Commit Graph

2007 Commits

Author SHA1 Message Date
Vincent Guittot 9059393e4e sched/fair: Use reweight_entity() for set_user_nice()
Now that we directly change load_avg and propagate that change into
the sums, sys_nice() and co should do the same, otherwise its possible
to confuse load accounting when we migrate near the weight change.

Fixes-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
[ Added changelog, fixed the call condition. ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/20170517095045.GA8420@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-09-29 19:35:14 +02:00
Peter Zijlstra 840c5abca4 sched/fair: More accurate reweight_entity()
When a (group) entity changes it's weight we should instantly change
its load_avg and propagate that change into the sums it is part of.
Because we use these values to predict future behaviour and are not
interested in its historical value.

Without this change, the change in load would need to propagate
through the average, by which time it could again have changed etc..
always chasing itself.

With this change, the cfs_rq load_avg sum will more accurately reflect
the current runnable and expected return of blocked load.

Reported-by: Paul Turner <pjt@google.com>
[josef: compile fix !SMP || !FAIR_GROUP]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-09-29 19:35:14 +02:00
Peter Zijlstra 8d5b9025f9 sched/fair: Introduce {en,de}queue_load_avg()
Analogous to the existing {en,de}queue_runnable_load_avg() add helpers
for {en,de}queue_load_avg(). More users will follow.

Includes some code movement to avoid fwd declarations.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-09-29 19:35:13 +02:00
Peter Zijlstra b5b3e35f41 sched/fair: Rename {en,de}queue_entity_load_avg()
Since they're now purely about runnable_load, rename them.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-09-29 19:35:13 +02:00
Peter Zijlstra b382a531b9 sched/fair: Move enqueue migrate handling
Move the entity migrate handling from enqueue_entity_load_avg() to
update_load_avg(). This has two benefits:

 - {en,de}queue_entity_load_avg() will become purely about managing
   runnable_load

 - we can avoid a double update_tg_load_avg() and reduce pressure on
   the global tg->shares cacheline

The reason we do this is so that we can change update_cfs_shares() to
change both weight and (future) runnable_weight. For this to work we
need to have the cfs_rq averages up-to-date (which means having done
the attach), but we need the cfs_rq->avg.runnable_avg to not yet
include the se's contribution (since se->on_rq == 0).

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-09-29 19:35:12 +02:00
Peter Zijlstra 88c0616ee7 sched/fair: Change update_load_avg() arguments
Most call sites of update_load_avg() already have cfs_rq_of(se)
available, pass it down instead of recomputing it.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-09-29 19:35:12 +02:00
Peter Zijlstra c7b5021681 sched/fair: Remove se->load.weight from se->avg.load_sum
Remove the load from the load_sum for sched_entities, basically
turning load_sum into runnable_sum.  This prepares for better
reweighting of group entities.

Since we now have different rules for computing load_avg, split
___update_load_avg() into two parts, ___update_load_sum() and
___update_load_avg().

So for se:

  ___update_load_sum(.weight = 1)
  ___upate_load_avg(.weight = se->load.weight)

and for cfs_rq:

  ___update_load_sum(.weight = cfs_rq->load.weight)
  ___upate_load_avg(.weight = 1)

Since the primary consumable is load_avg, most things will not be
affected. Only those few sites that initialize/modify load_sum need
attention.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-09-29 19:35:12 +02:00
Peter Zijlstra 3d4b60d3e3 sched/fair: Cure calc_cfs_shares() vs. reweight_entity()
Vincent reported that when running in a cgroup, his root
cfs_rq->avg.load_avg dropped to 0 on task idle.

This is because reweight_entity() will now immediately propagate the
weight change of the group entity to its cfs_rq, and as it happens,
our approxmation (5) for calc_cfs_shares() results in 0 when the group
is idle.

Avoid this by using the correct (3) as a lower bound on (5). This way
the empty cgroup will slowly decay instead of instantly drop to 0.

Reported-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-09-29 19:35:11 +02:00
Peter Zijlstra cef27403cb sched/fair: Add comment to calc_cfs_shares()
Explain the magic equation in calc_cfs_shares() a bit better.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-09-29 19:35:11 +02:00
Peter Zijlstra 7c80cfc99b sched/fair: Clean up calc_cfs_shares()
For consistencies sake, we should have only a single reading of tg->shares.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-09-29 19:35:10 +02:00
Peter Zijlstra 5d68cc95fb sched/debug: Ignore TASK_IDLE for SysRq-W
Markus reported that tasks in TASK_IDLE state are reported by SysRq-W,
which results in undesirable clutter.

Reported-by: Markus Trippelsdorf <markus@trippelsdorf.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-09-29 11:02:57 +02:00
Peter Zijlstra 65d5dc47fe sched/debug: Remove unused variable
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-09-29 10:09:09 +02:00
Tim Chen 11a19c7b09 sched/wait: Introduce wakeup boomark in wake_up_page_bit
Now that we have added breaks in the wait queue scan and allow bookmark
on scan position, we put this logic in the wake_up_page_bit function.

We can have very long page wait list in large system where multiple
pages share the same wait list. We break the wake up walk here to allow
other cpus a chance to access the list, and not to disable the interrupts
when traversing the list for too long.  This reduces the interrupt and
rescheduling latency, and excessive page wait queue lock hold time.

[ v2: Remove bookmark_wake_function ]

Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-09-14 09:56:18 -07:00
Tim Chen 2554db9165 sched/wait: Break up long wake list walk
We encountered workloads that have very long wake up list on large
systems. A waker takes a long time to traverse the entire wake list and
execute all the wake functions.

We saw page wait list that are up to 3700+ entries long in tests of
large 4 and 8 socket systems. It took 0.8 sec to traverse such list
during wake up. Any other CPU that contends for the list spin lock will
spin for a long time. It is a result of the numa balancing migration of
hot pages that are shared by many threads.

Multiple CPUs waking are queued up behind the lock, and the last one
queued has to wait until all CPUs did all the wakeups.

The page wait list is traversed with interrupt disabled, which caused
various problems. This was the original cause that triggered the NMI
watch dog timer in: https://patchwork.kernel.org/patch/9800303/ . Only
extending the NMI watch dog timer there helped.

