Mike provided a better comment for destroy_sched_domain() ...
Signed-off-by: NPeter 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: NIngo Molnar <mingo@kernel.org>

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: NChunyu Hu <chuhu@redhat.com>
Signed-off-by: NShu Wang <shuwang@redhat.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: NChunyu 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.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

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: NSteven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: NLinus 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.homeSigned-off-by: NIngo Molnar <mingo@kernel.org>

Its kzalloc() not kmalloc() which has failed earlier. While here
remove a redundant empty line.
Signed-off-by: NAnshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20170802084300.29487-1-khandual@linux.vnet.ibm.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

In commit:

  3fed382b ("sched/numa: Implement NUMA node level wake_affine()")

Rik changed wake_affine to consider NUMA information when balancing
between LLC domains.

There are a number of problems here which this patch tries to address:

 - LLC < NODE; in this case we'd use the wrong information to balance
 - !NUMA_BALANCING: in this case, the new code doesn't do any
   balancing at all
 - re-computes the NUMA data for every wakeup, this can mean iterating
   up to 64 CPUs for every wakeup.
 - default affine wakeups inside a cache

We address these by saving the load/capacity values for each
sched_domain during regular load-balance and using these values in
wake_affine_llc(). The obvious down-side to using cached values is
that they can be too old and poorly reflect reality.

But this way we can use LLC wide information and thus not rely on
assuming LLC matches NODE. We also don't rely on NUMA_BALANCING nor do
we have to aggegate two nodes (or even cache domains) worth of CPUs
for each wakeup.
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Fixes: 3fed382b ("sched/numa: Implement NUMA node level wake_affine()")
[ Minor readability improvements. ]
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Now that we have more than one place to get the task state,
intruduce the task_state_to_char() helper function to save some code.

No functionality changed.
Signed-off-by: NXie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: <cj.chengjian@huawei.com>
Cc: <huawei.libin@huawei.com>
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/1502095463-160172-3-git-send-email-xiexiuqi@huawei.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Currently we print the runnable task in /proc/sched_debug, but
there is no task state information.

We don't know which task is in the runqueue and which task is sleeping.

Add task state in the runnable task list, like this:

  runnable tasks:
   S           task   PID         tree-key  switches  prio     wait-time             sum-exec        sum-sleep
  -----------------------------------------------------------------------------------------------------------
   S   watchdog/239  1452       -11.917445      2811     0         0.000000         8.949306         0.000000 7 0 /
   S  migration/239  1453     20686.367740         8     0         0.000000     16215.720897         0.000000 7 0 /
   S  ksoftirqd/239  1454    115383.841071        12   120         0.000000         0.200683         0.000000 7 0 /
  >R           test 21287      4872.190970       407   120         0.000000      4874.911790         0.000000 7 0 /autogroup-150
   R           test 21288      4868.385454       401   120         0.000000      3672.341489         0.000000 7 0 /autogroup-150
   R           test 21289      4868.326776       384   120         0.000000      3424.934159         0.000000 7 0 /autogroup-150
Signed-off-by: NXie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: <cj.chengjian@huawei.com>
Cc: <huawei.libin@huawei.com>
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/1502095463-160172-2-git-send-email-xiexiuqi@huawei.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

It appears as though the addition of the PID namespace did not update
the output code for /proc/*/sched, which resulted in it providing PIDs
that were not self-consistent with the /proc mount. This additionally
made it trivial to detect whether a process was inside &init_pid_ns from
userspace, making container detection trivial:

   https://github.com/jessfraz/amicontained

This leads to situations such as:

  % unshare -pmf
  % mount -t proc proc /proc
  % head -n1 /proc/1/sched
  head (10047, #threads: 1)

Fix this by just using task_pid_nr_ns for the output of /proc/*/sched.
All of the other uses of task_pid_nr in kernel/sched/debug.c are from a
sysctl context and thus don't need to be namespaced.
Signed-off-by: NAleksa Sarai <asarai@suse.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: NEric W. Biederman <ebiederm@xmission.com>
Cc: Jess Frazelle <acidburn@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: cyphar@cyphar.com
Link: http://lkml.kernel.org/r/20170806044141.5093-1-asarai@suse.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

init_idle_bootup_task( ) is called in rest_init( ) to switch
the scheduling class of the boot thread to the idle class.

