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  1. 07 2月, 2017 4 次提交
  3. 01 2月, 2017 1 次提交
  5. 30 1月, 2017 5 次提交
  7. 14 1月, 2017 9 次提交
    • T
      sched/core: Separate out io_schedule_prepare() and io_schedule_finish() · 10ab5643
      由 Tejun Heo 提交于 
      Now that IO schedule accounting is done inside __schedule(),
io_schedule() can be split into three steps - prep, schedule, and
finish - where the schedule part doesn't need any special annotation.
This allows marking a sleep as iowait by simply wrapping an existing
blocking function with io_schedule_prepare() and io_schedule_finish().

Because task_struct->in_iowait is single bit, the caller of
io_schedule_prepare() needs to record and the pass its state to
io_schedule_finish() to be safe regarding nesting.  While this isn't
the prettiest, these functions are mostly gonna be used by core
functions and we don't want to use more space for ->in_iowait.

While at it, as it's simple to do now, reimplement io_schedule()
without unnecessarily going through io_schedule_timeout().
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jens Axboe <axboe@kernel.dk>
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: adilger.kernel@dilger.ca
Cc: jack@suse.com
Cc: kernel-team@fb.com
Cc: mingbo@fb.com
Cc: tytso@mit.edu
Link: http://lkml.kernel.org/r/1477673892-28940-3-git-send-email-tj@kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
      10ab5643
    • T
      sched/core: move IO scheduling accounting from io_schedule_timeout() into scheduler · e33a9bba
      由 Tejun Heo 提交于 
      For an interface to support blocking for IOs, it must call
io_schedule() instead of schedule().  This makes it tedious to add IO
blocking to existing interfaces as the switching between schedule()
and io_schedule() is often buried deep.

As we already have a way to mark the task as IO scheduling, this can
be made easier by separating out io_schedule() into multiple steps so
that IO schedule preparation can be performed before invoking a
blocking interface and the actual accounting happens inside the
scheduler.

io_schedule_timeout() does the following three things prior to calling
schedule_timeout().

 1. Mark the task as scheduling for IO.
 2. Flush out plugged IOs.
 3. Account the IO scheduling.

done close to the actual scheduling.  This patch moves #3 into the
scheduler so that later patches can separate out preparation and
finish steps from io_schedule().
Patch-originally-by: NPeter Zijlstra <peterz@infradead.org>
Signed-off-by: NTejun Heo <tj@kernel.org>
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>
Cc: adilger.kernel@dilger.ca
Cc: akpm@linux-foundation.org
Cc: axboe@kernel.dk
Cc: jack@suse.com
Cc: kernel-team@fb.com
Cc: mingbo@fb.com
Cc: tytso@mit.edu
Link: http://lkml.kernel.org/r/20161207204841.GA22296@htj.duckdns.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
      e33a9bba
    • P
      sched/clock: Delay switching sched_clock to stable · 9881b024
      由 Peter Zijlstra 提交于 
      Currently we switch to the stable sched_clock if we guess the TSC is
usable, and then switch back to the unstable path if it turns out TSC
isn't stable during SMP bringup after all.

Delay switching to the stable path until after SMP bringup is
complete. This way we'll avoid switching during the time we detect the
worst of the TSC offences.
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>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      9881b024
    • M
      sched/core: Add debugging code to catch missing update_rq_clock() calls · cb42c9a3
      由 Matt Fleming 提交于 
      There's no diagnostic checks for figuring out when we've accidentally
missed update_rq_clock() calls. Let's add some by piggybacking on the
rq_*pin_lock() wrappers.

The idea behind the diagnostic checks is that upon pining rq lock the
rq clock should be updated, via update_rq_clock(), before anybody
reads the clock with rq_clock() or rq_clock_task().

The exception to this rule is when updates have explicitly been
disabled with the rq_clock_skip_update() optimisation.

There are some functions that only unpin the rq lock in order to grab
some other lock and avoid deadlock. In that case we don't need to
update the clock again and the previous diagnostic state can be
carried over in rq_repin_lock() by saving the state in the rq_flags
context.

