make sure sync wakeups preempt too - the scheduler will not
overschedule as we've got various throttles against that.
As a result, sync wakeups can be used more widely in the kernel
(to signal wakeup affinity between tasks), and no arbitrary
latencies will be introduced either.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

make sync wakeups affine for cache-cold tasks: if a cache-cold task
is woken up by a sync wakeup then use the opportunity to migrate it
straight away. (the two tasks are 'related' because they communicate)
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Modify KVM to update guest time accounting.

[ mingo@elte.hu: ported to 2.6.24 KVM. ]
Signed-off-by: NLaurent Vivier <Laurent.Vivier@bull.net>
Acked-by: NAvi Kivity <avi@qumranet.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

modify account_system_time() to add cputime to cpustat->guest if we are
running a VCPU. We add this cputime to cpustat->user instead of
cpustat->system because this part of KVM code is in fact user code
although it is executed in the kernel. We duplicate VCPU time between
guest and user to allow an unmodified "top(1)" to display correct value.
A modified "top(1)" is able to display good cpu user time and cpu guest
time by subtracting cpu guest time from cpu user time. Update "gtime" in
task_struct accordingly.
Signed-off-by: NLaurent Vivier <Laurent.Vivier@bull.net>
Acked-by: NAvi Kivity <avi@qumranet.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

like for cpustat, introduce the "gtime" (guest time of the task) and
"cgtime" (guest time of the task children) fields for the
tasks. Modify signal_struct and task_struct.

Modify /proc/<pid>/stat to display these new fields.
Signed-off-by: NLaurent Vivier <Laurent.Vivier@bull.net>
Acked-by: NAvi Kivity <avi@qumranet.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

as recent CPUs introduce a third running state, after "user" and
"system", we need a new field, "guest", in cpustat to store the time
used by the CPU to run virtual CPU. Modify /proc/stat to display this
new field.
Signed-off-by: NLaurent Vivier <Laurent.Vivier@bull.net>
Acked-by: NAvi Kivity <avi@qumranet.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

we had an incorrect-terminator bug in sd_alloc_ctl_domain_table()
before, so add a comment that documents it.
Signed-off-by: NMilton Miller <miltonm@bga.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Now that we are calling this at runtime, a more relaxed error path is
suggested.  If an allocation fails, we just register the partial table,
which will show empty directories.
Signed-off-by: NMilton Miller <miltonm@bga.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Unregister and free the sysctl table before destroying domains, then
rebuild and register after creating the new domains.  This prevents the
sysctl table from pointing to freed memory for root to write.
Signed-off-by: NMilton Miller <miltonm@bga.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

init_sched_domain_sysctl was walking cpus 0-n and referencing per_cpu
variables.  If the cpus_possible mask is not contigious this will result
in a crash referencing unallocated data.  If the online mask is not
contigious then we would show offline cpus and miss online ones.
Signed-off-by: NMilton Miller <miltonm@bga.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

kcalloc checks for n * sizeof(element) overflows and it zeros.
Signed-off-by: NMilton Miller <miltonm@bga.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

In general, struct file_operations are const in the kernel, to not have
false cacheline sharing and to catch bugs at compiletime with accidental
writes to them. The new scheduler code introduces a new non-const one;
fix this up.
Signed-off-by: NArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

most multicore CPUs today have shared L2 caches, so tune things so
that the spreading amongst cores is more aggressive.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

reintroduce the 2.6.22 topology.h tunings again - they result in
slightly better balancing.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

allow the immediate migration of cache-cold tasks.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

add new migration statistics when SCHED_DEBUG and SCHEDSTATS
is enabled. Available in /proc/<PID>/sched.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

increase width of debug line - in preparation of more debugging info.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

activate task_hot() only for fair-scheduled tasks (i.e. disable it
for RT tasks).
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

reintroduce a simplified version of cache-hot/cold scheduling
affinity. This improves performance with certain SMP workloads,
such as sysbench.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

speed up context-switches a bit by not clearing p->exec_start.

(as a side-effect, this also makes p->exec_start a universal timestamp
available to cache-hot estimations.)
Signed-off-by: NIngo Molnar <mingo@elte.hu>

do not wakeup-preempt with SCHED_BATCH tasks, their preemption
is batched too, driven by the tick.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Generate uevents when a user is being created/destroyed. These events
can be used to configure cpu share of a new user.
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>

do not normalize kernel threads via SysRq-N: the migration threads,
softlockup threads, etc. might be essential for the system to
function properly. So only zap user tasks.

pointed out by Andi Kleen.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

remove stale comment from sched_group_set_shares().

Function never returns -EINVAL.
Signed-off-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

clean up is_migration_thread() and turn it into an inline function.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Replace a particularly ugly ifdef with an inline and a new macro.
Also split up the function to be easier to read.
Signed-off-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Refactor common code of sleep_on / wait_for_completion

These functions were largely cut'n'pasted. This moves
the common code into single helpers instead.  Advantage
is about 1k less code on x86-64 and 91 lines of code removed.
It adds one function call to the non timeout version of
the functions; i don't expect this to be measurable.
Signed-off-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Replace loops implemented with gotos with real loops.
Replace err = ...; goto x; x: return err; with return ...;

No functional changes.
Signed-off-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

update comment: clarify time-slices and remove obsolete tuning detail.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Prevent wakeup over-scheduling.  Once a task has been preempted by a
task of the same or lower priority, it becomes ineligible for repeated
preemption by same until it has been ticked, or slept.  Instead, the
task is marked for preemption at the next tick.  Tasks of higher
priority still preempt immediately.
Signed-off-by: NMike Galbraith <efault@gmx.de>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Implement feature bit to disable forced preemption. This way
it can be checked whether a workload is overscheduling or not.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The following patch (sched: disable sleeper_fairness on SCHED_BATCH)
seems to break GROUP_SCHED. Although, it may be 'oops'-less due to the
possibility of 'p' being always a valid address.
Signed-off-by: NDmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

cache_nice_tries and flags entry do not appear in proc fs sched_domain
directory, because ctl_table entry is skipped.

This patch fixes the issue.
Signed-off-by: NZou Nan hai <nanhai.zou@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

yield() in wait_task_inactive(), can cause a high priority thread to be
scheduled back in, and there by loop forever while it is waiting for some
lower priority thread which is unfortunately still on the runqueue.

Use schedule_timeout_uninterruptible(1) instead.
Signed-off-by: NGautham R Shenoy <ego@in.ibm.com>
Credit: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Add tunables in sysfs to modify a user's cpu share.

A directory is created in sysfs for each new user in the system.

	/sys/kernel/uids/<uid>/cpu_share

Reading this file returns the cpu shares granted for the user.
Writing into this file modifies the cpu share for the user. Only an
administrator is allowed to modify a user's cpu share.

Ex:
	# cd /sys/kernel/uids/
	# cat 512/cpu_share
	1024
	# echo 2048 > 512/cpu_share
	# cat 512/cpu_share
	2048
	#
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>

disable sleeper fairness for batch tasks - they are about
batch processing after all.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

unit mis-match: wakeup_gran was used against a vruntime
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

export cpu_clock() - the preferred API instead of sched_clock().
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

noticed by Peter Zijlstra:

fix: move the CPU check into ->task_new_fair(), this way we
can call place_entity() and get child ->vruntime right at
initial wakeup time.

(without this there can be large latencies)
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>

noticed by Thomas Gleixner:

cleanup: function prototype cleanups - move into single line
wherever possible.
Signed-off-by: NIngo Molnar <mingo@elte.hu>