the function only sets:

    idle->sched_class = &idle_sched_class;

which has been set in init_idle() called by sched_init():

    /*
     * The idle tasks have their own, simple scheduling class:
     */
    idle->sched_class = &idle_sched_class;

We've already set the boot thread to idle class in
start_kernel()->sched_init()->init_idle()
so it's unnecessary to set it again in
start_kernel()->rest_init()->init_idle_bootup_task()
Signed-off-by: NCheng Jian <cj.chengjian@huawei.com>
Signed-off-by: NXie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: <akpm@linux-foundation.org>
Cc: <huawei.libin@huawei.com>
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/1501838377-109720-1-git-send-email-cj.chengjian@huawei.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

cpudl_find() users are only interested in knowing if suitable CPU(s)
were found or not (and then they look at later_mask to know which).

Change cpudl_find() return type accordingly. Aligns with rt code.
Signed-off-by: NByungchul Park <byungchul.park@lge.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: <bristot@redhat.com>
Cc: <juri.lelli@gmail.com>
Cc: <kernel-team@lge.com>
Cc: <rostedt@goodmis.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/1495504859-10960-3-git-send-email-byungchul.park@lge.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

When cpudl_find() returns any among free_cpus, the CPU might not be
closer than others, considering sched domain. For example:

   this_cpu: 15
   free_cpus: 0, 1,..., 14 (== later_mask)
   best_cpu: 0

   topology:

   0 --+
       +--+
   1 --+  |
          +-- ... --+
   2 --+  |         |
       +--+         |
   3 --+            |

   ...             ...

   12 --+           |
        +--+        |
   13 --+  |        |
           +-- ... -+
   14 --+  |
        +--+
   15 --+

In this case, it would be best to select 14 since it's a free CPU and
closest to 15 (this_cpu). However, currently the code selects 0 (best_cpu)
even though that's just any among free_cpus. Fix it.

This (re)aligns the deadline behaviour with the rt behaviour.
Signed-off-by: NByungchul Park <byungchul.park@lge.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: <bristot@redhat.com>
Cc: <juri.lelli@gmail.com>
Cc: <kernel-team@lge.com>
Cc: <rostedt@goodmis.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/1495504859-10960-2-git-send-email-byungchul.park@lge.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Running 80 tasks in the same group, or as threads of the same process,
results in the memory getting scanned 80x as fast as it would be if a
single task was using the memory.

This really hurts some workloads.

Scale the scan period by the number of tasks in the numa group, and
the shared / private ratio, so the average rate at which memory in
the group is scanned corresponds roughly to the rate at which a single
task would scan its memory.
Signed-off-by: NRik van Riel <riel@redhat.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: NMel Gorman <mgorman@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: jhladky@redhat.com
Cc: lvenanci@redhat.com
Link: http://lkml.kernel.org/r/20170731192847.23050-3-riel@redhat.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

The comment above update_task_scan_period() says the scan period should
be increased (scanning slows down) if the majority of memory accesses
are on the local node, or if the majority of the page accesses are
shared with other tasks.

However, with the current code, all a high ratio of shared accesses
does is slow down the rate at which scanning is made faster.

This patch changes things so either lots of shared accesses or
lots of local accesses will slow down scanning, and numa scanning
is sped up only when there are lots of private faults on remote
memory pages.
Signed-off-by: NRik van Riel <riel@redhat.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: NMel Gorman <mgorman@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: jhladky@redhat.com
Cc: lvenanci@redhat.com
Link: http://lkml.kernel.org/r/20170731192847.23050-2-riel@redhat.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

The running state is a subset of runnable state which means that running
can't be set if runnable (weight) is cleared. There are corner cases
where the current sched_entity has been already dequeued but cfs_rq->curr
has not been updated yet and still points to the dequeued sched_entity.
If ___update_load_avg() is called at that time, weight will be 0 and running
will be set which is not possible.

This case happens during pick_next_task_fair() when a cfs_rq becomes idles.
The current sched_entity has been dequeued so se->on_rq is cleared and
cfs_rq->weight is null. But cfs_rq->curr still points to se (it will be
cleared when picking the idle thread). Because the cfs_rq becomes idle,
idle_balance() is called and ends up to call update_blocked_averages()
with these wrong running and runnable states.