This patch bookmarks the waker's scan position in wake list and break
the wake up walk, to allow access to the list before the waker resume
its walk down the rest of the wait list. It lowers the interrupt and
rescheduling latency.

This patch also provides a performance boost when combined with the next
patch to break up page wakeup list walk. We saw 22% improvement in the
will-it-scale file pread2 test on a Xeon Phi system running 256 threads.

[ v2: Merged in Linus' changes to remove the bookmark_wake_function, and
  simply access to flags. ]

Reported-by: Kan Liang <kan.liang@intel.com>
Tested-by: Kan Liang <kan.liang@intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-09-14 09:56:17 -07:00
Linus Torvalds ec846ecd63 Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Ingo Molnar:
 "Three CPU hotplug related fixes and a debugging improvement"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/debug: Add debugfs knob for "sched_debug"
  sched/core: WARN() when migrating to an offline CPU
  sched/fair: Plug hole between hotplug and active_load_balance()
  sched/fair: Avoid newidle balance for !active CPUs
2017-09-13 12:22:32 -07:00
Linus Torvalds 040b9d7ccf Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Ingo Molnar:
 "Three fixes:

   - fix a suspend/resume cpusets bug

   - fix a !CONFIG_NUMA_BALANCING bug

   - fix a kerneldoc warning"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/fair: Fix nuisance kernel-doc warning
  sched/cpuset/pm: Fix cpuset vs. suspend-resume bugs
  sched/fair: Fix wake_affine_llc() balancing rules
2017-09-12 11:30:56 -07:00
Peter Zijlstra 9469eb01db sched/debug: Add debugfs knob for "sched_debug"
I'm forever late for editing my kernel cmdline, add a runtime knob to
disable the "sched_debug" thing.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170907150614.142924283@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-09-12 17:41:04 +02:00
Peter Zijlstra 4ff9083b8a sched/core: WARN() when migrating to an offline CPU
Migrating tasks to offline CPUs is a pretty big fail, warn about it.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170907150614.094206976@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-09-12 17:41:04 +02:00
Peter Zijlstra edd8e41d2e sched/fair: Plug hole between hotplug and active_load_balance()
The load balancer applies cpu_active_mask to whatever sched_domains it
finds, however in the case of active_balance there is a hole between
setting rq->{active_balance,push_cpu} and running the stop_machine
work doing the actual migration.

The @push_cpu can go offline in this window, which would result in us
moving a task onto a dead cpu, which is a fairly bad thing.

Double check the active mask before the stop work does the migration.

  CPU0					CPU1

  <SoftIRQ>
					stop_machine(takedown_cpu)
    load_balance()			cpu_stopper_thread()
      ...				  work = multi_cpu_stop
      stop_one_cpu_nowait(		    /* wait for CPU0 */
	.func = active_load_balance_cpu_stop
      );
  </SoftIRQ>

  cpu_stopper_thread()
    work = multi_cpu_stop
      /* sync with CPU1 */
					    take_cpu_down()
					<idle>
					  play_dead();

    work = active_load_balance_cpu_stop
      set_task_cpu(p, CPU1); /* oops!! */

Reported-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20170907150614.044460912@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-09-12 17:41:04 +02:00
Peter Zijlstra 2800486ee3 sched/fair: Avoid newidle balance for !active CPUs
On CPU hot unplug, when parking the last kthread we'll try and
schedule into idle to kill the CPU. This last schedule can (and does)
trigger newidle balance because at this point the sched domains are
still up because of commit:

  77d1dfda0e ("sched/topology, cpuset: Avoid spurious/wrong domain rebuilds")

Obviously pulling tasks to an already offline CPU is a bad idea, and
all balancing operations _should_ be subject to cpu_active_mask, make
it so.

Reported-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Fixes: 77d1dfda0e ("sched/topology, cpuset: Avoid spurious/wrong domain rebuilds")
Link: http://lkml.kernel.org/r/20170907150613.994135806@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-09-12 17:41:03 +02:00
Randy Dunlap 46123355af sched/fair: Fix nuisance kernel-doc warning
Work around kernel-doc warning ('*' in Sphinx doc means "emphasis"):

  ../kernel/sched/fair.c:7584: WARNING: Inline emphasis start-string without end-string.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/f18b30f9-6251-6d86-9d44-16501e386891@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-09-11 08:13:22 +02:00
Davidlohr Bueso 2161573ecd sched/deadline: replace earliest dl and rq leftmost caching
... with the generic rbtree flavor instead. No changes
in semantics whatsoever.

Link: http://lkml.kernel.org/r/20170719014603.19029-9-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-09-08 18:26:49 -07:00
Davidlohr Bueso bfb068892d sched/fair: replace cfs_rq->rb_leftmost
... with the generic rbtree flavor instead. No changes
in semantics whatsoever.

Link: http://lkml.kernel.org/r/20170719014603.19029-8-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-09-08 18:26:48 -07:00
Alexey Dobriyan 9b130ad5bb treewide: make "nr_cpu_ids" unsigned
First, number of CPUs can't be negative number.

Second, different signnnedness leads to suboptimal code in the following
cases:

1)
	kmalloc(nr_cpu_ids * sizeof(X));

"int" has to be sign extended to size_t.

2)
	while (loff_t *pos < nr_cpu_ids)

MOVSXD is 1 byte longed than the same MOV.

Other cases exist as well. Basically compiler is told that nr_cpu_ids
can't be negative which can't be deduced if it is "int".

Code savings on allyesconfig kernel: -3KB

	add/remove: 0/0 grow/shrink: 25/264 up/down: 261/-3631 (-3370)
	function                                     old     new   delta
	coretemp_cpu_online                          450     512     +62
	rcu_init_one                                1234    1272     +38
	pci_device_probe                             374     399     +25

				...

	pgdat_reclaimable_pages                      628     556     -72
	select_fallback_rq                           446     369     -77
	task_numa_find_cpu                          1923    1807    -116

Link: http://lkml.kernel.org/r/20170819114959.GA30580@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-09-08 18:26:48 -07:00
Peter Zijlstra 50e7663233 sched/cpuset/pm: Fix cpuset vs. suspend-resume bugs
Cpusets vs. suspend-resume is _completely_ broken. And it got noticed
because it now resulted in non-cpuset usage breaking too.

