeil Horman <nhorman@tuxdriver.com>
Acked-by: N"David S. Miller" <davem@davemloft.net>
Acked-by: NLi Zefan <lizefan@huawei.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Johannes Weiner <hannes@cmpxchg.org>
      5c9d535b
  21. 15 5月, 2014 1 次提交
    • P
      sched,rcu: Make cond_resched() report RCU quiescent states · ac1bea85
      由 Paul E. McKenney 提交于 
      Given a CPU running a loop containing cond_resched(), with no
other tasks runnable on that CPU, RCU will eventually report RCU
CPU stall warnings due to lack of quiescent states.  Fortunately,
every call to cond_resched() is a perfectly good quiescent state.
Unfortunately, invoking rcu_note_context_switch() is a bit heavyweight
for cond_resched(), especially given the need to disable preemption,
and, for RCU-preempt, interrupts as well.

This commit therefore maintains a per-CPU counter that causes
cond_resched(), cond_resched_lock(), and cond_resched_softirq() to call
rcu_note_context_switch(), but only about once per 256 invocations.
This ratio was chosen in keeping with the relative time constants of
RCU grace periods.
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: NJosh Triplett <josh@joshtriplett.org>
      ac1bea85