Commit Graph

153 Commits

Author SHA1 Message Date
Peter Zijlstra
ddc9729750 sched debug: check spread
debug feature: check how well we schedule within a reasonable
vruntime 'spread' range. (note that CPU overload can increase
the spread, so this is not a hard condition, but normal loads
should be within the spread.)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
2007-10-15 17:00:10 +02:00
Peter Zijlstra
67e9fb2a39 sched: add vslice
add vslice: the load-dependent "virtual slice" a task should
run ideally, so that the observed latency stays within the
sched_latency window.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:10 +02:00
Ingo Molnar
c18b8a7cbc sched: remove unneeded tunables
remove unneeded tunables.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:10 +02:00
Srivatsa Vaddagiri
9b5b77512d sched: clean up code under CONFIG_FAIR_GROUP_SCHED
With the view of supporting user-id based fair scheduling (and not just
container-based fair scheduling), this patch renames several functions
and makes them independent of whether they are being used for container
or user-id based fair scheduling.

Also fix a problem reported by KAMEZAWA Hiroyuki (wrt allocating
less-sized array for tg->cfs_rq[] and tf->se[]).

Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:09 +02:00
Srivatsa Vaddagiri
75c28ace9f sched: print &rq->cfs stats
- Print &rq->cfs statistics as well (useful for group scheduling)

Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:09 +02:00
Srivatsa Vaddagiri
72ea22f8fb sched: fix minor bug in yield
- fix a minor bug in yield (seen for CONFIG_FAIR_GROUP_SCHED),
  group scheduling would skew when yield was called.

Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:08 +02:00
Srivatsa Vaddagiri
83b699ed20 sched: revert recent removal of set_curr_task()
Revert removal of set_curr_task.
Use put_prev_task/set_curr_task when changing groups/policies

Signed-off-by: Srivatsa Vaddagiri < vatsa@linux.vnet.ibm.com>
Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
2007-10-15 17:00:08 +02:00
Ingo Molnar
edcb60a309 sched: kernel/sched_fair.c whitespace cleanups
some trivial whitespace cleanups.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:08 +02:00
Dmitry Adamushko
f6b53205e1 sched: rework enqueue/dequeue_entity() to get rid of set_curr_task()
rework enqueue/dequeue_entity() to get rid of 
sched_class::set_curr_task(). This simplifies sched_setscheduler(), 
rt_mutex_setprio() and sched_move_tasks().

   text    data     bss     dec     hex filename
  24330    2734      20   27084    69cc sched.o.before
  24233    2730      20   26983    6967 sched.o.after

Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:08 +02:00
Dmitry Adamushko
4530d7ab0f sched: simplify sched_class::yield_task()
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: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:08 +02:00
Dmitry Adamushko
87fefa381e sched: optimize task_new_fair()
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: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:08 +02:00
Dmitry Adamushko
30cfdcfc5f sched: do not keep current in the tree and get rid of sched_entity::fair_key
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: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:07 +02:00
Dmitry Adamushko
d02e5ed8d5 sched: sched_setscheduler() fix
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: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:07 +02:00
Srivatsa Vaddagiri
29f59db3a7 sched: group-scheduler core
Add interface to control cpu bandwidth allocation to task-groups.

(not yet configurable, due to missing CONFIG_CONTAINERS)

Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
2007-10-15 17:00:07 +02:00
Peter Zijlstra
02e0431a3d sched: better min_vruntime tracking
Better min_vruntime tracking: update it every time 'curr' is
updated - not just when a task is enqueued into the tree.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:07 +02:00
Dmitry Adamushko
db36cc7d6d sched: clean up schedstat block in dequeue_entity()
Better placement of #ifdef CONFIG_SCHEDSTAT block in dequeue_entity().

Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:06 +02:00
Ingo Molnar
bbdba7c0e1 sched: remove wait_runtime fields and features
remove wait_runtime based fields and features, now that the CFS
math has been changed over to the vruntime metric.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:06 +02:00
Ingo Molnar
e22f5bbf86 sched: remove wait_runtime limit
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: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:06 +02:00
Dmitry Adamushko
495eca494a sched: clean up struct load_stat
'struct load_stat' is redundant now so let's get rid of it.

Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:06 +02:00
Ingo Molnar
7a62eabc4d sched: debug: update exec_clock only when SCHED_DEBUG
micro-optimization: update cfs_rq->exec_clock only if
CONFIG_SCHED_DEBUG=y.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:06 +02:00
Peter Zijlstra
9014623c0e sched: handle vruntime 64-bit overflow
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: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:05 +02:00
Peter Zijlstra
94dfb5e75e sched: add tree based averages
add support for tree based vruntime averages.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:05 +02:00
Ingo Molnar
28a1f6fa2f sched: remove SCHED_FEAT_SKIP_INITIAL
remove SCHED_FEAT_SKIP_INITIAL - it was off by default and even
when enabled it never made any real difference.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:05 +02:00
Peter Zijlstra
aeb73b0403 sched: clean up new task placement
clean up new task placement.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Mike Galbraith <efault@gmx.de>
2007-10-15 17:00:05 +02:00
Ingo Molnar
2e09bf556f sched: wakeup granularity increase
increase wakeup granularity - we were overscheduling a bit.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
2007-10-15 17:00:05 +02:00
Ingo Molnar
5c6b5964a0 sched: simplify check_preempt() methods
simplify the check_preempt() methods.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
2007-10-15 17:00:05 +02:00
Peter Zijlstra
6d0f0ebd06 sched: simplify adaptive latency
simplify adaptive latency.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:05 +02:00
Peter Zijlstra
4d78e7b656 sched: new task placement for vruntime
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: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:04 +02:00
Ingo Molnar
6cb5819514 sched: optimize vruntime based scheduling
optimize vruntime based scheduling.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:04 +02:00
Ingo Molnar
bf5c91ba8c sched: move sched_feat() definitions
move sched_feat() definitions so that it can be used sooner by generic
code too.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:04 +02:00
Ingo Molnar
e9acbff648 sched: introduce se->vruntime
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: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:04 +02:00
Ingo Molnar
08e2388aa1 sched: clean up calc_weighted()
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: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:04 +02:00
Ingo Molnar
19ccd97a03 sched: uninline __enqueue_entity()/__dequeue_entity()
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: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:04 +02:00
Peter Zijlstra
e59c80c5bb sched: simplify SCHED_FEAT_* code
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: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:03 +02:00
Ingo Molnar
429d43bcc0 sched: cleanup: simplify cfs_rq_curr() methods
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: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:03 +02:00
Ingo Molnar
62160e3f4a sched: track cfs_rq->curr on !group-scheduling too
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: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:03 +02:00
Ingo Molnar
a25707f3ae sched: remove precise CPU load
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: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:03 +02:00
Ingo Molnar
8ebc91d936 sched: remove stat_gran
remove the stat_gran code - it was disabled by default and it causes
unnecessary overhead.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:03 +02:00
Ingo Molnar
2bd8e6d422 sched: use constants if !CONFIG_SCHED_DEBUG
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: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:02 +02:00
Ingo Molnar
eba1ed4b7e sched: debug: track maximum 'slice'
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: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:02 +02:00
Ingo Molnar
bb61c21083 sched: resched task in task_new_fair()
to get full child-runs-first semantics make sure the parent is
rescheduled.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:02 +02:00
Ingo Molnar
30084fbd1c sched: fix profile=sleep
fix sleep profiling - we lost this chunk in the CFS merge.

