the 'p' (task_struct) parameter in the sched_class :: yield_task() is
redundant as the caller is always the 'current'. Get rid of it.

   text    data     bss     dec     hex filename
  24341    2734      20   27095    69d7 sched.o.before
  24330    2734      20   27084    69cc sched.o.after
Signed-off-by: NDmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>

due to the fact that we no longer keep the 'current' within the tree, 
dequeue/enqueue_entity() is useless for the 'current' in 
task_new_fair(). We are about to reschedule and 
sched_class->put_prev_task() will put the 'current' back into the tree, 
based on its new key.

   text    data     bss     dec     hex filename
  24388    2734      20   27142    6a06 sched.o.before
  24341    2734      20   27095    69d7 sched.o.after
Signed-off-by: NDmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>

fix delay accounting performance regression - those sched_clock()
calls are not needed.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>

Get rid of 'sched_entity::fair_key'.

As a side effect, 'current' is not kept withing the tree for 
SCHED_NORMAL/BATCH tasks anymore. This simplifies some parts of code 
(e.g. entity_tick() and yield_task_fair()) and also somewhat optimizes 
them (e.g. a single update_curr() now vs. dequeue/enqueue() before in 
entity_tick()).
Signed-off-by: NDmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>

p->sched_class->set_curr_task() has to be called before 
activate_task()/enqueue_task() in rt_mutex_setprio(), 
sched_setschedule() and sched_move_task() in order to set up 
'cfs_rq->curr'. The logic of enqueueing depends on whether a task to be 
inserted is 'current' or not.
Signed-off-by: NDmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>

Fix a problem in the 'sched-group' patch for !CONFIG_FAIR_GROUP_SCHED.

description:

sched_setscheduler()
{
...
if (task_running()) p->sched_class->put_prev_entity();

[ this one sets up cfs_rq->curr to NULL ]

...

if (task_running) p->sched_class->set_curr_task();

[ and this one is a _NOP_ (empty) for !CONFIG_FAIR_GROUP_SCHED ]

As a result, the task continues to run with cfs_rq->curr == NULL... no 
crashes (due to checks for !NULL in place) but e.g. update_curr() 
effectively becomes a NOP... i.e. runtime statistics for this task is 
not accounted untill it's rescheduled anew.
Signed-off-by: NDmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>

Add interface to control cpu bandwidth allocation to task-groups.

(not yet configurable, due to missing CONFIG_CONTAINERS)
Signed-off-by: NSrivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: NDhaval Giani <dhaval@linux.vnet.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>

fix SMP migration latencies: the vruntimes of different CPUs are
at incompatible offsets so they have to be fixed up when migrating
a task across CPUs.
Signed-off-by: NMike Galbraith <efault@gmx.de>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>

Better min_vruntime tracking: update it every time 'curr' is
updated - not just when a task is enqueued into the tree.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NMike Galbraith <efault@gmx.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>

sched.o gets smaller and faster if we compile it with -fomit-frame-pointers,
so make this a config option. The cost is the loss of multi-depth wchan
lookups - but SysRq-T is a sufficient replacement for them anyway, so their
utility is much lower these days.

the size difference is significant:

   text    data     bss     dec     hex filename
  34005    3462      24   37491    9273 sched.o.before
  33470    3462      24   36956    905c sched.o.after
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NMike Galbraith <efault@gmx.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>

Better placement of #ifdef CONFIG_SCHEDSTAT block in dequeue_entity().
Signed-off-by: NDmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NMike Galbraith <efault@gmx.de>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>

remove wait_runtime based fields and features, now that the CFS
math has been changed over to the vruntime metric.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NMike Galbraith <efault@gmx.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>

remove the wait_runtime-limit fields and the code depending on it, now
that the math has been changed over to rely on the vruntime metric.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NMike Galbraith <efault@gmx.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>

'struct load_stat' is redundant now so let's get rid of it.
Signed-off-by: NDmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NMike Galbraith <efault@gmx.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>

micro-optimization: update cfs_rq->exec_clock only if
CONFIG_SCHED_DEBUG=y.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NMike Galbraith <efault@gmx.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>

add more vruntime statistics.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NMike Galbraith <efault@gmx.de>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>

Handle vruntime overflow by centering the key space around min_vruntime.