Since this patch adds a new clock update flag and some already exist
in rq::clock_skip_update, that field has now been renamed. An attempt
has been made to keep the flag manipulation code small and fast since
it's used in the heart of the __schedule() fast path.

For the !CONFIG_SCHED_DEBUG case the only object code change (other
than addresses) is the following change to reset RQCF_ACT_SKIP inside
of __schedule(),

  -       c7 83 38 09 00 00 00    movl   $0x0,0x938(%rbx)
  -       00 00 00
  +       83 a3 38 09 00 00 fc    andl   $0xfffffffc,0x938(%rbx)
Suggested-by: NPeter Zijlstra <peterz@infradead.org>
Signed-off-by: NMatt Fleming <matt@codeblueprint.co.uk>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Byungchul Park <byungchul.park@lge.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luca Abeni <luca.abeni@unitn.it>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Cc: Yuyang Du <yuyang.du@intel.com>
Link: http://lkml.kernel.org/r/20160921133813.31976-8-matt@codeblueprint.co.ukSigned-off-by: NIngo Molnar <mingo@kernel.org>
      cb42c9a3
    • P
      sched/core: Add missing update_rq_clock() call in set_user_nice() · 2fb8d367
      由 Peter Zijlstra 提交于 
      Address this rq-clock update bug:

  WARNING: CPU: 30 PID: 195 at ../kernel/sched/sched.h:797 set_next_entity()
  rq->clock_update_flags < RQCF_ACT_SKIP

  Call Trace:
    dump_stack()
    __warn()
    warn_slowpath_fmt()
    set_next_entity()
    ? _raw_spin_lock()
    set_curr_task_fair()
    set_user_nice.part.85()
    set_user_nice()
    create_worker()
    worker_thread()
    kthread()
    ret_from_fork()
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>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      2fb8d367
    • P
      sched/core: Add missing update_rq_clock() in detach_task_cfs_rq() · 80f5c1b8
      由 Peter Zijlstra 提交于 
      Instead of adding the update_rq_clock() all the way at the bottom of
the callstack, add one at the top, this to aid later effort to
minimize update_rq_lock() calls.

  WARNING: CPU: 0 PID: 1 at ../kernel/sched/sched.h:797 detach_task_cfs_rq()
  rq->clock_update_flags < RQCF_ACT_SKIP

  Call Trace:
    dump_stack()
    __warn()
    warn_slowpath_fmt()
    detach_task_cfs_rq()
    switched_from_fair()
    __sched_setscheduler()
    _sched_setscheduler()
    sched_set_stop_task()
    cpu_stop_create()
    __smpboot_create_thread.part.2()
    smpboot_register_percpu_thread_cpumask()
    cpu_stop_init()
    do_one_initcall()
    ? print_cpu_info()
    kernel_init_freeable()
    ? rest_init()
    kernel_init()
    ret_from_fork()
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>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      80f5c1b8
    • P
      sched/core: Add missing update_rq_clock() in post_init_entity_util_avg() · 4126bad6
      由 Peter Zijlstra 提交于 
      Address this rq-clock update bug:

  WARNING: CPU: 0 PID: 0 at ../kernel/sched/sched.h:797 post_init_entity_util_avg()
  rq->clock_update_flags < RQCF_ACT_SKIP

  Call Trace:
    __warn()
    post_init_entity_util_avg()
    wake_up_new_task()
    _do_fork()
    kernel_thread()
    rest_init()
    start_kernel()
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>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      4126bad6
    • M
      sched/core: Reset RQCF_ACT_SKIP before unpinning rq->lock · 92509b73
      由 Matt Fleming 提交于 
      rq_clock() is called from sched_info_{depart,arrive}() after resetting
RQCF_ACT_SKIP but prior to a call to update_rq_clock().

In preparation for pending patches that check whether the rq clock has
been updated inside of a pin context before rq_clock() is called, move
the reset of rq->clock_skip_update immediately before unpinning the rq
lock.

