'777c6c5f wait: prevent exclusive waiter starvation' made
__wake_up_common() global to be used from abort_exclusive_wait().

It was needed to do a wake-up with the waitqueue lock held while
passing down a key to the wake-up function.

Since '4ede816a epoll keyed wakeups: add __wake_up_locked_key() and
__wake_up_sync_key()' there is an appropriate wrapper for this case:
__wake_up_locked_key().

Use it here and make __wake_up_common() private to the scheduler
again.
Signed-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1239720785-19661-1-git-send-email-hannes@cmpxchg.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The CPU that first goes idle becomes the idle-load-balancer and remains
that until either it picks up a task or till all the CPUs of the system
goes idle.

Optimize this further to allow it to relinquish it's post
once all it's siblings in the power-aware sched_domain go idle, thereby
allowing the whole package-core to go idle. While relinquising the post,
nominate another an idle-load balancer from a semi-idle core/package.
Signed-off-by: NGautham R Shenoy <ego@in.ibm.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20090414045535.7645.31641.stgit@sofia.in.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Currently the nomination of idle-load balancer is done by choosing the first
idle cpu in the nohz.cpu_mask. This may not be power-efficient, since
such an idle cpu could come from a completely idle core/package thereby
preventing the whole core/package from being in a low-power state.

For eg, consider a quad-core dual package system. The cpu numbering need
not be sequential and can something like [0, 2, 4, 6] and [1, 3, 5, 7].
With sched_mc/smt_power_savings and the power-aware IRQ balance, we try to keep
as fewer Packages/Cores active. But the current idle load balancer logic
goes against this by choosing the first_cpu in the nohz.cpu_mask and not
taking the system topology into consideration.

Improve the algorithm to nominate the idle load balancer from a semi idle
cores/packages thereby increasing the probability of the cores/packages being
in deeper sleep states for longer duration.

The algorithm is activated only when sched_mc/smt_power_savings != 0.
Signed-off-by: NGautham R Shenoy <ego@in.ibm.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20090414045530.7645.12175.stgit@sofia.in.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

This patchset introduces wakeup hints for some of the most popular (from
epoll POV) devices, so that epoll code can avoid spurious wakeups on its
waiters.

The problem with epoll is that the callback-based wakeups do not, ATM,
carry any information about the events the wakeup is related to.  So the
only choice epoll has (not being able to call f_op->poll() from inside the
callback), is to add the file* to a ready-list and resolve the real events
later on, at epoll_wait() (or its own f_op->poll()) time.  This can cause
spurious wakeups, since the wake_up() itself might be for an event the
caller is not interested into.

The rate of these spurious wakeup can be pretty high in case of many
network sockets being monitored.

By allowing devices to report the events the wakeups refer to (at least
the two major classes - POLLIN/POLLOUT), we are able to spare useless
wakeups by proper handling inside the epoll's poll callback.

Epoll will have in any case to call f_op->poll() on the file* later on,
since the change to be done in order to have the full event set sent via
wakeup, is too invasive for the way our f_op->poll() system works (the
full event set is calculated inside the poll function - there are too many
of them to even start thinking the change - also poll/select would need
change too).

Epoll is changed in a way that both devices which send event hints, and
the ones that don't, are correctly handled.  The former will gain some
efficiency though.

As a general rule for devices, would be to add an event mask by using
key-aware wakeup macros, when making up poll wait queues.  I tested it
(together with the epoll's poll fix patch Andrew has in -mm) and wakeups
for the supported devices are correctly filtered.

Test program available here:

http://www.xmailserver.org/epoll_test.c

This patch:

Nothing revolutionary here.  Just using the available "key" that our
wakeup core already support.  The __wake_up_locked_key() was no brainer,
since both __wake_up_locked() and __wake_up_locked_key() are thin wrappers
around __wake_up_common().

The __wake_up_sync() function had a body, so the choice was between
borrowing the body for __wake_up_sync_key() and calling it from
__wake_up_sync(), or make an inline and calling it from both.  I chose the
former since in most archs it all resolves to "mov $0, REG; jmp ADDR".
Signed-off-by: NDavide Libenzi <davidel@xmailserver.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: David Miller <davem@davemloft.net>
Cc: William Lee Irwin III <wli@movementarian.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Impact: extend debug info /proc/sched_debug

If the user changes the value of the sched_mc/smt_power_savings sysfs
tunable, it'll trigger a rebuilding of the whole sched_domain tree,
with the SD_POWERSAVINGS_BALANCE flag set at certain levels.

As a result, there would be a change in the __cpu_power of sched_groups
in the sched_domain hierarchy.