Found-by: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-02 14:13:08 +02:00
Ingo Molnar
1799e35d5b sched: add /proc/sys/kernel/sched_compat_yield
add /proc/sys/kernel/sched_compat_yield to make sys_sched_yield()
more agressive, by moving the yielding task to the last position
in the rbtree.

with sched_compat_yield=0:

   PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
  2539 mingo     20   0  1576  252  204 R   50  0.0   0:02.03 loop_yield
  2541 mingo     20   0  1576  244  196 R   50  0.0   0:02.05 loop

with sched_compat_yield=1:

   PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
  2584 mingo     20   0  1576  248  196 R   99  0.0   0:52.45 loop
  2582 mingo     20   0  1576  256  204 R    0  0.0   0:00.00 loop_yield

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
2007-09-19 23:34:46 +02:00
Peter Zijlstra
1169783085 sched: fix ideal_runtime calculations for reniced tasks
fix ideal_runtime:

  - do not scale it using niced_granularity()
    it is against sum_exec_delta, so its wall-time, not fair-time.

  - move the whole check into __check_preempt_curr_fair()
    so that wakeup preemption can also benefit from the new logic.

this also results in code size reduction:

   text    data     bss     dec     hex filename
  13391     228    1204   14823    39e7 sched.o.before
  13369     228    1204   14801    39d1 sched.o.after

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-09-05 14:32:49 +02:00
Peter Zijlstra
4a55b45036 sched: improve prev_sum_exec_runtime setting
Second preparatory patch for fix-ideal runtime:

Mark prev_sum_exec_runtime at the beginning of our run, the same spot
that adds our wait period to wait_runtime. This seems a more natural
location to do this, and it also reduces the code a bit:

   text    data     bss     dec     hex filename
  13397     228    1204   14829    39ed sched.o.before
  13391     228    1204   14823    39e7 sched.o.after

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-09-05 14:32:49 +02:00
Peter Zijlstra
7c92e54f6f sched: simplify __check_preempt_curr_fair()
Preparatory patch for fix-ideal-runtime:

simplify __check_preempt_curr_fair(): get rid of the integer return.

   text    data     bss     dec     hex filename
  13404     228    1204   14836    39f4 sched.o.before
  13393     228    1204   14825    39e9 sched.o.after

functionality is unchanged.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-09-05 14:32:49 +02:00
Ingo Molnar
a206c07213 sched: debug: fix cfs_rq->wait_runtime accounting
the cfs_rq->wait_runtime debug/statistics counter was not maintained
properly - fix this.

this also removes some code:

   text    data     bss     dec     hex filename
  13420     228    1204   14852    3a04 sched.o.before
  13404     228    1204   14836    39f4 sched.o.after

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
2007-09-05 14:32:49 +02:00
Ingo Molnar
a0dc72601d sched: fix niced_granularity() shift
fix niced_granularity(). This resulted in under-scheduling for
CPU-bound negative nice level tasks (and this in turn caused
higher than necessary latencies in nice-0 tasks).

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-09-05 14:32:49 +02:00
Ingo Molnar
9f508f8258 sched: clean up task_new_fair()
cleanup: we have the 'se' and 'curr' entity-pointers already,
no need to use p->se and current->se.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
2007-08-28 12:53:24 +02:00
Ingo Molnar
213c8af67f sched: small schedstat fix
small schedstat fix: the cfs_rq->wait_runtime 'sum of all runtimes'
statistics counters missed newly forked tasks and thus had a constant
negative skew. Fix this.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
2007-08-28 12:53:24 +02:00
Ingo Molnar
b77d69db9f sched: fix wait_start_fair condition in update_stats_wait_end()
Peter Zijlstra noticed the following bug in SCHED_FEAT_SKIP_INITIAL (which
is disabled by default at the moment): it relies on se.wait_start_fair
being 0 while update_stats_wait_end() did not recognize a 0 value,
so instead of 'skipping' the initial interval we gave the new child
a maximum boost of +runtime-limit ...

(No impact on the default kernel, but nice to fix for completeness.)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
2007-08-28 12:53:24 +02:00
Ting Yang
7109c4429a sched: call update_curr() in task_tick_fair()
update the fair-clock before using it for the key value.

[ mingo@elte.hu: small cleanups. ]

Signed-off-by: Ting Yang <tingy@cs.umass.edu>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
2007-08-28 12:53:24 +02:00
Ingo Molnar
f6cf891c4d sched: make the scheduler converge to the ideal latency
de-HZ-ification of the granularity defaults unearthed a pre-existing
property of CFS: while it correctly converges to the granularity goal,
it does not prevent run-time fluctuations in the range of
[-gran ... 0 ... +gran].