This will avoid the new warnings which check if update_rq_clock() is
being actively skipped.
Signed-off-by: NMatt Fleming <matt@codeblueprint.co.uk>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Byungchul Park <byungchul.park@lge.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luca Abeni <luca.abeni@unitn.it>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Cc: Yuyang Du <yuyang.du@intel.com>
Link: http://lkml.kernel.org/r/20160921133813.31976-6-matt@codeblueprint.co.ukSigned-off-by: NIngo Molnar <mingo@kernel.org>
      92509b73
    • M
      sched/core: Add wrappers for lockdep_(un)pin_lock() · d8ac8971
      由 Matt Fleming 提交于 
      In preparation for adding diagnostic checks to catch missing calls to
update_rq_clock(), provide wrappers for (re)pinning and unpinning
rq->lock.

Because the pending diagnostic checks allow state to be maintained in
rq_flags across pin contexts, swap the 'struct pin_cookie' arguments
for 'struct rq_flags *'.
Signed-off-by: NMatt Fleming <matt@codeblueprint.co.uk>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Byungchul Park <byungchul.park@lge.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luca Abeni <luca.abeni@unitn.it>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Cc: Yuyang Du <yuyang.du@intel.com>
Link: http://lkml.kernel.org/r/20160921133813.31976-5-matt@codeblueprint.co.ukSigned-off-by: NIngo Molnar <mingo@kernel.org>
      d8ac8971
  9. 26 12月, 2016 1 次提交
    • T
      ktime: Cleanup ktime_set() usage · 8b0e1953
      由 Thomas Gleixner 提交于 
      ktime_set(S,N) was required for the timespec storage type and is still
useful for situations where a Seconds and Nanoseconds part of a time value
needs to be converted. For anything where the Seconds argument is 0, this
is pointless and can be replaced with a simple assignment.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
      8b0e1953
  11. 29 11月, 2016 1 次提交
    • P
      sched/idle: Add support for tasks that inject idle · c1de45ca
      由 Peter Zijlstra 提交于 
      Idle injection drivers such as Intel powerclamp and ACPI PAD drivers use
realtime tasks to take control of CPU then inject idle. There are two
issues with this approach:

 1. Low efficiency: injected idle task is treated as busy so sched ticks
    do not stop during injected idle period, the result of these
    unwanted wakeups can be ~20% loss in power savings.

 2. Idle accounting: injected idle time is presented to user as busy.

This patch addresses the issues by introducing a new PF_IDLE flag which
allows any given task to be treated as idle task while the flag is set.
Therefore, idle injection tasks can run through the normal flow of NOHZ
idle enter/exit to get the correct accounting as well as tick stop when
possible.

The implication is that idle task is then no longer limited to PID == 0.
Acked-by: NIngo Molnar <mingo@kernel.org>
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
Signed-off-by: NJacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      c1de45ca
  13. 24 11月, 2016 1 次提交
  15. 16 11月, 2016 2 次提交
    • V
      sched/fair: Fix hierarchical order in rq->leaf_cfs_rq_list · 9c2791f9
      由 Vincent Guittot 提交于 
      Fix the insertion of cfs_rq in rq->leaf_cfs_rq_list to ensure that a
child will always be called before its parent.

The hierarchical order in shares update list has been introduced by
commit:

  67e86250 ("sched: Introduce hierarchal order on shares update list")

With the current implementation a child can be still put after its
parent.

Lets take the example of:

       root
        \
         b
         /\
         c d*
           |
           e*

with root -> b -> c already enqueued but not d -> e so the
leaf_cfs_rq_list looks like: head -> c -> b -> root -> tail

The branch d -> e will be added the first time that they are enqueued,
starting with e then d.

When e is added, its parents is not already on the list so e is put at
the tail : head -> c -> b -> root -> e -> tail

Then, d is added at the head because its parent is already on the
list: head -> d -> c -> b -> root -> e -> tail

e is not placed at the right position and will be called the last
whereas it should be called at the beginning.

