There was a bug in the old period code that caused intel_pmu_enable_all()
or native_write_msr_safe() to show up quite high in the profiles.

In staring at that code it made my head hurt, so I rewrote it in a
hopefully simpler fashion. Its now fully symetric between tick and
overflow driven adjustments and uses less data to boot.

The only complication is that it basically wants to do a u128 division.
The code approximates that in a rather simple truncate until it fits
fashion, taking care to balance the terms while truncating.

This version does not generate that sampling artefact.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Cc: <stable@kernel.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

When a task gets scheduled in. We don't touch the cpu bound events
so the priority order becomes:

	cpu pinned, cpu flexible, task pinned, task flexible.

So schedule out cpu flexibles when a new task context gets in
and correctly order the groups to schedule in:

	task pinned, cpu flexible, task flexible.

Cpu pinned groups don't need to be touched at this time.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>

We don't need to schedule in/out pinned events on task tick,
now that pinned and flexible groups can be scheduled separately.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>

Tune the scheduling helpers so that we can choose to schedule either
pinned and/or flexible groups from a context.

And while at it, refactor a bit the naming of these helpers to make
these more consistent and flexible.

There is no (intended) change in scheduling behaviour in this
patch.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>

__perf_event_sched_out doesn't need to be globally available, make
it static.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>

Before scheduling an event group, we first check if a group can go
on. We first check if the group is made of software only events
first, in which case it is enough to know if the group can be
scheduled in.

For that purpose, we iterate through the whole group, which is
wasteful as we could do this check when we add/delete an event to
a group.

So we create a group_flags field in perf event that can host
characteristics from a group of events, starting with a first
PERF_GROUP_SOFTWARE flag that reduces the check on the fast path.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Acked-by: NPeter Zijlstra <peterz@infradead.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>

This is more proper that doing it through a list_for_each_entry()
that breaks after the first entry.

v2: Don't rotate pinned groups as its not needed to time share
them.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Acked-by: NPeter Zijlstra <peterz@infradead.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>

Split-up struct perf_event_context::group_list into pinned_groups
and flexible_groups (non-pinned).

This first appears to be useless as it duplicates various loops around
the group list handlings.

But it scales better in the fast-path in perf_sched_in(). We don't
anymore iterate twice through the entire list to separate pinned and
non-pinned scheduling. Instead we interate through two distinct lists.

The another desired effect is that it makes easier to define distinct
scheduling rules on both.

Changes in v2:
- Respectively rename pinned_grp_list and
  volatile_grp_list into pinned_groups and flexible_groups as per
  Ingo suggestion.
- Various cleanups
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Acked-by: NPeter Zijlstra <peterz@infradead.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>

Liming found a NULL deref when a task has a perf context but no
counters  when it forks.

This can occur in two cases, a race during construction where
the fork hits after installing the context but before the first
counter gets inserted, or more reproducably, a fork after the
last counter is closed (which leaves the context around).
Reported-by: NWang Liming <liming.wang@windriver.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
CC: <stable@kernel.org>
LKML-Reference: <1262185684.7135.222.camel@laptop>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Quoted from Ingo:

| This reminds me - i think we should eliminate CONFIG_EVENT_PROFILE -
| it's an unnecessary Kconfig complication. If both PERF_EVENTS and
| EVENT_TRACING is enabled we should expose generic tracepoints.
|
| Nor is it limited to event 'profiling', so it has become a misnomer as
| well.
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <4B2F1557.2050705@cn.fujitsu.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Since we only ever schedule the local cpu, there is no need to pass the
cpu number to the perf sched hooks.

This micro-optimizes things a bit.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

It seems a couple places such as arch/ia64/kernel/perfmon.c and
drivers/infiniband/core/uverbs_main.c could use anon_inode_getfile()
instead of a private pseudo-fs + alloc_file(), if only there were a way
to get a read-only file.  So provide this by having anon_inode_getfile()
create a read-only file if we pass O_RDONLY in flags.
Signed-off-by: NRoland Dreier <rolandd@cisco.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Acme noticed that his FORK/MMAP numbers were inflated by about
the same factor as his cpu-count.

This led to the discovery of a few more sites that need to
respect the event->cpu filter.
Reported-by: NArnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <20091217121830.215333434@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Also, we want to check against nr_cpu_ids, not num_possible_cpus().
The latter works, but the correct bounds check is < nr_cpu_ids.
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
To: Thomas Gleixner <tglx@linutronix.de>

In order to allow for per-task-per-cpu counters, useful for
scalability when profiling task hierarchies, we allow installing
events with event->cpu != -1 in task contexts.

__perf_event_sched_in() already skips events where ->cpu
mis-matches the current cpu, fix up __perf_install_in_context()
and __perf_event_enable() to also respect this filter.