With the increase of the granularity due to the removal of HZ
dependencies, this becomes visible in chew-max output (with 5 tasks
running):

 out:  28 . 27. 32 | flu:  0 .  0 | ran:    9 .   13 | per:   37 .   40
 out:  27 . 27. 32 | flu:  0 .  0 | ran:   17 .   13 | per:   44 .   40
 out:  27 . 27. 32 | flu:  0 .  0 | ran:    9 .   13 | per:   36 .   40
 out:  29 . 27. 32 | flu:  2 .  0 | ran:   17 .   13 | per:   46 .   40
 out:  28 . 27. 32 | flu:  0 .  0 | ran:    9 .   13 | per:   37 .   40
 out:  29 . 27. 32 | flu:  0 .  0 | ran:   18 .   13 | per:   47 .   40
 out:  28 . 27. 32 | flu:  0 .  0 | ran:    9 .   13 | per:   37 .   40

average slice is the ideal 13 msecs and the period is picture-perfect 40
msecs. But the 'ran' field fluctuates around 13.33 msecs and there's no
mechanism in CFS to keep that from happening: it's a perfectly valid
solution that CFS finds.

to fix this we add a granularity/preemption rule that knows about
the "target latency", which makes tasks that run longer than the ideal
latency run a bit less. The simplest approach is to simply decrease the
preemption granularity when a task overruns its ideal latency. For this
we have to track how much the task executed since its last preemption.

( this adds a new field to task_struct, but we can eliminate that
  overhead in 2.6.24 by putting all the scheduler timestamps into an
  anonymous union. )

with this change in place, chew-max output is fluctuation-less all
around:

 out:  28 . 27. 39 | flu:  0 .  2 | ran:   13 .   13 | per:   41 .   40
 out:  28 . 27. 39 | flu:  0 .  2 | ran:   13 .   13 | per:   41 .   40
 out:  28 . 27. 39 | flu:  0 .  2 | ran:   13 .   13 | per:   41 .   40
 out:  28 . 27. 39 | flu:  0 .  2 | ran:   13 .   13 | per:   41 .   40
 out:  28 . 27. 39 | flu:  0 .  1 | ran:   13 .   13 | per:   41 .   40
 out:  28 . 27. 39 | flu:  0 .  1 | ran:   13 .   13 | per:   41 .   40

this patch has no impact on any fastpath or on any globally observable
scheduling property. (unless you have sharp enough eyes to see
millisecond-level ruckles in glxgears smoothness :-)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
2007-08-28 12:53:24 +02:00
Mike Galbraith
5f01d519e6 sched: fix sleeper bonus limit
There is an Amarok song switch time increase (regression) under
hefty load.

What is happening is that sleeper_bonus is never consumed, and only
rarely goes below runtime_limit, so for the most part, Amarok isn't
getting any bonus at all.  We're keeping sleeper_bonus right at
runtime_limit (sched_latency == sched_runtime_limit == 40ms) forever, ie
we don't consume if we're lower that that, and don't add if we're above
it.  One Amarok thread waking (or anybody else) will push us past the
threshold, so the next thread waking gets nada, but will reap pain from
the previous thread waking until we drop back to runtime_limit.  It
looks to me like under load, some random task gets a bonus, and
everybody else pays, whether deserving or not.

This diff fixed the regression for me at any load rate.

Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
2007-08-28 12:53:24 +02:00
Ingo Molnar
172ac3dbb7 sched: cleanup, sched_granularity -> sched_min_granularity
due to adaptive granularity scheduling the role of sched_granularity
has changed to "minimum granularity", so rename the variable (and the
tunable) accordingly.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
2007-08-25 18:41:53 +02:00
Peter Zijlstra
218050855e sched: adaptive scheduler granularity
Instead of specifying the preemption granularity, specify the wanted
latency. By fixing the granlarity to a constany the wakeup latency
it a function of the number of running tasks on the rq.