Add a test in ___update_load_avg() to correct the running state in this case.
Signed-off-by: NVincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten.Rasmussen@arm.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Link: http://lkml.kernel.org/r/1498885573-18984-1-git-send-email-vincent.guittot@linaro.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

pick_next_task_dl() and build_sched_domain() aren't used outside
deadline.c and topology.c.

Make them static.
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NPeter 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: Vincent Guittot <vincent.guittot@linaro.org>
Cc: linaro-kernel@lists.linaro.org
Link: http://lkml.kernel.org/r/36e4cbb6210002cadae89920ae97e19e7e513008.1493281605.git.viresh.kumar@linaro.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

The 'struct cpupri' passed to cpupri_init() is already initialized to
zero. Don't do that again.
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NPeter 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: Vincent Guittot <vincent.guittot@linaro.org>
Cc: linaro-kernel@lists.linaro.org
Link: http://lkml.kernel.org/r/8a71d48c5a077500b6ddc1a41484c0ac8d3aad94.1492065513.git.viresh.kumar@linaro.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

The 'struct cpudl' passed to cpudl_init() is already initialized to zero.
Don't do that again.
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NPeter 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: Vincent Guittot <vincent.guittot@linaro.org>
Cc: linaro-kernel@lists.linaro.org
Link: http://lkml.kernel.org/r/bd4c229806bc96694b15546207afcc221387d2f5.1492065513.git.viresh.kumar@linaro.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

There are only two callers of init_rootdomain(). One of them passes a
global to it and another one sends dynamically allocated root-domain.

There is no need to memset the root-domain in the first case as the
structure is already reset.

Update alloc_rootdomain() to allocate the memory with kzalloc() and
remove the memset() call from init_rootdomain().
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NPeter 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: Vincent Guittot <vincent.guittot@linaro.org>
Cc: linaro-kernel@lists.linaro.org
Link: http://lkml.kernel.org/r/fc2f6cc90b098040970c85a97046512572d765bc.1492065513.git.viresh.kumar@linaro.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

update_freq is always true and there is no need to pass it to
update_cfs_rq_load_avg(). Remove it.
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NPeter 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: Vincent Guittot <vincent.guittot@linaro.org>
Cc: linaro-kernel@lists.linaro.org
Link: http://lkml.kernel.org/r/2d28d295f3f591ede7e931462bce1bda5aaa4896.1495603536.git.viresh.kumar@linaro.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

Rearrange pick_next_task_fair() a bit to avoid checking
cfs_rq->nr_running twice for the case where FAIR_GROUP_SCHED is enabled
and the previous task doesn't belong to the fair class.
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NPeter 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: Vincent Guittot <vincent.guittot@linaro.org>
Cc: linaro-kernel@lists.linaro.org
Link: http://lkml.kernel.org/r/000903ab3df3350943d3271c53615893a230dc95.1495603536.git.viresh.kumar@linaro.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

weighted_cpuload() uses the cpu number passed to it get pointer to the
runqueue. Almost all callers of weighted_cpuload() already have the rq
pointer with them and can send that directly to weighted_cpuload(). In
some cases the callers actually get the CPU number by doing cpu_of(rq).

It would be simpler to pass rq to weighted_cpuload().
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NPeter 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: Vincent Guittot <vincent.guittot@linaro.org>
Cc: linaro-kernel@lists.linaro.org
Link: http://lkml.kernel.org/r/b7720627e0576dc29b4ba3f9b6edbc913bb4f684.1495603536.git.viresh.kumar@linaro.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

Reuse put_prev_task() instead of copying its implementation.
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NPeter 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: Vincent Guittot <vincent.guittot@linaro.org>
Cc: linaro-kernel@lists.linaro.org
Link: http://lkml.kernel.org/r/e2e50578223d05c5e90a9feb964fe1ec5d09a052.1495603536.git.viresh.kumar@linaro.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

For SMP systems, update_load_avg() calls the cpufreq update util
handlers only for the top level cfs_rq (i.e. rq->cfs).