Because it follows the bottom-up enqueue sequence, we are sure that we
will finished to add either a cfs_rq without parent or a cfs_rq with a
parent that is already on the list. We can use this event to detect
when we have finished to add a new branch. For the others, whose
parents are not already added, we have to ensure that they will be
added after their children that have just been inserted the steps
before, and after any potential parents that are already in the list.
The easiest way is to put the cfs_rq just after the last inserted one
and to keep track of it untl the branch is fully added.
Signed-off-by: NVincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: NDietmar Eggemann <dietmar.eggemann@arm.com>
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: bsegall@google.com
Cc: kernellwp@gmail.com
Cc: pjt@google.com
Cc: yuyang.du@intel.com
Link: http://lkml.kernel.org/r/1478598827-32372-3-git-send-email-vincent.guittot@linaro.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
      9c2791f9
    • M
      sched/fair: Add per-CPU min capacity to sched_group_capacity · bf475ce0
      由 Morten Rasmussen 提交于 
      struct sched_group_capacity currently represents the compute capacity
sum of all CPUs in the sched_group.

Unless it is divided by the group_weight to get the average capacity
per CPU, it hides differences in CPU capacity for mixed capacity systems
(e.g. high RT/IRQ utilization or ARM big.LITTLE).

But even the average may not be sufficient if the group covers CPUs of
different capacities.

Instead, by extending struct sched_group_capacity to indicate min per-CPU
capacity in the group a suitable group for a given task utilization can
more easily be found such that CPUs with reduced capacity can be avoided
for tasks with high utilization (not implemented by this patch).
Signed-off-by: NMorten Rasmussen <morten.rasmussen@arm.com>
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: dietmar.eggemann@arm.com
Cc: freedom.tan@mediatek.com
Cc: keita.kobayashi.ym@renesas.com
Cc: mgalbraith@suse.de
Cc: sgurrappadi@nvidia.com
Cc: vincent.guittot@linaro.org
Cc: yuyang.du@intel.com
Link: http://lkml.kernel.org/r/1476452472-24740-4-git-send-email-morten.rasmussen@arm.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      bf475ce0
  17. 03 11月, 2016 2 次提交
  19. 28 10月, 2016 1 次提交
    • L
      mm: remove per-zone hashtable of bitlock waitqueues · 9dcb8b68
      由 Linus Torvalds 提交于 
      The per-zone waitqueues exist because of a scalability issue with the
page waitqueues on some NUMA machines, but it turns out that they hurt
normal loads, and now with the vmalloced stacks they also end up
breaking gfs2 that uses a bit_wait on a stack object:

     wait_on_bit(&gh->gh_iflags, HIF_WAIT, TASK_UNINTERRUPTIBLE)

where 'gh' can be a reference to the local variable 'mount_gh' on the
stack of fill_super().

The reason the per-zone hash table breaks for this case is that there is
no "zone" for virtual allocations, and trying to look up the physical
page to get at it will fail (with a BUG_ON()).

It turns out that I actually complained to the mm people about the
per-zone hash table for another reason just a month ago: the zone lookup
also hurts the regular use of "unlock_page()" a lot, because the zone
lookup ends up forcing several unnecessary cache misses and generates
horrible code.

As part of that earlier discussion, we had a much better solution for
the NUMA scalability issue - by just making the page lock have a
separate contention bit, the waitqueue doesn't even have to be looked at
for the normal case.

Peter Zijlstra already has a patch for that, but let's see if anybody
even notices.  In the meantime, let's fix the actual gfs2 breakage by
simplifying the bitlock waitqueues and removing the per-zone issue.
Reported-by: NAndreas Gruenbacher <agruenba@redhat.com>
Tested-by: NBob Peterson <rpeterso@redhat.com>
Acked-by: NMel Gorman <mgorman@techsingularity.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      9dcb8b68
  21. 25 10月, 2016 2 次提交
    • P
      locking/mutex: Rework mutex::owner · 3ca0ff57
      由 Peter Zijlstra 提交于 
      The current mutex implementation has an atomic lock word and a
non-atomic owner field.

This disparity leads to a number of issues with the current mutex code
as it means that we can have a locked mutex without an explicit owner
(because the owner field has not been set, or already cleared).

This leads to a number of weird corner cases, esp. between the
optimistic spinning and debug code. Where the optimistic spinning
code needs the owner field updated inside the lock region, the debug
code is more relaxed because the whole lock is serialized by the
wait_lock.

Also, the spinning code itself has a few corner cases where we need to
deal with a held lock without an owner field.