Print the __cpu_power values for each sched_group in sched_domain_debug
to help verify this change and correlate it with the change in the
load-balancing behavior.
Signed-off-by: NGautham R Shenoy <ego@in.ibm.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20090330045520.2869.24777.stgit@sofia.in.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Add per-cgroup cpuacct controller statistics like the system and user
time consumed by the group of tasks.

Changelog:

v7
- Changed the name of the statistic from utime to user and from stime to
  system so that in future we could easily add other statistics like irq,
  softirq, steal times etc easily.

v6
- Fixed a bug in the error path of cpuacct_create() (pointed by Li Zefan).

v5
- In cpuacct_stats_show(), use cputime64_to_clock_t() since we are
  operating on a 64bit variable here.

v4
- Remove comments in cpuacct_update_stats() which explained why rcu_read_lock()
  was needed (as per Peter Zijlstra's review comments).
- Don't say that percpu_counter_read() is broken in Documentation/cpuacct.txt
  as per KAMEZAWA Hiroyuki's review comments.

v3
- Fix a small race in the cpuacct hierarchy walk.

v2
- stime and utime now exported in clock_t units instead of msecs.
- Addressed the code review comments from Balbir and Li Zefan.
- Moved to -tip tree.

v1
- Moved the stime/utime accounting to cpuacct controller.

Earlier versions
- http://lkml.org/lkml/2009/2/25/129Signed-off-by: NBharata B Rao <bharata@linux.vnet.ibm.com>
Signed-off-by: NBalaji Rao <balajirrao@gmail.com>
Cc: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Cc: Paul Menage <menage@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: NLi Zefan <lizf@cn.fujitsu.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: NBalbir Singh <balbir@linux.vnet.ibm.com>
Tested-by: NBalbir Singh <balbir@linux.vnet.ibm.com>
LKML-Reference: <20090331043222.GA4093@in.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: Regression fix (against clock_gettime() backwarding bug)

This patch re-introduces a couple of functions, task_sched_runtime
and thread_group_sched_runtime, which was once removed at the
time of 2.6.28-rc1.

These functions protect the sampling of thread/process clock with
rq lock.  This rq lock is required not to update rq->clock during
the sampling.

i.e.
  The clock_gettime() may return
   ((accounted runtime before update) + (delta after update))
  that is less than what it should be.

v2 -> v3:
	- Rename static helper function __task_delta_exec()
	  to do_task_delta_exec() since -tip tree already has
	  a __task_delta_exec() of different version.

v1 -> v2:
	- Revises comments of function and patch description.
	- Add note about accuracy of thread group's runtime.
Signed-off-by: NHidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: stable@kernel.org	[2.6.28.x][2.6.29.x]
LKML-Reference: <49D1CC93.4080401@jp.fujitsu.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: fix cgroups race under rcu-preempt

cpuacct_charge() obtains task's ca and does a hierarchy walk upwards.
This can race with the task's movement between cgroups. This race
can cause an access to freed ca pointer in cpuacct_charge() or access
to invalid cgroups pointer of the task. This will not happen with rcu or
tree rcu as cpuacct_charge() is called with preemption disabled. However if
rcupreempt is used, the race is seen. Thanks to Li Zefan for explaining this.

Fix this race by explicitly protecting ca and the hierarchy walk with
rcu_read_lock().

Changes for v2:

 - Update patch descrition (as per Li Zefan's review comments).

 - Remove comments in cpuacct_charge() which explained why rcu_read_lock()
   was needed (as per Peter Zijlstra's review comments).
Signed-off-by: NBharata B Rao <bharata@linux.vnet.ibm.com>
Cc: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: NBalbir Singh <balbir@linux.vnet.ibm.com>
Tested-by: NBalbir Singh <balbir@linux.vnet.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

It appears I inadvertly introduced rq->lock recursion to the
hrtimer_start() path when I delegated running already expired
timers to softirq context.

This patch fixes it by introducing a __hrtimer_start_range_ns()
method that will not use raise_softirq_irqoff() but
__raise_softirq_irqoff() which avoids the wakeup.

It then also changes schedule() to check for pending softirqs and
do the wakeup then, I'm not quite sure I like this last bit, nor
am I convinced its really needed.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: paulus@samba.org
LKML-Reference: <20090313112301.096138802@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

This reverts commit 7a46c594.

This was applied to the x86 tree mistakenly, it belongs into the
scheduler tree.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Fix kernel-doc errors in sched.c:  the structs don't have
kernel-doc notation and the short function description needs to
be one line only.