This does lead to vary hard to interpret enabled/running times
for such counters, but I don't see a simple solution for that.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: fweisbec@gmail.com
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <20091216165904.831451147@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The miss-alignment of bp_addr created a 32bit hole, causing
different structure packings on 32 and 64 bit machines.

Fix that by moving __reserve_2 into that hole.

Further, remove the useless struct and redundant __bp_reserve
muck.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <1260902591.8023.781.camel@laptop>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

It is quite legitimate for CPUs to be numbered sparsely, meaning
that it possible for an online CPU to have a number which is
greater than the total count of possible CPUs.

Currently find_get_context() has a sanity check on the cpu
number where it checks it against num_possible_cpus().  This
test can fail for a legitimate cpu number if the
cpu_possible_mask is sparsely populated.

This fixes the problem by checking the CPU number against
nr_cpumask_bits instead, since that is the appropriate check to
ensure that the cpu number is same to pass to cpu_isset()
subsequently.
Reported-by: NMichael Neuling <mikey@neuling.org>
Signed-off-by: NPaul Mackerras <paulus@samba.org>
Tested-by: NMichael Neuling <mikey@neuling.org>
Acked-by: NPeter Zijlstra <peterz@infradead.org>
Cc: <stable@kernel.org>
LKML-Reference: <20091215084032.GA18661@brick.ozlabs.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Convert locks which cannot be sleeping locks in preempt-rt to
raw_spinlocks.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NPeter Zijlstra <peterz@infradead.org>
Acked-by: NIngo Molnar <mingo@elte.hu>

Signed-off-by: NXiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <4B20BAA6.7010609@cn.fujitsu.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

fix:

 [<c0477471>] ? printk+0x1d/0x24
 [<c01c98f9>] ? perf_prepare_sample+0x269/0x280
 [<c0149231>] warn_slowpath_common+0x71/0xd0
 [<c01c98f9>] ? perf_prepare_sample+0x269/0x280
 [<c01492aa>] warn_slowpath_null+0x1a/0x20
 [<c01c98f9>] perf_prepare_sample+0x269/0x280
 [<c016e9f3>] ? cpu_clock+0x53/0x90
 [<c01cc368>] __perf_event_overflow+0x2a8/0x300
 [<c01ccc3b>] perf_event_overflow+0x1b/0x30
 [<c01ccccf>] perf_swevent_hrtimer+0x7f/0x120

This is because 'data.raw' variable not initialize.
Signed-off-by: NXiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Acked-by: NPeter Zijlstra <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <4B208E93.1010801@cn.fujitsu.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Using atomic64_xchg() instead of atomic64_read() and
atomic64_set().
Signed-off-by: NXiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Reviewed-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <4B1F19DC.90204@cn.fujitsu.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

In current code, children task will allocate memory for
'child->perf_event_ctxp' if the parent is counted, we can
do it only if the parent allowed children inherit it.

It can save memory and reduce overhead.
Signed-off-by: NXiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Reviewed-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <4B1F19A8.5040805@cn.fujitsu.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Clean up the code a bit:

 - define 'perf_cpu_context' variable with 'static'
 - use kzalloc() instead of kmalloc() and memset()
Signed-off-by: NXiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Reviewed-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <4B1F194D.7080306@cn.fujitsu.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Currently, when ptrace needs to modify a breakpoint, like disabling
it, changing its address, type or len, it calls
modify_user_hw_breakpoint(). This latter will perform the heavy and
racy task of unregistering the old breakpoint and registering a new
one.

This is racy as someone else might steal the reserved breakpoint
slot under us, which is undesired as the breakpoint is only
supposed to be modified, sometimes in the middle of a debugging
workflow. We don't want our slot to be stolen in the middle.

So instead of unregistering/registering the breakpoint, just
disable it while we modify its breakpoint fields and re-enable it
after if necessary.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prasad <prasad@linux.vnet.ibm.com>
LKML-Reference: <1260347148-5519-1-git-send-regression-fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

struct perf_event::event callback was called when a breakpoint
triggers. But this is a rather opaque callback, pretty
tied-only to the breakpoint API and not really integrated into perf
as it triggers even when we don't overflow.

We prefer to use overflow_handler() as it fits into the perf events
rules, being called only when we overflow.
Reported-by: NPeter Zijlstra <peterz@infradead.org>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: "K. Prasad" <prasad@linux.vnet.ibm.com>

That is "success", "unknown", "through", "performance", "[re|un]mapping"
, "access", "default", "reasonable", "[con]currently", "temperature"
, "channel", "[un]used", "application", "example","hierarchy", "therefore"
, "[over|under]flow", "contiguous", "threshold", "enough" and others.
Signed-off-by: NAndré Goddard Rosa <andre.goddard@gmail.com>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