Furthermore, it becomes even more of a problem when trying to fix
starvation cases in the current code. We end up stacking special case
on special case.

To solve this rework the basic mutex implementation to be a single
atomic word that contains the owner and uses the low bits for extra
state.

This matches how PI futexes and rt_mutex already work. By having the
owner an integral part of the lock state a lot of the problems
dissapear and we get a better option to deal with starvation cases,
direct owner handoff.

Changing the basic mutex does however invalidate all the arch specific
mutex code; this patch leaves that unused in-place, a later patch will
remove that.
Tested-by: NJason Low <jason.low2@hpe.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: NWill Deacon <will.deacon@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      3ca0ff57
    • P
      sched/core: Explain sleep/wakeup in a better way · a2250238
      由 Peter Zijlstra 提交于 
      There were a few questions wrt. how sleep-wakeup works. Try and explain
it more.
Requested-by: NWill Deacon <will.deacon@arm.com>
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>
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      a2250238
  23. 30 9月, 2016 11 次提交
    • P
      sched/core: Fix set_user_nice() · 49bd21ef
      由 Peter Zijlstra 提交于 
      Almost all scheduler functions update state with the following
pattern:

	if (queued)
		dequeue_task(rq, p, DEQUEUE_SAVE);
	if (running)
		put_prev_task(rq, p);

	/* update state */

	if (queued)
		enqueue_task(rq, p, ENQUEUE_RESTORE);
	if (running)
		set_curr_task(rq, p);

set_user_nice() however misses the running part, cure this.

This was found by asserting we never enqueue 'current'.
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>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      49bd21ef
    • P
      sched/fair: Introduce set_curr_task() helper · b2bf6c31
      由 Peter Zijlstra 提交于 
      Now that the ia64 only set_curr_task() symbol is gone, provide a
helper just like put_prev_task().
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>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      b2bf6c31
    • P
      sched/core, ia64: Rename set_curr_task() · a458ae2e
      由 Peter Zijlstra 提交于 
      Rename the ia64 only set_curr_task() function to free up the name.
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>
Cc: Tony Luck <tony.luck@intel.com>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      a458ae2e
    • V
      sched/core: Fix incorrect utilization accounting when switching to fair class · a399d233
      由 Vincent Guittot 提交于 
      When a task switches to fair scheduling class, the period between now
and the last update of its utilization is accounted as running time
whatever happened during this period. This incorrect accounting applies
to the task and also to the task group branch.

When changing the property of a running task like its list of allowed
CPUs or its scheduling class, we follow the sequence:

 - dequeue task
 - put task
 - change the property
 - set task as current task
 - enqueue task

The end of the sequence doesn't follow the normal sequence (as per
__schedule()) which is:

 - enqueue a task
 - then set the task as current task.

This incorrectordering is the root cause of incorrect utilization accounting.
Update the sequence to follow the right one:

 - dequeue task
 - put task
 - change the property
 - enqueue task
 - set task as current task
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: Mike Galbraith <efault@gmx.de>
Cc: Morten.Rasmussen@arm.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bsegall@google.com
Cc: dietmar.eggemann@arm.com
Cc: linaro-kernel@lists.linaro.org
Cc: pjt@google.com
Cc: yuyang.du@intel.com
Link: http://lkml.kernel.org/r/1473666472-13749-8-git-send-email-vincent.guittot@linaro.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
      a399d233
    • P
      sched/core: Optimize SCHED_SMT · 1b568f0a
      由 Peter Zijlstra 提交于 
      Avoid pointless SCHED_SMT code when running on !SMT hardware.
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>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      1b568f0a
    • P
      sched/core: Rewrite and improve select_idle_siblings() · 10e2f1ac
      由 Peter Zijlstra 提交于 
      select_idle_siblings() is a known pain point for a number of
workloads; it either does too much or not enough and sometimes just
does plain wrong.

This rewrite attempts to address a number of issues (but sadly not
all).

The current code does an unconditional sched_domain iteration; with
the intent of finding an idle core (on SMT hardware). The problems
which this patch tries to address are:

 - its pointless to look for idle cores if the machine is real busy;
   at which point you're just wasting cycles.