  Error(kernel/sched.c:3197): cannot understand prototype: 'struct sd_lb_stats '
  Error(kernel/sched.c:3228): cannot understand prototype: 'struct sg_lb_stats '
  Error(kernel/sched.c:3375): duplicate section name 'Description'
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Impact: cleanup

Add /** style comments around find_busiest_group(). Also add a few
explanatory comments.

This concludes the find_busiest_group() cleanup. The function is
now down to 72 lines from the original 313 lines.
Signed-off-by: NGautham R Shenoy <ego@in.ibm.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: "Balbir Singh" <balbir@in.ibm.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: "Dhaval Giani" <dhaval@linux.vnet.ibm.com>
Cc: Bharata B Rao <bharata@linux.vnet.ibm.com>
Cc: "Vaidyanathan Srinivasan" <svaidy@linux.vnet.ibm.com>
LKML-Reference: <20090325091427.13992.18933.stgit@sofia.in.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup

Create seperate helper functions to initialize the
power-savings-balance related variables, to update them and
to check if we have a scope for performing power-savings balance.

Add no-op inline functions for the !(CONFIG_SCHED_MC || CONFIG_SCHED_SMT)
case.

This will eliminate all the #ifdef jungle in find_busiest_group() and the
other helper functions.
Signed-off-by: NGautham R Shenoy <ego@in.ibm.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: "Balbir Singh" <balbir@in.ibm.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: "Dhaval Giani" <dhaval@linux.vnet.ibm.com>
Cc: Bharata B Rao <bharata@linux.vnet.ibm.com>
Cc: "Vaidyanathan Srinivasan" <svaidy@linux.vnet.ibm.com>
LKML-Reference: <20090325091422.13992.73616.stgit@sofia.in.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup, micro-optimization

We don't need to perform power_savings balance if either the
cpu is NOT_IDLE or if the sched_domain doesn't contain the
SD_POWERSAVINGS_BALANCE flag set.

Currently, we check for these conditions multiple number of
times, even though these variables don't change over the scope
of find_busiest_group().

Check once, and store the value in the already exiting
"power_savings_balance" variable.
Signed-off-by: NGautham R Shenoy <ego@in.ibm.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: "Balbir Singh" <balbir@in.ibm.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: "Dhaval Giani" <dhaval@linux.vnet.ibm.com>
Cc: Bharata B Rao <bharata@linux.vnet.ibm.com>
Cc: "Vaidyanathan Srinivasan" <svaidy@linux.vnet.ibm.com>
LKML-Reference: <20090325091417.13992.2657.stgit@sofia.in.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Move all the imbalance calculation out of find_busiest_group()
through this helper function.

With this change, the structure of find_busiest_group() will be
as follows:

- update_sched_domain_statistics.

- check if imbalance exits.

- update imbalance and return busiest.
Signed-off-by: NGautham R Shenoy <ego@in.ibm.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: "Balbir Singh" <balbir@in.ibm.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: "Dhaval Giani" <dhaval@linux.vnet.ibm.com>
Cc: Bharata B Rao <bharata@linux.vnet.ibm.com>
Cc: "Vaidyanathan Srinivasan" <svaidy@linux.vnet.ibm.com>
LKML-Reference: <20090325091411.13992.43293.stgit@sofia.in.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup

We have two places in find_busiest_group() where we need to calculate
the minor imbalance before returning the busiest group. Encapsulate
this functionality into a seperate helper function.

Credit: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Signed-off-by: NGautham R Shenoy <ego@in.ibm.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: "Balbir Singh" <balbir@in.ibm.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: "Dhaval Giani" <dhaval@linux.vnet.ibm.com>
Cc: Bharata B Rao <bharata@linux.vnet.ibm.com>
LKML-Reference: <20090325091406.13992.54316.stgit@sofia.in.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup

Create a helper function named update_sd_lb_stats() to update the
various sched_domain related statistics in find_busiest_group().

With this we would have moved all the statistics computation out of
find_busiest_group().

Credit: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Signed-off-by: NGautham R Shenoy <ego@in.ibm.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: "Balbir Singh" <balbir@in.ibm.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: "Dhaval Giani" <dhaval@linux.vnet.ibm.com>
Cc: Bharata B Rao <bharata@linux.vnet.ibm.com>
LKML-Reference: <20090325091401.13992.88737.stgit@sofia.in.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup

Currently we use a lot of local variables in find_busiest_group()
to capture the various statistics related to the sched_domain.
Group them together into a single data structure.

This will help us to offload the job of updating the sched_domain
statistics to a helper function.