On suspend cpuset_cpu_inactive() doesn't call into
cpuset_update_active_cpus() because it doesn't want to move tasks about,
there is no need, all tasks are frozen and won't run again until after
we've resumed everything.

But this means that when we finally do call into
cpuset_update_active_cpus() after resuming the last frozen cpu in
cpuset_cpu_active(), the top_cpuset will not have any difference with
the cpu_active_mask and this it will not in fact do _anything_.

So the cpuset configuration will not be restored. This was largely
hidden because we would unconditionally create identity domains and
mobile users would not in fact use cpusets much. And servers what do use
cpusets tend to not suspend-resume much.

An addition problem is that we'd not in fact wait for the cpuset work to
finish before resuming the tasks, allowing spurious migrations outside
of the specified domains.

Fix the rebuild by introducing cpuset_force_rebuild() and fix the
ordering with cpuset_wait_for_hotplug().

Reported-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <stable@vger.kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: deb7aa308e ("cpuset: reorganize CPU / memory hotplug handling")
Link: http://lkml.kernel.org/r/20170907091338.orwxrqkbfkki3c24@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-09-07 11:45:21 +02:00
Peter Zijlstra a731ebe6f1 sched/fair: Fix wake_affine_llc() balancing rules
Chris Wilson reported that the SMT balance rules got the +1 on the
wrong side, resulting in a bias towards the current LLC; which the
load-balancer would then try and undo.

Reported-by: Chris Wilson <chris@chris-wilson.co.uk>
Tested-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Fixes: 90001d67be ("sched/fair: Fix wake_affine() for !NUMA_BALANCING")
Link: http://lkml.kernel.org/r/20170906105131.gqjmaextmn3u6tj2@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-09-07 09:29:31 +02:00
Linus Torvalds 439644096c Power management updates for v4.14-rc1
- Drop the P-state selection algorithm based on a PID controller
    from intel_pstate and make it use the same P-state selection
    method (based on the CPU load) for all types of systems in the
    active mode (Rafael Wysocki, Srinivas Pandruvada).
 
  - Rework the cpufreq core and governors to make it possible to
    take cross-CPU utilization updates into account and modify the
    schedutil governor to actually do so (Viresh Kumar).
 
  - Clean up the handling of transition latency information in the
    cpufreq core and untangle it from the information on which drivers
    cannot do dynamic frequency switching (Viresh Kumar).
 
  - Add support for new SoCs (MT2701/MT7623 and MT7622) to the
    mediatek cpufreq driver and update its DT bindings (Sean Wang).
 
  - Modify the cpufreq dt-platdev driver to autimatically create
    cpufreq devices for the new (v2) Operating Performance Points
    (OPP) DT bindings and update its whitelist of supported systems
    (Viresh Kumar, Shubhrajyoti Datta, Marc Gonzalez, Khiem Nguyen,
    Finley Xiao).
 
  - Add support for Ux500 to the cpufreq-dt driver and drop the
    obsolete dbx500 cpufreq driver (Linus Walleij, Arnd Bergmann).
 
  - Add new SoC (R8A7795) support to the cpufreq rcar driver (Khiem
    Nguyen).
 
  - Fix and clean up assorted issues in the cpufreq drivers and core
    (Arvind Yadav, Christophe Jaillet, Colin Ian King, Gustavo Silva,
    Julia Lawall, Leonard Crestez, Rob Herring, Sudeep Holla).
 
  - Update the IO-wait boost handling in the schedutil governor to
    make it less aggressive (Joel Fernandes).
 
  - Rework system suspend diagnostics to make it print fewer messages
    to the kernel log by default, add a sysfs knob to allow more
    suspend-related messages to be printed and add Low Power S0 Idle
    constraints checks to the ACPI suspend-to-idle code (Rafael
    Wysocki, Srinivas Pandruvada).
 
  - Prefer suspend-to-idle over S3 on ACPI-based systems with the
    ACPI_FADT_LOW_POWER_S0 flag set and the Low Power Idle S0 _DSM
    interface present in the ACPI tables (Rafael Wysocki).
 
  - Update documentation related to system sleep and rename a number
    of items in the code to make it cleare that they are related to
    suspend-to-idle (Rafael Wysocki).
 
  - Export a variable allowing device drivers to check the target
    system sleep state from the core system suspend code (Florian
    Fainelli).
 
  - Clean up the cpuidle subsystem to handle the polling state on
    x86 in a more straightforward way and to use %pOF instead of
    full_name (Rafael Wysocki, Rob Herring).
 
  - Update the devfreq framework to fix and clean up a few minor
    issues (Chanwoo Choi, Rob Herring).
 
  - Extend diagnostics in the generic power domains (genpd) framework
    and clean it up slightly (Thara Gopinath, Rob Herring).
 
  - Fix and clean up a couple of issues in the operating performance
    points (OPP) framework (Viresh Kumar, Waldemar Rymarkiewicz).
 
  - Add support for RV1108 to the rockchip-io Adaptive Voltage Scaling
    (AVS) driver (David Wu).
 
  - Fix the usage of notifiers in CPU power management on some
    platforms (Alex Shi).
 
  - Update the pm-graph system suspend/hibernation and boot profiling
    utility (Todd Brandt).
 
  - Make it possible to run the cpupower utility without CPU0 (Prarit
    Bhargava).
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Merge tag 'pm-4.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull power management updates from Rafael Wysocki:
 "This time (again) cpufreq gets the majority of changes which mostly
  are driver updates (including a major consolidation of intel_pstate),
  some schedutil governor modifications and core cleanups.

  There also are some changes in the system suspend area, mostly related
  to diagnostics and debug messages plus some renames of things related
  to suspend-to-idle. One major change here is that suspend-to-idle is
  now going to be preferred over S3 on systems where the ACPI tables
  indicate to do so and provide requsite support (the Low Power Idle S0
  _DSM in particular). The system sleep documentation and the tools
  related to it are updated too.

  The rest is a few cpuidle changes (nothing major), devfreq updates,
  generic power domains (genpd) framework updates and a few assorted
  modifications elsewhere.

  Specifics:

   - Drop the P-state selection algorithm based on a PID controller from
     intel_pstate and make it use the same P-state selection method
     (based on the CPU load) for all types of systems in the active mode
     (Rafael Wysocki, Srinivas Pandruvada).