 - it's behaviour is inconsistent between SMT and !SMT hardware in
   that !SMT hardware ends up doing a scan for any idle CPU in the LLC
   domain, while SMT hardware does a scan for idle cores and if that
   fails, falls back to a scan for idle threads on the 'target' core.

The new code replaces the sched_domain scan with 3 explicit scans:

 1) search for an idle core in the LLC
 2) search for an idle CPU in the LLC
 3) search for an idle thread in the 'target' core

where 1 and 3 are conditional on SMT support and 1 and 2 have runtime
heuristics to skip the step.

Step 1) is conditional on sd_llc_shared->has_idle_cores; when a cpu
goes idle and sd_llc_shared->has_idle_cores is false, we scan all SMT
siblings of the CPU going idle. Similarly, we clear
sd_llc_shared->has_idle_cores when we fail to find an idle core.

Step 2) tracks the average cost of the scan and compares this to the
average idle time guestimate for the CPU doing the wakeup. There is a
significant fudge factor involved to deal with the variability of the
averages. Esp. hackbench was sensitive to this.

Step 3) is unconditional; we assume (also per step 1) that scanning
all SMT siblings in a core is 'cheap'.

With this; SMT systems gain step 2, which cures a few benchmarks --
notably one from Facebook.

One 'feature' of the sched_domain iteration, which we preserve in the
new code, is that it would start scanning from the 'target' CPU,
instead of scanning the cpumask in cpu id order. This avoids multiple
CPUs in the LLC scanning for idle to gang up and find the same CPU
quite as much. The down side is that tasks can end up hopping across
the LLC for no apparent reason.
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>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      10e2f1ac
    • P
      sched/core: Replace sd_busy/nr_busy_cpus with sched_domain_shared · 0e369d75
      由 Peter Zijlstra 提交于 
      Move the nr_busy_cpus thing from its hacky sd->parent->groups->sgc
location into the much more natural sched_domain_shared location.
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>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      0e369d75
    • P
      sched/core: Introduce 'struct sched_domain_shared' · 24fc7edb
      由 Peter Zijlstra 提交于 
      Since struct sched_domain is strictly per cpu; introduce a structure
that is shared between all 'identical' sched_domains.

Limit to SD_SHARE_PKG_RESOURCES domains for now, as we'll only use it
for shared cache state; if another use comes up later we can easily
relax this.

While the sched_group's are normally shared between CPUs, these are
not natural to use when we need some shared state on a domain level --
since that would require the domain to have a parent, which is not a
given.
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>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      24fc7edb
    • P
      sched/core: Restructure destroy_sched_domain() · 16f3ef46
      由 Peter Zijlstra 提交于 
      There is no point in doing a call_rcu() for each domain, only do a
callback for the root sched domain and clean up the entire set in one
go.

Also make the entire call chain be called destroy_sched_domain*() to
remove confusion with the free_sched_domains() call, which does an
entirely different thing.

Both cpu_attach_domain() callers of destroy_sched_domain() can live
without the call_rcu() because at those points the sched_domain hasn't
been published yet.
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>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      16f3ef46
    • P
      sched/core: Remove unused @cpu argument from destroy_sched_domain*() · f39180ef
      由 Peter Zijlstra 提交于 
      Small cleanup; nothing uses the @cpu argument so make it go away.
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>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      f39180ef
    • T
      sched/core, x86/topology: Fix NUMA in package topology bug · 8f37961c
      由 Tim Chen 提交于 
      Current code can call set_cpu_sibling_map() and invoke sched_set_topology()
more than once (e.g. on CPU hot plug).  When this happens after
sched_init_smp() has been called, we lose the NUMA topology extension to
sched_domain_topology in sched_init_numa().  This results in incorrect
topology when the sched domain is rebuilt.

This patch fixes the bug and issues warning if we call sched_set_topology()
after sched_init_smp().
Signed-off-by: NTim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: NSrinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
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>
Cc: bp@suse.de
Cc: jolsa@redhat.com
Cc: rjw@rjwysocki.net
Link: http://lkml.kernel.org/r/1474485552-141429-2-git-send-email-srinivas.pandruvada@linux.intel.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      8f37961c