But that is not the case for UP systems. update_load_avg() calls util
handler for any cfs_rq for which it is called. This would result in way
too many calls from the scheduler to the cpufreq governors when
CONFIG_FAIR_GROUP_SCHED is enabled.

Reduce the frequency of these calls by copying the behavior from the SMP
case, i.e. Only call util handlers for the top level cfs_rq.
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NPeter 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: Vincent Guittot <vincent.guittot@linaro.org>
Cc: linaro-kernel@lists.linaro.org
Fixes: 536bd00c ("sched/fair: Fix !CONFIG_SMP kernel cpufreq governor breakage")
Link: http://lkml.kernel.org/r/6abf69a2107525885b616a2c1ec03d9c0946171c.1495603536.git.viresh.kumar@linaro.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

The kerneldoc comments for try_to_wake_up_local() were out of date, leading
to these documentation build warnings:

  ./kernel/sched/core.c:2080: warning: No description found for parameter 'rf'
  ./kernel/sched/core.c:2080: warning: Excess function parameter 'cookie' description in 'try_to_wake_up_local'

Update the comment to reflect current reality and give us some peace and
quiet.
Signed-off-by: NJonathan Corbet <corbet@lwn.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-doc@vger.kernel.org
Link: http://lkml.kernel.org/r/20170724135628.695cecfc@lwn.netSigned-off-by: NIngo Molnar <mingo@kernel.org>

This comment in the code is incomplete, and I believe it begs a definition of
dl_boosted to make sense of the condition that follows. Rewrite the comment and
also rearrange the condition that follows to reflect the first condition "we
have a top pi-waiter which is a SCHED_DEADLINE task" in that order. Also fix a
typo that follows.
Signed-off-by: NJoel Fernandes <joelaf@google.com>
Reviewed-by: NDaniel Bristot de Oliveira <bristot@redhat.com>
Acked-by: NJuri Lelli <juri.lelli@arm.com>
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/20170713022429.10307-1-joelaf@google.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Recent kernels trigger this warning:

 BUG: using smp_processor_id() in preemptible [00000000] code: 99-trinity/181
 caller is debug_smp_processor_id+0x17/0x19
 CPU: 0 PID: 181 Comm: 99-trinity Not tainted 4.12.0-01059-g2a42eb95 #1
 Call Trace:
  dump_stack+0x82/0xb8
  check_preemption_disabled()
  debug_smp_processor_id()
  vtime_delta()
  task_cputime()
  thread_group_cputime()
  thread_group_cputime_adjusted()
  wait_consider_task()
  do_wait()
  SYSC_wait4()
  do_syscall_64()
  entry_SYSCALL64_slow_path()

As Frederic pointed out:

| Although those sched_clock_cpu() things seem to only matter when the
| sched_clock() is unstable. And that stability is a condition for nohz_full
| to work anyway. So probably sched_clock() alone would be enough.

This patch fixes it by replacing sched_clock_cpu() with sched_clock() to
avoid calling smp_processor_id() in a preemptible context.
Reported-by: NXiaolong Ye <xiaolong.ye@intel.com>
Signed-off-by: NWanpeng Li <wanpeng.li@hotmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1499586028-7402-1-git-send-email-wanpeng.li@hotmail.com
[ Prettified the changelog. ]
Signed-off-by: NIngo Molnar <mingo@kernel.org>

With a shared policy in place, when one of the CPUs in the policy is
hotplugged out and then brought back online, sugov_stop() and
sugov_start() are called in order.

sugov_stop() removes utilization hooks for each CPU in the policy and
does nothing else in the for_each_cpu() loop. sugov_start() on the
other hand iterates through the CPUs in the policy and re-initializes
the per-cpu structure _and_ adds the utilization hook.  This implies
that the scheduler is allowed to invoke a CPU's utilization update
hook when the rest of the per-cpu structures have yet to be
re-inited.

Apart from some strange values in tracepoints this doesn't cause a
problem, but if we do end up accessing a pointer from the per-cpu
sugov_cpu structure somewhere in the sugov_update_shared() path,
we will likely see crashes since the memset for another CPU in the
policy is free to race with sugov_update_shared from the CPU that is
ready to go.  So let's fix this now to first init all per-cpu
structures, and then add the per-cpu utilization update hooks all at
once.
Signed-off-by: NVikram Mulukutla <markivx@codeaurora.org>
Acked-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

If load_balance() fails to migrate any tasks because all tasks were
affined, load_balance() removes the source CPU from consideration and
attempts to redo and balance among the new subset of CPUs.