Credit: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Signed-off-by: NGautham R Shenoy <ego@in.ibm.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: "Balbir Singh" <balbir@in.ibm.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: "Dhaval Giani" <dhaval@linux.vnet.ibm.com>
Cc: Bharata B Rao <bharata@linux.vnet.ibm.com>
LKML-Reference: <20090325091356.13992.25970.stgit@sofia.in.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup

Create a helper function named update_sg_lb_stats() which
can be invoked to calculate the individual group's statistics
in find_busiest_group().

This reduces the lenght of find_busiest_group() considerably.

Credit: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Signed-off-by: NGautham R Shenoy <ego@in.ibm.com>
Aked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: "Balbir Singh" <balbir@in.ibm.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: "Dhaval Giani" <dhaval@linux.vnet.ibm.com>
Cc: Bharata B Rao <bharata@linux.vnet.ibm.com>
LKML-Reference: <20090325091351.13992.43461.stgit@sofia.in.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup

Currently a whole bunch of variables are used to store the
various statistics pertaining to the groups we iterate over
in find_busiest_group().

Group them together in a single data structure and add
appropriate comments.

This will be useful later on when we create helper functions
to calculate the sched_group statistics.

Credit: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Signed-off-by: NGautham R Shenoy <ego@in.ibm.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: "Balbir Singh" <balbir@in.ibm.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: "Dhaval Giani" <dhaval@linux.vnet.ibm.com>
Cc: Bharata B Rao <bharata@linux.vnet.ibm.com>
LKML-Reference: <20090325091345.13992.20099.stgit@sofia.in.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup

Some indentations in find_busiest_group() can minimized by using
early exits with the help of gotos. This improves readability in
a couple of cases.
Signed-off-by: NGautham R Shenoy <ego@in.ibm.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: "Balbir Singh" <balbir@in.ibm.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: "Dhaval Giani" <dhaval@linux.vnet.ibm.com>
Cc: Bharata B Rao <bharata@linux.vnet.ibm.com>
Cc: "Vaidyanathan Srinivasan" <svaidy@linux.vnet.ibm.com>
LKML-Reference: <20090325091340.13992.45062.stgit@sofia.in.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup

Currently the load idx calculation code is in find_busiest_group().
Move that to a static inline helper function.

Similary, to find the first cpu of a sched_group we use
cpumask_first(sched_group_cpus(group))

Use a helper to that. It improves readability in some cases.
Signed-off-by: NGautham R Shenoy <ego@in.ibm.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: "Balbir Singh" <balbir@in.ibm.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: "Dhaval Giani" <dhaval@linux.vnet.ibm.com>
Cc: Bharata B Rao <bharata@linux.vnet.ibm.com>
Cc: "Vaidyanathan Srinivasan" <svaidy@linux.vnet.ibm.com>
LKML-Reference: <20090325091335.13992.55424.stgit@sofia.in.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup, new schedstat ABI

Since they are used on in statistics and are always set to zero, the
following fields from struct rq have been removed: yld_exp_empty,
yld_act_empty and yld_both_empty.

Both Sched Debug and SCHEDSTAT_VERSION versions has also been
incremented since ABIs have been changed.

The schedtop tool has been updated to properly handle new version of
schedstat:

   http://rt.wiki.kernel.org/index.php/Schedtop_utilitySigned-off-by: NLuis Henriques <henrix@sapo.pt>
Acked-by: NGregory Haskins <ghaskins@novell.com>
Acked-by: NPeter Zijlstra <peterz@infradead.org>
LKML-Reference: <20090324221002.GA10061@hades.domain.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: fix boot crash

Fix typo in the size calculation.
Reported-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
LKML-Reference: <alpine.DEB.2.00.0903181729360.31583@gandalf.stny.rr.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: fix circular locking

Steven reports a circular locking from alloc_cpumask_var doing
a wakeup. We get rid of this using the tried-and-true technique
of using a per-cpu cpumask_var_t rather than doing an alloc
every time.

Simpler and more robust than a rare, implicit allocation within
an atomic codepath.
Reported-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
LKML-Reference: <alpine.DEB.2.00.0903181729360.31583@gandalf.stny.rr.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

There were 3 invocations of task_hot() in can_migrate_task().

Replace these 3 invocations by only one invocation, cached in
a local variable.
Signed-off-by: NLuis Henriques <henrix@sapo.pt>
LKML-Reference: <20090316195902.GA6197@hades.domain.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Fixed typos in function documentation.
Signed-off-by: NLuis Henriques <henrix@sapo.pt>
LKML-Reference: <20090316195809.GA6073@hades.domain.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup

This is presumably what those definitions are for, and while all archs
define cpu_core_map/cpu_sibling map, that's changing (eg. x86 wants to
change it to a pointer).
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Impact: micro-optimization

In cpuacct_charge(), task_ca() will never return NULL, so change
for(...) to do { } while(...) to save one NULL check.
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Menage <menage@google.com>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Bharata B Rao <bharata@linux.vnet.ibm.com>
LKML-Reference: <49B863F5.2060400@cn.fujitsu.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: more precise avg_overlap metric - better load-balancing

avg_overlap is used to measure the runtime overlap of the waker and
wakee.