( otherwise we could overflow 64-bit vruntime in a few days with SCHED_IDLE
 tasks - or in a few years with nice +19. )
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NMike Galbraith <efault@gmx.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>

add support for tree based vruntime averages.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NMike Galbraith <efault@gmx.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>

remove SCHED_FEAT_SKIP_INITIAL - it was off by default and even
when enabled it never made any real difference.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>

debug se->vruntime fields.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NMike Galbraith <efault@gmx.de>

clean up new task placement.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NMike Galbraith <efault@gmx.de>

increase wakeup granularity - we were overscheduling a bit.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NMike Galbraith <efault@gmx.de>

simplify the check_preempt() methods.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NMike Galbraith <efault@gmx.de>

simplify adaptive latency.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NMike Galbraith <efault@gmx.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>

add proper new task placement for the vruntime based math too.

( note: introduces a swap() macro, but the swap token is too
  widely used in the kernel namespace for a generic version
  to be added without changing non-scheduler code - so this
  cleanup will be done separately. )
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NMike Galbraith <efault@gmx.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>

optimize vruntime based scheduling.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NMike Galbraith <efault@gmx.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>

move sched_feat() definitions so that it can be used sooner by generic
code too.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NMike Galbraith <efault@gmx.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>

introduce se->vruntime as a sum of weighted delta-exec's, and use that
as the key into the tree.

the idea to use absolute virtual time as the basic metric of scheduling
has been first raised by William Lee Irwin, advanced by Tong Li and first
prototyped by Roman Zippel in the "Really Fair Scheduler" (RFS) patchset.

also see:

   http://lkml.org/lkml/2007/9/2/76

for a simpler variant of this patch.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NMike Galbraith <efault@gmx.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>

clean up calc_weighted() - we always use the normalized shift so
it's not needed to pass that in. Also, push the non-nice0 branch
into the function.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NMike Galbraith <efault@gmx.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>

speed up update_load_add/_sub() by not delaying the division - this
reduces CPU pipeline dependencies.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NMike Galbraith <efault@gmx.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>

suggested by Roman Zippel: uninline __enqueue_entity() and
__dequeue_entity().

this reduces code size:

      text    data     bss     dec     hex filename
     25385    2386      16   27787    6c8b sched.o.before
     25257    2386      16   27659    6c0b sched.o.after
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NMike Galbraith <efault@gmx.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>

Peter Zijlstra suggested to simplify SCHED_FEAT_* checks via the
sched_feat(x) macro.

No code changed:

   text    data     bss     dec     hex filename
   38895    3550      24   42469    a5e5 sched.o.before
   38895    3550      24   42469    a5e5 sched.o.after
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NMike Galbraith <efault@gmx.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>

cleanup: simplify cfs_rq_curr() methods - now that the cfs_rq->curr
pointer is unconditionally present, remove the wrappers.

  kernel/sched.o:
      text    data     bss     dec     hex filename
     11784     224    2012   14020    36c4 sched.o.before
     11784     224    2012   14020    36c4 sched.o.after
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NMike Galbraith <efault@gmx.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>

Noticed by Roman Zippel: use cfs_rq->curr in the !group-scheduling
case too. Small micro-optimization and cleanup effect:

   text    data     bss     dec     hex filename
   36269    3482      24   39775    9b5f sched.o.before
   36177    3486      24   39687    9b07 sched.o.after
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NMike Galbraith <efault@gmx.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>

continued removal of precise CPU load calculations.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NMike Galbraith <efault@gmx.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>

CPU load calculations are statistical anyway, and there's little benefit
from having it calculated on every scheduling event. So remove this code,
it gets rid of a divide from the scheduler wakeup and context-switch
fastpath.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NMike Galbraith <efault@gmx.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>

remove the stat_gran code - it was disabled by default and it causes
unnecessary overhead.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NMike Galbraith <efault@gmx.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>

use constants if !CONFIG_SCHED_DEBUG.

this speeds up the code and reduces code-size:

    text    data     bss     dec     hex filename
   27464    3014      16   30494    771e sched.o.before
   26929    3010      20   29959    7507 sched.o.after
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NMike Galbraith <efault@gmx.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>

use the same defaults on both UP and SMP.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NMike Galbraith <efault@gmx.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>

track the maximum amount of time a task has executed while
the CPU load was at least 2x. (i.e. at least two nice-0
tasks were runnable)
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NMike Galbraith <efault@gmx.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>