   - Rework the cpufreq core and governors to make it possible to take
     cross-CPU utilization updates into account and modify the schedutil
     governor to actually do so (Viresh Kumar).

   - Clean up the handling of transition latency information in the
     cpufreq core and untangle it from the information on which drivers
     cannot do dynamic frequency switching (Viresh Kumar).

   - Add support for new SoCs (MT2701/MT7623 and MT7622) to the mediatek
     cpufreq driver and update its DT bindings (Sean Wang).

   - Modify the cpufreq dt-platdev driver to autimatically create
     cpufreq devices for the new (v2) Operating Performance Points (OPP)
     DT bindings and update its whitelist of supported systems (Viresh
     Kumar, Shubhrajyoti Datta, Marc Gonzalez, Khiem Nguyen, Finley
     Xiao).

   - Add support for Ux500 to the cpufreq-dt driver and drop the
     obsolete dbx500 cpufreq driver (Linus Walleij, Arnd Bergmann).

   - Add new SoC (R8A7795) support to the cpufreq rcar driver (Khiem
     Nguyen).

   - Fix and clean up assorted issues in the cpufreq drivers and core
     (Arvind Yadav, Christophe Jaillet, Colin Ian King, Gustavo Silva,
     Julia Lawall, Leonard Crestez, Rob Herring, Sudeep Holla).

   - Update the IO-wait boost handling in the schedutil governor to make
     it less aggressive (Joel Fernandes).

   - Rework system suspend diagnostics to make it print fewer messages
     to the kernel log by default, add a sysfs knob to allow more
     suspend-related messages to be printed and add Low Power S0 Idle
     constraints checks to the ACPI suspend-to-idle code (Rafael
     Wysocki, Srinivas Pandruvada).

   - Prefer suspend-to-idle over S3 on ACPI-based systems with the
     ACPI_FADT_LOW_POWER_S0 flag set and the Low Power Idle S0 _DSM
     interface present in the ACPI tables (Rafael Wysocki).

   - Update documentation related to system sleep and rename a number of
     items in the code to make it cleare that they are related to
     suspend-to-idle (Rafael Wysocki).

   - Export a variable allowing device drivers to check the target
     system sleep state from the core system suspend code (Florian
     Fainelli).

   - Clean up the cpuidle subsystem to handle the polling state on x86
     in a more straightforward way and to use %pOF instead of full_name
     (Rafael Wysocki, Rob Herring).

   - Update the devfreq framework to fix and clean up a few minor issues
     (Chanwoo Choi, Rob Herring).

   - Extend diagnostics in the generic power domains (genpd) framework
     and clean it up slightly (Thara Gopinath, Rob Herring).

   - Fix and clean up a couple of issues in the operating performance
     points (OPP) framework (Viresh Kumar, Waldemar Rymarkiewicz).

   - Add support for RV1108 to the rockchip-io Adaptive Voltage Scaling
     (AVS) driver (David Wu).

   - Fix the usage of notifiers in CPU power management on some
     platforms (Alex Shi).

   - Update the pm-graph system suspend/hibernation and boot profiling
     utility (Todd Brandt).

   - Make it possible to run the cpupower utility without CPU0 (Prarit
     Bhargava)"

* tag 'pm-4.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (87 commits)
  cpuidle: Make drivers initialize polling state
  cpuidle: Move polling state initialization code to separate file
  cpuidle: Eliminate the CPUIDLE_DRIVER_STATE_START symbol
  cpufreq: imx6q: Fix imx6sx low frequency support
  cpufreq: speedstep-lib: make several arrays static, makes code smaller
  PM: docs: Delete the obsolete states.txt document
  PM: docs: Describe high-level PM strategies and sleep states
  PM / devfreq: Fix memory leak when fail to register device
  PM / devfreq: Add dependency on PM_OPP
  PM / devfreq: Move private devfreq_update_stats() into devfreq
  PM / devfreq: Convert to using %pOF instead of full_name
  PM / AVS: rockchip-io: add io selectors and supplies for RV1108
  cpufreq: ti: Fix 'of_node_put' being called twice in error handling path
  cpufreq: dt-platdev: Drop few entries from whitelist
  cpufreq: dt-platdev: Automatically create cpufreq device with OPP v2
  ARM: ux500: don't select CPUFREQ_DT
  cpuidle: Convert to using %pOF instead of full_name
  cpufreq: Convert to using %pOF instead of full_name
  PM / Domains: Convert to using %pOF instead of full_name
  cpufreq: Cap the default transition delay value to 10 ms
  ...
2017-09-05 12:19:08 -07:00
Linus Torvalds 5f82e71a00 Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking updates from Ingo Molnar:

 - Add 'cross-release' support to lockdep, which allows APIs like
   completions, where it's not the 'owner' who releases the lock, to be
   tracked. It's all activated automatically under
   CONFIG_PROVE_LOCKING=y.

 - Clean up (restructure) the x86 atomics op implementation to be more
   readable, in preparation of KASAN annotations. (Dmitry Vyukov)

 - Fix static keys (Paolo Bonzini)

 - Add killable versions of down_read() et al (Kirill Tkhai)

 - Rework and fix jump_label locking (Marc Zyngier, Paolo Bonzini)

 - Rework (and fix) tlb_flush_pending() barriers (Peter Zijlstra)

 - Remove smp_mb__before_spinlock() and convert its usages, introduce
   smp_mb__after_spinlock() (Peter Zijlstra)

* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (56 commits)
  locking/lockdep/selftests: Fix mixed read-write ABBA tests
  sched/completion: Avoid unnecessary stack allocation for COMPLETION_INITIALIZER_ONSTACK()
  acpi/nfit: Fix COMPLETION_INITIALIZER_ONSTACK() abuse
  locking/pvqspinlock: Relax cmpxchg's to improve performance on some architectures
  smp: Avoid using two cache lines for struct call_single_data
  locking/lockdep: Untangle xhlock history save/restore from task independence
  locking/refcounts, x86/asm: Disable CONFIG_ARCH_HAS_REFCOUNT for the time being
  futex: Remove duplicated code and fix undefined behaviour
  Documentation/locking/atomic: Finish the document...
  locking/lockdep: Fix workqueue crossrelease annotation
  workqueue/lockdep: 'Fix' flush_work() annotation
  locking/lockdep/selftests: Add mixed read-write ABBA tests
  mm, locking/barriers: Clarify tlb_flush_pending() barriers
  locking/lockdep: Make CONFIG_LOCKDEP_CROSSRELEASE and CONFIG_LOCKDEP_COMPLETIONS truly non-interactive
  locking/lockdep: Explicitly initialize wq_barrier::done::map
  locking/lockdep: Rename CONFIG_LOCKDEP_COMPLETE to CONFIG_LOCKDEP_COMPLETIONS
  locking/lockdep: Reword title of LOCKDEP_CROSSRELEASE config
  locking/lockdep: Make CONFIG_LOCKDEP_CROSSRELEASE part of CONFIG_PROVE_LOCKING
  locking/refcounts, x86/asm: Implement fast refcount overflow protection
  locking/lockdep: Fix the rollback and overwrite detection logic in crossrelease
  ...
2017-09-04 11:52:29 -07:00
Linus Torvalds f213a6c84c Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
 "The main changes in this cycle were:

   - fix affine wakeups (Peter Zijlstra)

   - improve CPU onlining (and general bootup) scalability on systems
     with ridiculous number (thousands) of CPUs (Peter Zijlstra)

   - sched/numa updates (Rik van Riel)

   - sched/deadline updates (Byungchul Park)

   - sched/cpufreq enhancements and related cleanups (Viresh Kumar)

   - sched/debug enhancements (Xie XiuQi)

   - various fixes"

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (27 commits)
  sched/debug: Optimize sched_domain sysctl generation
  sched/topology: Avoid pointless rebuild
  sched/topology, cpuset: Avoid spurious/wrong domain rebuilds
  sched/topology: Improve comments
  sched/topology: Fix memory leak in __sdt_alloc()
  sched/completion: Document that reinit_completion() must be called after complete_all()
  sched/autogroup: Fix error reporting printk text in autogroup_create()
  sched/fair: Fix wake_affine() for !NUMA_BALANCING
  sched/debug: Intruduce task_state_to_char() helper function
  sched/debug: Show task state in /proc/sched_debug
  sched/debug: Use task_pid_nr_ns in /proc/$pid/sched
  sched/core: Remove unnecessary initialization init_idle_bootup_task()
  sched/deadline: Change return value of cpudl_find()
  sched/deadline: Make find_later_rq() choose a closer CPU in topology
  sched/numa: Scale scan period with tasks in group and shared/private
  sched/numa: Slow down scan rate if shared faults dominate
  sched/pelt: Fix false running accounting
  sched: Mark pick_next_task_dl() and build_sched_domain() as static
  sched/cpupri: Don't re-initialize 'struct cpupri'
  sched/deadline: Don't re-initialize 'struct cpudl'
  ...
2017-09-04 09:10:24 -07:00
Linus Torvalds 0081a0ce80 Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull RCU updates from Ingo Molnad:
 "The main RCU related changes in this cycle were:

   - Removal of spin_unlock_wait()
   - SRCU updates
   - RCU torture-test updates
   - RCU Documentation updates
   - Extend the sys_membarrier() ABI with the MEMBARRIER_CMD_PRIVATE_EXPEDITED variant
   - Miscellaneous RCU fixes
   - CPU-hotplug fixes"

* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (63 commits)
  arch: Remove spin_unlock_wait() arch-specific definitions
  locking: Remove spin_unlock_wait() generic definitions
  drivers/ata: Replace spin_unlock_wait() with lock/unlock pair
  ipc: Replace spin_unlock_wait() with lock/unlock pair
  exit: Replace spin_unlock_wait() with lock/unlock pair
  completion: Replace spin_unlock_wait() with lock/unlock pair
  doc: Set down RCU's scheduling-clock-interrupt needs
  doc: No longer allowed to use rcu_dereference on non-pointers
  doc: Add RCU files to docbook-generation files
  doc: Update memory-barriers.txt for read-to-write dependencies
  doc: Update RCU documentation
  membarrier: Provide expedited private command
  rcu: Remove exports from rcu_idle_exit() and rcu_idle_enter()
  rcu: Add warning to rcu_idle_enter() for irqs enabled
  rcu: Make rcu_idle_enter() rely on callers disabling irqs
  rcu: Add assertions verifying blocked-tasks list
  rcu/tracing: Set disable_rcu_irq_enter on rcu_eqs_exit()
  rcu: Add TPS() protection for _rcu_barrier_trace strings
  rcu: Use idle versions of swait to make idle-hack clear
  swait: Add idle variants which don't contribute to load average
  ...
2017-09-04 08:13:52 -07:00
Ingo Molnar edc2988c54 Merge branch 'linus' into locking/core, to fix up conflicts
Conflicts:
	mm/page_alloc.c