Invert this relation.

sysctl_sched_granularity becomes a minimum for the dynamic granularity
computed from the new sysctl_sched_latency.

Then use this latency to do more intelligent granularity decisions: if
there are fewer tasks running then we can schedule coarser. This helps
performance while still always keeping the latency target.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-25 18:41:53 +02:00
Ingo Molnar
095e56c703 sched: fix startup penalty calculation
fix task startup penalty miscalculation: sysctl_sched_granularity is
unsigned int and wait_runtime is long so we first have to convert it
to long before turning it negative ...

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-24 20:39:10 +02:00
Peter Zijlstra
ea0aa3b23a sched: simplify bonus calculation #2
current code:

 delta = calc_delta_mine(delta_exec, curr->load.weight, lw);
 delta = min((u64)delta, cfs_rq->sleeper_bonus);

Notice that this calc_delta_mine() line is exactly delta_mine, which
gives:

 delta = min((u64)delta_mine, cfs_rq->sleeper_bonus);

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-24 20:39:10 +02:00
Peter Zijlstra
a6f2994042 sched: simplify bonus calculation #1
current code:

 delta = min(cfs_rq->sleeper_bonus, (u64)delta_exec);
 delta = calc_delta_mine(delta, curr->load.weight, lw);
 delta = min((u64)delta, cfs_rq->sleeper_bonus);

drop the first min(), because we clip against sleeper_bonus in the 3rd line
again. That gives:

 delta = calc_delta_mine(delta_exec, curr->load.weight, lw);
 delta = min((u64)delta, cfs_rq->sleeper_bonus);

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-24 20:39:10 +02:00
Ingo Molnar
b2133c8b1e sched: tidy up and simplify the bonus balance
make the bonus balance more consistent: do not hand out a bonus if
there's too much in flight already, and only deduct as much from a
runner as it has the capacity. This makes the bonus engine a zero-sum
game (as intended).

this also simplifies the code:

   text    data     bss     dec     hex filename
  34770    2998      24   37792    93a0 sched.o.before
  34749    2998      24   37771    938b sched.o.after

and it also avoids overscheduling in sleep-happy workloads like
hackbench.c.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-24 20:39:10 +02:00
Ingo Molnar
71fd371463 sched: remove HZ dependency from the granularity default
remove HZ dependency from the granularity default. Use 10 msec for
the base granularity, 1 msec for wakeup granularity and 25 msec for
batch wakeup granularity. (These defaults are close to the values
that the default HZ=250 setting got previously, and thus it's the
most common setting.)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-24 20:39:10 +02:00
Bruce Ashfield
7c6c16f354 sched: CONFIG_SCHED_GROUP_FAIR=y fixlet
when I built with CONFIG_FAIR_GROUP_SCHED=y, I need the following change
to make things right.

[ From: mingo@elte.hu ]

this config option is not upstream-configurable right now but lets fix
this for completeness.

Signed-off-by: Bruce Ashfield <bruce.ashfield@windriver.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-24 20:39:10 +02:00
Ingo Molnar
5d2b3d3695 sched: fix sleeper bonus
Peter Ziljstra noticed that the sleeper bonus deduction code
was not properly rate-limited: a task that scheduled more
frequently would get a disproportionately large deduction.
So limit the deduction to delta_exec.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-12 18:08:19 +02:00
Ingo Molnar
e56f31aad9 sched: fix typo in the FAIR_GROUP_SCHED branch
while there's no in-tree way to turn group scheduling at the moment,
fix a typo in it nevertheless.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-10 23:05:11 +02:00
Ingo Molnar
7cff8cf61c sched: refine negative nice level granularity
refine the granularity of negative nice level tasks: let them
reschedule more often to offset the effect of them consuming
their wait_runtime proportionately slower. (This makes nice-0
task scheduling smoother in the presence of negatively
reniced tasks.)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:52 +02:00
Ingo Molnar
a69edb5560 sched: fix update_stats_enqueue() reniced codepath
the key has to be rescaled to /weight even if it has a positive value.