There is a bug in this code path where the algorithm considers all active
CPUs in the system (minus the source that was just masked out).  This is
not valid for two reasons: some active CPUs may not be in the current
scheduling domain and one of the active CPUs is dst_cpu. These CPUs should
not be considered, as we cannot pull load from them.

Instead of failing out of load_balance(), we may end up redoing the search
with no valid CPUs and incorrectly concluding the domain is balanced.
Additionally, if the group_imbalance flag was just set, it may also be
incorrectly unset, thus the flag will not be seen by other CPUs in future
load_balance() runs as that algorithm intends.

Fix the check by removing CPUs not in the current domain and the dst_cpu
from considertation, thus limiting the evaluation to valid remaining CPUs
from which load might be migrated.
Co-authored-by: NAustin Christ <austinwc@codeaurora.org>
Co-authored-by: NDietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: NTyler Baicar <tbaicar@codeaurora.org>
Signed-off-by: NJeffrey Hugo <jhugo@codeaurora.org>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Austin Christ <austinwc@codeaurora.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Timur Tabi <timur@codeaurora.org>
Link: http://lkml.kernel.org/r/1496863138-11322-2-git-send-email-jhugo@codeaurora.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

Currently the cputime source used by vtime is jiffies. When we cross
a context boundary and jiffies have changed since the last snapshot, the
pending cputime is accounted to the switching out context.

This system works ok if the ticks are not aligned across CPUs. If they
instead are aligned (ie: all fire at the same time) and the CPUs run in
userspace, the jiffies change is only observed on tick exit and therefore
the user cputime is accounted as system cputime. This is because the
CPU that maintains timekeeping fires its tick at the same time as the
others. It updates jiffies in the middle of the tick and the other CPUs
see that update on IRQ exit:

    CPU 0 (timekeeper)                  CPU 1
    -------------------              -------------
                      jiffies = N
    ...                              run in userspace for a jiffy
    tick entry                       tick entry (sees jiffies = N)
    set jiffies = N + 1
    tick exit                        tick exit (sees jiffies = N + 1)
                                                account 1 jiffy as stime

Fix this with using a nanosec clock source instead of jiffies. The
cputime is then accumulated and flushed everytime the pending delta
reaches a jiffy in order to mitigate the accounting overhead.

[ fweisbec: changelog, rebase on struct vtime, field renames, add delta
  on cputime readers, keep idle vtime as-is (low overhead accounting),
  harmonize clock sources. ]
Suggested-by: NThomas Gleixner <tglx@linutronix.de>
Reported-by: NLuiz Capitulino <lcapitulino@redhat.com>
Tested-by: NLuiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: NWanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NRik van Riel <riel@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wanpeng Li <kernellwp@gmail.com>
Link: http://lkml.kernel.org/r/1498756511-11714-6-git-send-email-fweisbec@gmail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

We are about to add vtime accumulation fields to the task struct. Let's
avoid more bloatification and gather vtime information to their own
struct.
Tested-by: NLuiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NRik van Riel <riel@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wanpeng Li <kernellwp@gmail.com>
Link: http://lkml.kernel.org/r/1498756511-11714-5-git-send-email-fweisbec@gmail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

The current "snapshot" based naming on vtime fields suggests we record
some past event but that's a low level picture of their actual purpose
which comes out blurry. The real point of these fields is to run a basic
state machine that tracks down cputime entry while switching between
contexts.

So lets reflect that with more meaningful names.
Tested-by: NLuiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NRik van Riel <riel@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wanpeng Li <kernellwp@gmail.com>
Link: http://lkml.kernel.org/r/1498756511-11714-4-git-send-email-fweisbec@gmail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Even though it doesn't have functional consequences, setting
the task's new context state after we actually accounted the pending
vtime from the old context state makes more sense from a review
perspective.

vtime_user_exit() is the only function that doesn't follow that rule
and that can bug the reviewer for a little while until he realizes there
is no reason for this special case.
Tested-by: NLuiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NRik van Riel <riel@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wanpeng Li <kernellwp@gmail.com>
Link: http://lkml.kernel.org/r/1498756511-11714-3-git-send-email-fweisbec@gmail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

It's an unnecessary function between vtime_user_exit() and
account_user_time().
Tested-by: NLuiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NRik van Riel <riel@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wanpeng Li <kernellwp@gmail.com>
Link: http://lkml.kernel.org/r/1498756511-11714-2-git-send-email-fweisbec@gmail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

This reverts commit 72298e5c.