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-09-04 11:01:18 +02:00
Rafael J. Wysocki 7b01463e51 Merge branch 'pm-sleep'
* pm-sleep:
  ACPI / PM: Check low power idle constraints for debug only
  PM / s2idle: Rename platform operations structure
  PM / s2idle: Rename ->enter_freeze to ->enter_s2idle
  PM / s2idle: Rename freeze_state enum and related items
  PM / s2idle: Rename PM_SUSPEND_FREEZE to PM_SUSPEND_TO_IDLE
  ACPI / PM: Prefer suspend-to-idle over S3 on some systems
  platform/x86: intel-hid: Wake up Dell Latitude 7275 from suspend-to-idle
  PM / suspend: Define pr_fmt() in suspend.c
  PM / suspend: Use mem_sleep_labels[] strings in messages
  PM / sleep: Put pm_test under CONFIG_PM_SLEEP_DEBUG
  PM / sleep: Check pm_wakeup_pending() in __device_suspend_noirq()
  PM / core: Add error argument to dpm_show_time()
  PM / core: Split dpm_suspend_noirq() and dpm_resume_noirq()
  PM / s2idle: Rearrange the main suspend-to-idle loop
  PM / timekeeping: Print debug messages when requested
  PM / sleep: Mark suspend/hibernation start and finish
  PM / sleep: Do not print debug messages by default
  PM / suspend: Export pm_suspend_target_state
2017-09-04 00:06:02 +02:00
Rafael J. Wysocki 08a10002be Merge branch 'pm-cpufreq-sched'
* pm-cpufreq-sched:
  cpufreq: schedutil: Always process remote callback with slow switching
  cpufreq: schedutil: Don't restrict kthread to related_cpus unnecessarily
  cpufreq: Return 0 from ->fast_switch() on errors
  cpufreq: Simplify cpufreq_can_do_remote_dvfs()
  cpufreq: Process remote callbacks from any CPU if the platform permits
  sched: cpufreq: Allow remote cpufreq callbacks
  cpufreq: schedutil: Use unsigned int for iowait boost
  cpufreq: schedutil: Make iowait boost more energy efficient
2017-09-04 00:05:22 +02:00
Rafael J. Wysocki bd87c8fb9d Merge branch 'pm-cpufreq'
* pm-cpufreq: (33 commits)
  cpufreq: imx6q: Fix imx6sx low frequency support
  cpufreq: speedstep-lib: make several arrays static, makes code smaller
  cpufreq: ti: Fix 'of_node_put' being called twice in error handling path
  cpufreq: dt-platdev: Drop few entries from whitelist
  cpufreq: dt-platdev: Automatically create cpufreq device with OPP v2
  ARM: ux500: don't select CPUFREQ_DT
  cpufreq: Convert to using %pOF instead of full_name
  cpufreq: Cap the default transition delay value to 10 ms
  cpufreq: dbx500: Delete obsolete driver
  mfd: db8500-prcmu: Get rid of cpufreq dependency
  cpufreq: enable the DT cpufreq driver on the Ux500
  cpufreq: Loongson2: constify platform_device_id
  cpufreq: dt: Add r8a7796 support to to use generic cpufreq driver
  cpufreq: remove setting of policy->cpu in policy->cpus during init
  cpufreq: mediatek: add support of cpufreq to MT7622 SoC
  cpufreq: mediatek: add cleanups with the more generic naming
  cpufreq: rcar: Add support for R8A7795 SoC
  cpufreq: dt: Add rk3328 compatible to use generic cpufreq driver
  cpufreq: s5pv210: add missing of_node_put()
  cpufreq: Allow dynamic switching with CPUFREQ_ETERNAL latency
  ...
2017-09-04 00:05:13 +02:00
Ying Huang 966a967116 smp: Avoid using two cache lines for struct call_single_data
struct call_single_data is used in IPIs to transfer information between
CPUs.  Its size is bigger than sizeof(unsigned long) and less than
cache line size.  Currently it is not allocated with any explicit alignment
requirements.  This makes it possible for allocated call_single_data to
cross two cache lines, which results in double the number of the cache lines
that need to be transferred among CPUs.

This can be fixed by requiring call_single_data to be aligned with the
size of call_single_data. Currently the size of call_single_data is the
power of 2.  If we add new fields to call_single_data, we may need to
add padding to make sure the size of new definition is the power of 2
as well.

Fortunately, this is enforced by GCC, which will report bad sizes.

To set alignment requirements of call_single_data to the size of
call_single_data, a struct definition and a typedef is used.

To test the effect of the patch, I used the vm-scalability multiple
thread swap test case (swap-w-seq-mt).  The test will create multiple
threads and each thread will eat memory until all RAM and part of swap
is used, so that huge number of IPIs are triggered when unmapping
memory.  In the test, the throughput of memory writing improves ~5%
compared with misaligned call_single_data, because of faster IPIs.

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Huang, Ying <ying.huang@intel.com>
[ Add call_single_data_t and align with size of call_single_data. ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Aaron Lu <aaron.lu@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/87bmnqd6lz.fsf@yhuang-mobile.sh.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-29 15:14:38 +02:00
Linus Torvalds 3510ca20ec Minor page waitqueue cleanups
Tim Chen and Kan Liang have been battling a customer load that shows
extremely long page wakeup lists.  The cause seems to be constant NUMA
migration of a hot page that is shared across a lot of threads, but the
actual root cause for the exact behavior has not been found.

Tim has a patch that batches the wait list traversal at wakeup time, so
that we at least don't get long uninterruptible cases where we traverse
and wake up thousands of processes and get nasty latency spikes.  That
is likely 4.14 material, but we're still discussing the page waitqueue
specific parts of it.

In the meantime, I've tried to look at making the page wait queues less
expensive, and failing miserably.  If you have thousands of threads
waiting for the same page, it will be painful.  We'll need to try to
figure out the NUMA balancing issue some day, in addition to avoiding
the excessive spinlock hold times.

That said, having tried to rewrite the page wait queues, I can at least
fix up some of the braindamage in the current situation. In particular:

 (a) we don't want to continue walking the page wait list if the bit
     we're waiting for already got set again (which seems to be one of
     the patterns of the bad load).  That makes no progress and just
     causes pointless cache pollution chasing the pointers.

 (b) we don't want to put the non-locking waiters always on the front of
     the queue, and the locking waiters always on the back.  Not only is
     that unfair, it means that we wake up thousands of reading threads
     that will just end up being blocked by the writer later anyway.

Also add a comment about the layout of 'struct wait_page_key' - there is
an external user of it in the cachefiles code that means that it has to
match the layout of 'struct wait_bit_key' in the two first members.  It
so happens to match, because 'struct page *' and 'unsigned long *' end
up having the same values simply because the page flags are the first
member in struct page.

Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Christopher Lameter <cl@linux.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-08-27 13:55:12 -07:00
Peter Zijlstra bbdacdfed2 sched/debug: Optimize sched_domain sysctl generation
Currently we unconditionally destroy all sysctl bits and regenerate
them after we've rebuild the domains (even if that rebuild is a
no-op).

And since we unconditionally (re)build the sysctl for all possible
CPUs, onlining all CPUs gets us O(n^2) time. Instead change this to
only rebuild the bits for CPUs we've actually installed new domains
on.

Reported-by: Ofer Levi(SW) <oferle@mellanox.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-25 11:12:20 +02:00
Peter Zijlstra 09e0dd8e0f sched/topology: Avoid pointless rebuild
Fix partition_sched_domains() to try and preserve the existing machine
wide domain instead of unconditionally destroying it. We do this by
attempting to allocate the new single domain, only when that fails to
we reuse the fallback_doms.