(this change only affects the scheduling of reniced tasks)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:52 +02:00
Ingo Molnar
c3b64f1e4f sched: clean up set_curr_task_fair()
clean up set_curr_task_fair().

( identity transformation that causes no change in functionality. )

   text    data     bss     dec     hex filename
  39170    3750      36   42956    a7cc sched.o.before
  39170    3750      36   42956    a7cc sched.o.after

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:51 +02:00
Ingo Molnar
d9e0e6aa6d sched: remove __update_rq_clock() call from entity_tick()
remove __update_rq_clock() call from entity_tick().

no change in functionality because scheduler_tick() already calls
__update_rq_clock().

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:51 +02:00
Ingo Molnar
bdd4dfa89c sched: remove the 'u64 now' local variables
final step: remove all (now superfluous) 'u64 now' variables.

( identity transformation that causes no change in functionality. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:51 +02:00
Ingo Molnar
ee0827d8b5 sched: remove the 'u64 now' parameter from ->task_new()
remove the 'u64 now' parameter from ->task_new().

( identity transformation that causes no change in functionality. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:49 +02:00
Ingo Molnar
31ee529cc2 sched: remove the 'u64 now' parameter from ->put_prev_task()
remove the 'u64 now' parameter from ->put_prev_task().

( identity transformation that causes no change in functionality. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:49 +02:00
Ingo Molnar
fb8d472402 sched: remove the 'u64 now' parameter from ->pick_next_task()
remove the 'u64 now' parameter from ->pick_next_task().

( identity transformation that causes no change in functionality. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:48 +02:00
Ingo Molnar
f02231e51a sched: remove the 'u64 now' parameter from ->dequeue_task()
remove the 'u64 now' parameter from ->dequeue_task().

( identity transformation that causes no change in functionality. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:48 +02:00
Ingo Molnar
fd390f6a04 sched: remove the 'u64 now' parameter from ->enqueue_task()
remove the 'u64 now' parameter from ->enqueue_task().

( identity transformation that causes no change in functionality. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:48 +02:00
Ingo Molnar
ab6cde2692 sched: remove the 'u64 now' parameter from put_prev_entity()
remove the 'u64 now' parameter from put_prev_entity().

( identity transformation that causes no change in functionality. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:48 +02:00
Ingo Molnar
9948f4b2a7 sched: remove the 'u64 now' parameter from pick_next_entity()
remove the 'u64 now' parameter from pick_next_entity().

( identity transformation that causes no change in functionality. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:48 +02:00
Ingo Molnar
8494f412ed sched: remove the 'u64 now' parameter from set_next_entity()
remove the 'u64 now' parameter from set_next_entity().

( identity transformation that causes no change in functionality. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:48 +02:00
Ingo Molnar
525c2716a4 sched: remove the 'u64 now' parameter from dequeue_entity()
remove the 'u64 now' parameter from dequeue_entity().

( identity transformation that causes no change in functionality. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:48 +02:00
Ingo Molnar
668031ca8f sched: remove the 'u64 now' parameter from enqueue_entity()
remove the 'u64 now' parameter from enqueue_entity().

( identity transformation that causes no change in functionality. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:48 +02:00
Ingo Molnar
2396af69be sched: remove the 'u64 now' parameter from enqueue_sleeper()
remove the 'u64 now' parameter from enqueue_sleeper().

( identity transformation that causes no change in functionality. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:48 +02:00
Ingo Molnar
dfdc119e54 sched: remove the 'u64 now' parameter from __enqueue_sleeper()
remove the 'u64 now' parameter from __enqueue_sleeper().

( identity transformation that causes no change in functionality. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:48 +02:00
Ingo Molnar
c7e9b5b293 sched: remove the 'u64 now' parameter from update_stats_curr_end()
remove the 'u64 now' parameter from update_stats_curr_end().