As Peter explains:

> Argh, no... That code was perfectly fine. The new code otoh is
> convoluted.
>
> The old code had the following form:
>
>         if (exception1)
>           deal with exception1
>
>         if (execption2)
>           deal with exception2
>
>         do normal stuff
>
> Which is as simple and straight forward as it gets.
>
> The new code otoh reads like:
>
>         if (!exception1) {
>                 if (exception2)
>                   deal with exception 2
>                 else
>                   do normal stuff
>         }

So restore the old form.

Also fix the comment describing the logic, as it was confusing.
Requested-by: NPeter Zijlstra <peterz@infradead.org>
Cc: Gustavo A. R. Silva <garsilva@embeddedor.com>
Cc: Frans Klaver <fransklaver@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Address a Coverity false positive, which is caused by overly
convoluted code:

Value assigned to variable 'utime' at line 619:utime = rtime;
is overwritten at line 642:utime = rtime - stime; before it
can be used. This makes such variable assignment useless.

Remove this variable assignment and refactor the code related.

Addresses-Coverity-ID: 1371643
Signed-off-by: NGustavo A. R. Silva <garsilva@embeddedor.com>
Cc: Frans Klaver <fransklaver@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Link: http://lkml.kernel.org/r/20170629184128.GA5271@embeddedgusSigned-off-by: NIngo Molnar <mingo@kernel.org>

Add the value of the rt_rq.rt_nr_migratory and dl_rq.dl_nr_migratory
to the sched_debug output, for instance:

 rt_rq[0]:
   .rt_nr_running                 : 2
   .rt_nr_migratory               : 1     <--- Like this
   .rt_throttled                  : 0
   .rt_time                       : 828.645877
   .rt_runtime                    : 1000.000000

This is useful to debug problems related to the RT/DL schedulers.

This also fixes the format of some variables, that were unsigned, rather
than signed.
Signed-off-by: NDaniel Bristot de Oliveira <bristot@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luis Claudio R. Goncalves <lgoncalv@redhat.com>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-rt-users <linux-rt-users@vger.kernel.org>
Link: http://lkml.kernel.org/r/7896f71cada54ee7dd8507bb666063a2e051c3d4.1498482127.git.bristot@redhat.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Stephen reported the following build warning in UP:

kernel/sched/fair.c:2657:9: warning: 'struct sched_domain' declared inside
parameter list
         ^
/home/sfr/next/next/kernel/sched/fair.c:2657:9: warning: its scope is only this
definition or declaration, which is probably not what you want

Hide the numa_wake_affine() inline stub on UP builds to get rid of it.

Fixes: 3fed382b ("sched/numa: Implement NUMA node level wake_affine()")
Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>

The effective_load() function was only used by the NUMA balancing
code, and not by the regular load balancing code. Now that the
NUMA balancing code no longer uses it either, get rid of it.
Signed-off-by: NRik van Riel <riel@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: jhladky@redhat.com
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/20170623165530.22514-5-riel@redhat.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Since select_idle_sibling() can place a task anywhere on a socket,
comparing loads between individual CPU cores makes no real sense
for deciding whether to do an affine wakeup across sockets, either.

Instead, compare the load between the sockets in a similar way the
load balancer and the numa balancing code do.
Signed-off-by: NRik van Riel <riel@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: jhladky@redhat.com
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/20170623165530.22514-4-riel@redhat.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Then 'this_cpu' and 'prev_cpu' are in the same socket, select_idle_sibling()
will do its thing regardless of the return value of wake_affine().

Just return true and don't look at all the other things.
Signed-off-by: NRik van Riel <riel@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: jhladky@redhat.com
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/20170623165530.22514-3-riel@redhat.comSigned-off-by: NIngo Molnar <mingo@kernel.org>