When using fallback_doms we need to first destroy and then recreate
because both the old and new could be backed by it.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ofer Levi(SW) <oferle@mellanox.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vineet.Gupta1@synopsys.com <Vineet.Gupta1@synopsys.com>
Cc: rusty@rustcorp.com.au <rusty@rustcorp.com.au>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-25 11:12:20 +02:00
Peter Zijlstra a090c4f2cd sched/topology: Improve comments
Mike provided a better comment for destroy_sched_domain() ...

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-25 11:12:19 +02:00
Shu Wang 213c5a459a sched/topology: Fix memory leak in __sdt_alloc()
Found this issue by kmemleak: the 'sg' and 'sgc' pointers from
__sdt_alloc() might be leaked as each domain holds many groups' ref,
but in destroy_sched_domain(), it only declined the first group ref.

Onlining and offlining a CPU can trigger this leak, and cause OOM.

Reproducer for my 6 CPUs machine:

  while true
  do
      echo 0 > /sys/devices/system/cpu/cpu5/online;
      echo 1 > /sys/devices/system/cpu/cpu5/online;
  done

  unreferenced object 0xffff88007d772a80 (size 64):
    comm "cpuhp/5", pid 39, jiffies 4294719962 (age 35.251s)
    hex dump (first 32 bytes):
      c0 22 77 7d 00 88 ff ff 02 00 00 00 01 00 00 00  ."w}............
      40 2a 77 7d 00 88 ff ff 00 00 00 00 00 00 00 00  @*w}............
    backtrace:
      [<ffffffff8176525a>] kmemleak_alloc+0x4a/0xa0
      [<ffffffff8121efe1>] __kmalloc_node+0xf1/0x280
      [<ffffffff810d94a8>] build_sched_domains+0x1e8/0xf20
      [<ffffffff810da674>] partition_sched_domains+0x304/0x360
      [<ffffffff81139557>] cpuset_update_active_cpus+0x17/0x40
      [<ffffffff810bdb2e>] sched_cpu_activate+0xae/0xc0
      [<ffffffff810900e0>] cpuhp_invoke_callback+0x90/0x400
      [<ffffffff81090597>] cpuhp_up_callbacks+0x37/0xb0
      [<ffffffff81090887>] cpuhp_thread_fun+0xd7/0xf0
      [<ffffffff810b37e0>] smpboot_thread_fn+0x110/0x160
      [<ffffffff810af5d9>] kthread+0x109/0x140
      [<ffffffff81770e45>] ret_from_fork+0x25/0x30
      [<ffffffffffffffff>] 0xffffffffffffffff

  unreferenced object 0xffff88007d772a40 (size 64):
    comm "cpuhp/5", pid 39, jiffies 4294719962 (age 35.251s)
    hex dump (first 32 bytes):
      03 00 00 00 00 00 00 00 00 04 00 00 00 00 00 00  ................
      00 04 00 00 00 00 00 00 4f 3c fc ff 00 00 00 00  ........O<......
    backtrace:
      [<ffffffff8176525a>] kmemleak_alloc+0x4a/0xa0
      [<ffffffff8121efe1>] __kmalloc_node+0xf1/0x280
      [<ffffffff810da16d>] build_sched_domains+0xead/0xf20
      [<ffffffff810da674>] partition_sched_domains+0x304/0x360
      [<ffffffff81139557>] cpuset_update_active_cpus+0x17/0x40
      [<ffffffff810bdb2e>] sched_cpu_activate+0xae/0xc0
      [<ffffffff810900e0>] cpuhp_invoke_callback+0x90/0x400
      [<ffffffff81090597>] cpuhp_up_callbacks+0x37/0xb0
      [<ffffffff81090887>] cpuhp_thread_fun+0xd7/0xf0
      [<ffffffff810b37e0>] smpboot_thread_fn+0x110/0x160
      [<ffffffff810af5d9>] kthread+0x109/0x140
      [<ffffffff81770e45>] ret_from_fork+0x25/0x30
      [<ffffffffffffffff>] 0xffffffffffffffff

Reported-by: Chunyu Hu <chuhu@redhat.com>
Signed-off-by: Shu Wang <shuwang@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Chunyu Hu <chuhu@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: liwang@redhat.com
Link: http://lkml.kernel.org/r/1502351536-9108-1-git-send-email-shuwang@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-25 11:12:19 +02:00
Ingo Molnar 94edf6f3c2 Merge branch 'for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu
Pull RCU updates from Paul E. McKenney:

 - Removal of spin_unlock_wait()
 - SRCU updates
 - Torture-test updates
 - Documentation updates
 - Miscellaneous fixes
 - CPU-hotplug fixes
 - Miscellaneous non-RCU fixes

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-21 09:45:19 +02:00
Viresh Kumar c49cbc19b3 cpufreq: schedutil: Always process remote callback with slow switching
The frequency update from the utilization update handlers can be divided
into two parts:

(A) Finding the next frequency
(B) Updating the frequency

While any CPU can do (A), (B) can be restricted to a group of CPUs only,
depending on the current platform.

For platforms where fast cpufreq switching is possible, both (A) and (B)
are always done from the same CPU and that CPU should be capable of
changing the frequency of the target CPU.

But for platforms where fast cpufreq switching isn't possible, after
doing (A) we wake up a kthread which will eventually do (B). This
kthread is already bound to the right set of CPUs, i.e. only those which
can change the frequency of CPUs of a cpufreq policy. And so any CPU
can actually do (A) in this case, as the frequency is updated from the
right set of CPUs only.

Check cpufreq_can_do_remote_dvfs() only for the fast switching case.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-08-18 01:35:19 +02:00
Viresh Kumar e2cabe48c2 cpufreq: schedutil: Don't restrict kthread to related_cpus unnecessarily
Utilization update callbacks are now processed remotely, even on the
CPUs that don't share cpufreq policy with the target CPU (if
dvfs_possible_from_any_cpu flag is set).

But in non-fast switch paths, the frequency is changed only from one of
policy->related_cpus. This happens because the kthread which does the
actual update is bound to a subset of CPUs (i.e. related_cpus).

Allow frequency to be remotely updated as well (i.e. call
__cpufreq_driver_target()) if dvfs_possible_from_any_cpu flag is set.