( identity transformation that causes no change in functionality. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:48 +02:00
Ingo Molnar
19b6a2e370 sched: remove the 'u64 now' parameter from update_stats_dequeue()
remove the 'u64 now' parameter from update_stats_dequeue().

( identity transformation that causes no change in functionality. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:48 +02:00
Ingo Molnar
79303e9e02 sched: remove the 'u64 now' parameter from update_stats_curr_start()
remove the 'u64 now' parameter from update_stats_curr_start().

( identity transformation that causes no change in functionality. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:47 +02:00
Ingo Molnar
9ef0a9615b sched: remove the 'u64 now' parameter from update_stats_wait_end()
remove the 'u64 now' parameter from update_stats_wait_end().

( identity transformation that causes no change in functionality. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:47 +02:00
Ingo Molnar
eac55ea376 sched: remove the 'u64 now' parameter from __update_stats_wait_end()
remove the 'u64 now' parameter from __update_stats_wait_end().

( identity transformation that causes no change in functionality. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:47 +02:00
Ingo Molnar
d2417e5a3e sched: remove the 'u64 now' parameter from update_stats_enqueue()
remove the 'u64 now' parameter from update_stats_enqueue().

( identity transformation that causes no change in functionality. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:47 +02:00
Ingo Molnar
5870db5b83 sched: remove the 'u64 now' parameter from update_stats_wait_start()
remove the 'u64 now' parameter from update_stats_wait_start().

( identity transformation that causes no change in functionality. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:47 +02:00
Ingo Molnar
b7cc089657 sched: remove the 'u64 now' parameter from update_curr()
remove the 'u64 now' parameter from update_curr().

( identity transformation that causes no change in functionality. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:47 +02:00
Ingo Molnar
5cef9eca38 sched: remove the 'u64 now' parameter from print_cfs_rq()
remove the 'u64 now' parameter from print_cfs_rq().

( identity transformation that causes no change in functionality. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:47 +02:00
Ingo Molnar
d281918d7c sched: remove 'now' use from assignments
change all 'now' timestamp uses in assignments to rq->clock.

( this is an identity transformation that causes no functionality change:
  all such new rq->clock is necessarily preceded by an update_rq_clock()
  call. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:47 +02:00
Ingo Molnar
c1b3da3ecd sched: eliminate __rq_clock() use
eliminate __rq_clock() use by changing it to:

   __update_rq_clock(rq)
   now = rq->clock;

identity transformation - no change in behavior.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:47 +02:00
Ingo Molnar
a8e504d2a5 sched: eliminate rq_clock() use
eliminate rq_clock() use by changing it to:

   update_rq_clock(rq)
   now = rq->clock;

identity transformation - no change in behavior.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:47 +02:00
Peter Williams
a4ac01c36e sched: fix bug in balance_tasks()
There are two problems with balance_tasks() and how it used:

1. The variables best_prio and best_prio_seen (inherited from the old
move_tasks()) were only required to handle problems caused by the
active/expired arrays, the order in which they were processed and the
possibility that the task with the highest priority could be on either.
  These issues are no longer present and the extra overhead associated
with their use is unnecessary (and possibly wrong).

2. In the absence of CONFIG_FAIR_GROUP_SCHED being set, the same
this_best_prio variable needs to be used by all scheduling classes or
there is a risk of moving too much load.  E.g. if the highest priority
task on this at the beginning is a fairly low priority task and the rt
class migrates a task (during its turn) then that moved task becomes the
new highest priority task on this_rq but when the sched_fair class
initializes its copy of this_best_prio it will get the priority of the
original highest priority task as, due to the run queue locks being
held, the reschedule triggered by pull_task() will not have taken place.
  This could result in inappropriate overriding of skip_for_load and
excessive load being moved.

The attached patch addresses these problems by deleting all reference to
best_prio and best_prio_seen and making this_best_prio a reference
parameter to the various functions involved.

load_balance_fair() has also been modified so that this_best_prio is
only reset (in the loop) if CONFIG_FAIR_GROUP_SCHED is set.  This should
preserve the effect of helping spread groups' higher priority tasks
around the available CPUs while improving system performance when
CONFIG_FAIR_GROUP_SCHED isn't set.