However, when a process changes behaviour, eg a pipe becomes
un-congested and we don't need to go to sleep after a wakeup
for a while, the avg_overlap value grows stale.

When running we use the avg runtime between preemption as a
measure for avg_overlap since the amount of runtime can be
correlated to cache footprint.

The longer we run, the less likely we'll be wanting to be
migrated to another CPU.
Signed-off-by: NMike Galbraith <efault@gmx.de>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1236709131.25234.576.camel@laptop>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: micro-optimization

We can avoid the sched domain walk on try_to_wake_up() when we know
there are no groups.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1236603381.8389.455.camel@laptop>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup

Use test_tsk_need_resched(), set_tsk_need_resched(), need_resched()
instead of using TIF_NEED_RESCHED.
Signed-off-by: NLai Jiangshan <laijs@cn.fujitsu.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <49B10BA4.9070209@cn.fujitsu.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: fix function graph trace hang / drop pointless softirq on UP

While debugging a function graph trace hang on an old PII, I saw
that it consumed most of its time on the timer interrupt. And
the domain rebalancing softirq was the most concerned.

The timer interrupt calls trigger_load_balance() which will
decide if it is worth to schedule a rebalancing softirq.

In case of builtin UP kernel, no problem arises because there is
no domain question.

In case of builtin SMP kernel running on an SMP box, still no
problem, the softirq will be raised each time we reach the
next_balance time.

In case of builtin SMP kernel running on a UP box (most distros
provide default SMP kernels, whatever the box you have), then
the CPU is attached to the NULL sched domain. So a kind of
unexpected behaviour happen:

trigger_load_balance() -> raises the rebalancing softirq later
on softirq: run_rebalance_domains() -> rebalance_domains() where
the for_each_domain(cpu, sd) is not taken because of the NULL
domain we are attached at. Which means rq->next_balance is never
updated. So on the next timer tick, we will enter
trigger_load_balance() which will always reschedule() the
rebalacing softirq:

if (time_after_eq(jiffies, rq->next_balance))
	raise_softirq(SCHED_SOFTIRQ);

So for each tick, we process this pointless softirq.

This patch fixes it by checking if we are attached to the null
domain before raising the softirq, another possible fix would be
to set the maximal possible JIFFIES value to rq->next_balance if
we are attached to the NULL domain.

v2: build fix on UP
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <49af242d.1c07d00a.32d5.ffffc019@mx.google.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: micro-optimization

Parameter "prev" is not used really.
Signed-off-by: NWang Chen <wangchen@cn.fujitsu.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: fix hung task with certain (non-default) rt-limit settings

Corey Hickey reported that on using setuid to change the uid of a
rt process, the process would be unkillable and not be running.
This is because there was no rt runtime for that user group. Add
in a check to see if a user can attach an rt task to its task group.
On failure, return EINVAL, which is also returned in
CONFIG_CGROUP_SCHED.
Reported-by: NCorey Hickey <bugfood-ml@fatooh.org>
Signed-off-by: NDhaval Giani <dhaval@linux.vnet.ibm.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: fix incorrect condition check

No need to start rt bandwidth timer when rt bandwidth is disabled.
If this timer starts, it may stop at sched_rt_period_timer() on the first time.
Signed-off-by: NHiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

cpuacct_charge() is in fast-path, and checking of !cpuacct_susys.active
always returns false after cpuacct has been initialized at system boot.
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Menage <menage@google.com>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Oleg noticed that we don't strictly need CSD_FLAG_WAIT, rework
the code so that we can use CSD_FLAG_LOCK for both purposes.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup

There are two allocated per-cpu accessor macros with almost identical
spelling.  The original and far more popular is per_cpu_ptr (44
files), so change over the other 4 files.

tj: kill percpu_ptr() and update UP too
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
Cc: mingo@redhat.com
Cc: lenb@kernel.org
Cc: cpufreq@vger.kernel.org
Signed-off-by: NTejun Heo <tj@kernel.org>

#define TASK_NICE(p)            PRIO_TO_NICE((p)->static_prio)

So it's better to use TASK_NICE here.
Signed-off-by: NWANG Cong <wangcong@zeuux.org>
Acked-by: NPeter Zijlstra <peterz@infradead.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>