In the CONFIG_PERF_USE_VMALLOC case, perf_mmap_data_free() only
schedules the cleanup of the perf_mmap_data struct.  In that
case we have to wait until the work has been done before we free
data.
Signed-off-by: NKristian Høgsberg <krh@bitplanet.net>
Cc: David S. Miller <davem@davemloft.net>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: <stable@kernel.org>
LKML-Reference: <1259697901-1747-1-git-send-email-krh@bitplanet.net>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

In current code in perf_swevent_hrtimer(), data.period is not
initialized, The result is obvious wrong:

 # ./perf record -f -e cpu-clock make
 # ./perf report
 # Samples: 1740
 #
 # Overhead   Command                                   ......
 # ........  ........  ..........................................
 #
   1025422183050275328.00%        sh  libc-2.9.90.so ...
   1025422183050275328.00%      perl  libperl.so     ...
   1025422168240043264.00%      perl  [kernel]       ...
   1025422030011210752.00%      perl  [kernel]       ...
Signed-off-by: NXiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Acked-by: NPeter Zijlstra <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: <stable@kernel.org>
LKML-Reference: <4B14E220.2050107@cn.fujitsu.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

When a pinned group cannot be scheduled it goes into error state.

Normally a group cannot go out of error state without being
explicitly re-enabled or disabled. There was a bug in per-thread
mode, whereby upon termination of the thread, the group would
transition from error to off leading to bogus counts and timing
information returned by read().

Fix it by clearing the error state.
Signed-off-by: NStephane Eranian <eranian@google.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: perfmon2-devel@lists.sourceforge.net
LKML-Reference: <4b0eb9ce.0508d00a.573b.ffffeab6@mx.google.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

bp_perf_event_destroy() is unused in its off-case version, let's
remove it to fix the following warning reported by Stephen
Rothwell in linux-next:

  kernel/perf_event.c:4306: warning: 'bp_perf_event_destroy' defined but not used
Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <1259180453-5813-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

In fail case, perf_event_create_kernel_counter() returns NULL
instead of an error, which doesn't help us to inform the user
about the origin of the problem from the outer most callers.
Often we can just return -EINVAL, which doesn't help anyone when
it's eventually about a memory allocation failure.

Then, this patch makes perf_event_create_kernel_counter() always
return a detailed error code.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Prasad <prasad@linux.vnet.ibm.com>
LKML-Reference: <1259210142-5714-2-git-send-regression-fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Commit 4ed7c92d
(perf_events: Undo some recursion damage) has introduced a bad
reference counting of the recursion context. putting the context
behaves like getting it, dropping every software/trace events
after the first one in a context.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1259091502-5171-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

When using an event group, the value and id for non leaders events
were wrong due to invalid offset into the outgoing buffer.
Signed-off-by: NStephane Eranian <eranian@google.com>
Acked-by: NPeter Zijlstra <peterz@infradead.org>
Cc: paulus@samba.org
Cc: perfmon2-devel@lists.sourceforge.net
LKML-Reference: <4b0b71e1.0508d00a.075e.ffff84a3@mx.google.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Add the remaining necessary bits to support breakpoints created
through perf syscall.

We don't use the software counter interface as:

- We don't need to check against recursion, this is already done
  in hardware breakpoints arch level.

- We already know the perf event we are dealing with when the
  event is to be committed.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Prasad <prasad@linux.vnet.ibm.com>
LKML-Reference: <1258987355-8751-3-git-send-email-fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

It is quite possible to call update_event_times() on a context
that isn't actually running and thereby confuse the thing.

perf stat was reporting !100% scale values for software counters
(2e2af50b perf_events: Disable events when we detach them,
solved the worst of that, but there was still some left).

The thing that happens is that because we are not self-reaping
(we have a caring parent) there is a time between the last
schedule (out) and having do_exit() called which will detach the
events.

This period would be accounted as enabled,!running because the
event->state==INACTIVE, even though !event->ctx->is_active.

Similar issues could have been observed by calling read() on a
event while the attached task was not scheduled in.

Solve this by teaching update_event_times() about
ctx->is_active.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1258984836.4531.480.camel@laptop>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Make perf_swevent_get_recursion_context return a context number
and disable preemption.

This could be used to remove the IRQ disable from the trace bit
and index the per-cpu buffer with.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <20091123103819.993226816@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Move the update_event_times() call in __perf_event_exit_task()
into list_del_event() because that holds the proper lock
(ctx->lock) and seems a more natural place to do the last time
update.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20091123103819.842455480@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

It appeared we did call update_event_times() on exit, but we
failed to update the context time, which renders the former
moot.

Locking is a bit iffy, we call update_event_times under
ctx->mutex instead of ctx->lock - the next patch fixes this.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20091123103819.764207355@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

If we leave the event in STATE_INACTIVE, any read of the event
after the detach will increase the running count but not the
enabled count and cause funny scaling artefacts.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20091123103819.689055515@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20091123103819.613427378@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>