Signed-off-by: Peter Williams <pwil3058@bigpond.net.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:46 +02:00
Ingo Molnar
fd8bb43e27 sched: delta_exec accounting fix
small delta_exec accounting fix: increase delta_exec and increase
sum_exec_runtime even if the task is not on the runqueue anymore.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:46 +02:00
Ingo Molnar
c5dcfe72aa sched: clean up delta_mine
cleanup: delta_mine is an unsigned value.

no code impact:

   text    data     bss     dec     hex filename
   27823    2726      16   30565    7765 sched.o.before
   27823    2726      16   30565    7765 sched.o.after

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:46 +02:00
Josh Triplett
291ae5a120 sched: mark print_cfs_stats static
sched_fair.c defines print_cfs_stats, and sched_debug.c uses it, but sched.c
includes both sched_fair.c and sched_debug.c, so all the references to
print_cfs_stats occur in the same compilation unit.  Thus, mark
print_cfs_stats static.

Eliminates a sparse warning:
warning: symbol 'print_cfs_stats' was not declared. Should it be static?

Signed-off-by: Josh Triplett <josh@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:46 +02:00
Peter Williams
4301065920 sched: simplify move_tasks()
The move_tasks() function is currently multiplexed with two distinct
capabilities:

1. attempt to move a specified amount of weighted load from one run
queue to another; and
2. attempt to move a specified number of tasks from one run queue to
another.

The first of these capabilities is used in two places, load_balance()
and load_balance_idle(), and in both of these cases the return value of
move_tasks() is used purely to decide if tasks/load were moved and no
notice of the actual number of tasks moved is taken.

The second capability is used in exactly one place,
active_load_balance(), to attempt to move exactly one task and, as
before, the return value is only used as an indicator of success or failure.

This multiplexing of sched_task() was introduced, by me, as part of the
smpnice patches and was motivated by the fact that the alternative, one
function to move specified load and one to move a single task, would
have led to two functions of roughly the same complexity as the old
move_tasks() (or the new balance_tasks()).  However, the new modular
design of the new CFS scheduler allows a simpler solution to be adopted
and this patch addresses that solution by:

1. adding a new function, move_one_task(), to be used by
active_load_balance(); and
2. making move_tasks() a single purpose function that tries to move a
specified weighted load and returns 1 for success and 0 for failure.

One of the consequences of these changes is that neither move_one_task()
or the new move_tasks() care how many tasks sched_class.load_balance()
moves and this enables its interface to be simplified by returning the
amount of load moved as its result and removing the load_moved pointer
from the argument list.  This helps simplify the new move_tasks() and
slightly reduces the amount of work done in each of
sched_class.load_balance()'s implementations.

Further simplification, e.g. changes to balance_tasks(), are possible
but (slightly) complicated by the special needs of load_balance_fair()
so I've left them to a later patch (if this one gets accepted).

NB Since move_tasks() gets called with two run queue locks held even
small reductions in overhead are worthwhile.

[ mingo@elte.hu ]

this change also reduces code size nicely:

   text    data     bss     dec     hex filename
   39216    3618      24   42858    a76a sched.o.before
   39173    3618      24   42815    a73f sched.o.after

Signed-off-by: Peter Williams <pwil3058@bigpond.net.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:46 +02:00
Ingo Molnar
0915c4e89d sched: batch sleeper bonus
batch up the sleeper bonus sum a bit more. Anything below
sched-granularity is too small to make a practical difference
anyway.

this optimization reduces the math in high-frequency scheduling
scenarios.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:45 +02:00
Ingo Molnar
6cfb0d5d06 [PATCH] sched: reduce debug code
move the rest of the debugging/instrumentation code to under
CONFIG_SCHEDSTATS too. This reduces code size and speeds code up:

    text    data     bss     dec     hex filename
   33044    4122      28   37194    914a sched.o.before
   32708    4122      28   36858    8ffa sched.o.after

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-02 17:41:40 +02:00