Reported-by: Pavan Kondeti <pkondeti@codeaurora.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-08-18 01:35:18 +02:00
Paul E. McKenney 656e7c0c0a Merge branches 'doc.2017.08.17a', 'fixes.2017.08.17a', 'hotplug.2017.07.25b', 'misc.2017.08.17a', 'spin_unlock_wait_no.2017.08.17a', 'srcu.2017.07.27c' and 'torture.2017.07.24c' into HEAD
doc.2017.08.17a: Documentation updates.
fixes.2017.08.17a: RCU fixes.
hotplug.2017.07.25b: CPU-hotplug updates.
misc.2017.08.17a: Miscellaneous fixes outside of RCU (give or take conflicts).
spin_unlock_wait_no.2017.08.17a: Remove spin_unlock_wait().
srcu.2017.07.27c: SRCU updates.
torture.2017.07.24c: Torture-test updates.
2017-08-17 08:10:04 -07:00
Paul E. McKenney dec13c42d2 completion: Replace spin_unlock_wait() with lock/unlock pair
There is no agreed-upon definition of spin_unlock_wait()'s semantics,
and it appears that all callers could do just as well with a lock/unlock
pair.  This commit therefore replaces the spin_unlock_wait() call in
completion_done() with spin_lock() followed immediately by spin_unlock().
This should be safe from a performance perspective because the lock
will be held only the wakeup happens really quickly.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Andrea Parri <parri.andrea@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2017-08-17 08:06:44 -07:00
Mathieu Desnoyers 22e4ebb975 membarrier: Provide expedited private command
Implement MEMBARRIER_CMD_PRIVATE_EXPEDITED with IPIs using cpumask built
from all runqueues for which current thread's mm is the same as the
thread calling sys_membarrier. It executes faster than the non-expedited
variant (no blocking). It also works on NOHZ_FULL configurations.

Scheduler-wise, it requires a memory barrier before and after context
switching between processes (which have different mm). The memory
barrier before context switch is already present. For the barrier after
context switch:

* Our TSO archs can do RELEASE without being a full barrier. Look at
  x86 spin_unlock() being a regular STORE for example.  But for those
  archs, all atomics imply smp_mb and all of them have atomic ops in
  switch_mm() for mm_cpumask(), and on x86 the CR3 load acts as a full
  barrier.

* From all weakly ordered machines, only ARM64 and PPC can do RELEASE,
  the rest does indeed do smp_mb(), so there the spin_unlock() is a full
  barrier and we're good.

* ARM64 has a very heavy barrier in switch_to(), which suffices.

* PPC just removed its barrier from switch_to(), but appears to be
  talking about adding something to switch_mm(). So add a
  smp_mb__after_unlock_lock() for now, until this is settled on the PPC
  side.

Changes since v3:
- Properly document the memory barriers provided by each architecture.

Changes since v2:
- Address comments from Peter Zijlstra,
- Add smp_mb__after_unlock_lock() after finish_lock_switch() in
  finish_task_switch() to add the memory barrier we need after storing
  to rq->curr. This is much simpler than the previous approach relying
  on atomic_dec_and_test() in mmdrop(), which actually added a memory
  barrier in the common case of switching between userspace processes.
- Return -EINVAL when MEMBARRIER_CMD_SHARED is used on a nohz_full
  kernel, rather than having the whole membarrier system call returning
  -ENOSYS. Indeed, CMD_PRIVATE_EXPEDITED is compatible with nohz_full.
  Adapt the CMD_QUERY mask accordingly.

Changes since v1:
- move membarrier code under kernel/sched/ because it uses the
  scheduler runqueue,
- only add the barrier when we switch from a kernel thread. The case
  where we switch from a user-space thread is already handled by
  the atomic_dec_and_test() in mmdrop().
- add a comment to mmdrop() documenting the requirement on the implicit
  memory barrier.

CC: Peter Zijlstra <peterz@infradead.org>
CC: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
CC: Boqun Feng <boqun.feng@gmail.com>
CC: Andrew Hunter <ahh@google.com>
CC: Maged Michael <maged.michael@gmail.com>
CC: gromer@google.com
CC: Avi Kivity <avi@scylladb.com>
CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
CC: Paul Mackerras <paulus@samba.org>
CC: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Dave Watson <davejwatson@fb.com>
2017-08-17 07:28:05 -07:00
Steven Rostedt 9c8783201c sched/completion: Document that reinit_completion() must be called after complete_all()
The complete_all() function modifies the completion's "done" variable to
UINT_MAX, and no other caller (wait_for_completion(), etc) will modify
it back to zero. That means that any call to complete_all() must have a
reinit_completion() before that completion can be used again.

Document this fact by the complete_all() function.

Also document that completion_done() will always return true if
complete_all() is called.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170816131202.195c2f4b@gandalf.local.home
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-16 20:08:10 +02:00
Paul E. McKenney 23a9b748a3 sched: Replace spin_unlock_wait() with lock/unlock pair
There is no agreed-upon definition of spin_unlock_wait()'s semantics,
and it appears that all callers could do just as well with a lock/unlock
pair.  This commit therefore replaces the spin_unlock_wait() call in
do_task_dead() with spin_lock() followed immediately by spin_unlock().
This should be safe from a performance perspective because the lock is
this tasks ->pi_lock, and this is called only after the task exits.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Andrea Parri <parri.andrea@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
[ paulmck: Drop smp_mb() based on Peter Zijlstra's analysis:
  http://lkml.kernel.org/r/20170811144150.26gowhxte7ri5fpk@hirez.programming.kicks-ass.net ]
2017-08-11 13:09:14 -07:00
Rafael J. Wysocki 28ba086ed3 PM / s2idle: Rename ->enter_freeze to ->enter_s2idle
Rename the ->enter_freeze cpuidle driver callback to ->enter_s2idle
to make it clear that it is used for entering suspend-to-idle and
rename the related functions, variables and so on accordingly.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-08-11 01:29:56 +02:00
Rafael J. Wysocki f02f4f9d82 PM / s2idle: Rename freeze_state enum and related items
Rename the freeze_state enum representing the suspend-to-idle state
machine states to s2idle_states and rename the related variables and
functions accordingly.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-08-11 01:29:55 +02:00