Refuse to accept or create RT tasks in groups that can't run them.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Clean up some of the excessive ifdeffery introduces in the last patch.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Make the rt group scheduler compile time configurable.
Keep it experimental for now.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Change the rt_ratio interface to rt_runtime_us, to match rt_period_us.
This avoids picking a granularity for the ratio.

Extend the /sys/kernel/uids/<uid>/ interface to allow setting
the group's rt_runtime.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Steven mentioned the fun case where a lock holding task will be throttled.

Simple fix: allow groups that have boosted tasks to run anyway.

If a runnable task in a throttled group gets boosted the dequeue/enqueue
done by rt_mutex_setprio() is enough to unthrottle the group.

This is ofcourse not quite correct. Two possible ways forward are:
  - second prio array for boosted tasks
  - boost to a prio ceiling (this would also work for deadline scheduling)

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

lockdep spotted this bogus irq locking. normalize_rt_tasks() can be called
from hardirq context through sysrq-n

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

On Mon, 2008-02-11 at 15:09 +0300, Denis V. Lunev wrote:
> BUG: sleeping function called from invalid context
> at /home/den/src/linux-netns26/kernel/mutex.c:209
> in_atomic():1, irqs_disabled():0
> no locks held by swapper/0.
> Pid: 0, comm: swapper Not tainted 2.6.24 #304
>
> Call Trace:
>  <IRQ>  [<ffffffff80252d1e>] ? __debug_show_held_locks+0x15/0x27
>  [<ffffffff8022c2a8>] __might_sleep+0xc0/0xdf
>  [<ffffffff8049f1df>] mutex_lock_nested+0x28/0x2a9
>  [<ffffffff80231294>] sched_destroy_group+0x18/0xea
>  [<ffffffff8023e835>] sched_destroy_user+0xd/0xf
>  [<ffffffff8023e8c1>] free_uid+0x8a/0xab
>  [<ffffffff80233e24>] __put_task_struct+0x3f/0xd3
>  [<ffffffff80236708>] delayed_put_task_struct+0x23/0x25
>  [<ffffffff8026fda7>] __rcu_process_callbacks+0x8d/0x215
>  [<ffffffff8026ff52>] rcu_process_callbacks+0x23/0x44
>  [<ffffffff8023a2ae>] __do_softirq+0x79/0xf8
>  [<ffffffff8020f8c3>] ? profile_pc+0x2a/0x67
>  [<ffffffff8020d38c>] call_softirq+0x1c/0x30
>  [<ffffffff8020f689>] do_softirq+0x61/0x9c
>  [<ffffffff8023a233>] irq_exit+0x51/0x53
>  [<ffffffff8021bd1a>] smp_apic_timer_interrupt+0x77/0xad
>  [<ffffffff8020ce3b>] apic_timer_interrupt+0x6b/0x70
>  <EOI>  [<ffffffff8020b0dd>] ? default_idle+0x43/0x76
>  [<ffffffff8020b0db>] ? default_idle+0x41/0x76
>  [<ffffffff8020b09a>] ? default_idle+0x0/0x76
>  [<ffffffff8020b186>] ? cpu_idle+0x76/0x98

separate the tg->shares protection from the task_group lock.

Reported-by: Denis V. Lunev <den@openvz.org>
Tested-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

* 'task_killable' of git://git.kernel.org/pub/scm/linux/kernel/git/willy/misc: (22 commits)
  Remove commented-out code copied from NFS
  NFS: Switch from intr mount option to TASK_KILLABLE
  Add wait_for_completion_killable
  Add wait_event_killable
  Add schedule_timeout_killable
  Use mutex_lock_killable in vfs_readdir
  Add mutex_lock_killable
  Use lock_page_killable
  Add lock_page_killable
  Add fatal_signal_pending
  Add TASK_WAKEKILL
  exit: Use task_is_*
  signal: Use task_is_*
  sched: Use task_contributes_to_load, TASK_ALL and TASK_NORMAL
  ptrace: Use task_is_*
  power: Use task_is_*
  wait: Use TASK_NORMAL
  proc/base.c: Use task_is_*
  proc/array.c: Use TASK_REPORT
  perfmon: Use task_is_*
  ...

Fixed up conflicts in NFS/sunrpc manually..

This removes the extra struct task_struct *p parameter in inc_nr_running
and dec_nr_running functions.

Signed-off by: Jerry Stralko <gerb.stralko@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>