Currently we wake the mmap() consumer once every PAGE_SIZE of data
and/or once event wakeup_events when specified.

For high speed sampling this results in too many wakeups wrt. the
buffer size, hence change this.

We move the default wakeup limit to 1/4-th the buffer size, and
provide for means to manually specify this limit.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

We can have swcounter events that contribute more than a single
count per event, when used with a non-zero period, those can
generate multiple events, which is when we need throttling.

However, swcounter that contribute only a single count per event
can only come as fast as we can run code, hence don't throttle
them.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

This prints a textual context-switching outline of workload
captured via perf sched record.

For example, on a 16 CPU box it outputs:

   N1  O1  .   .   .   S1  .   .   .   B0  .  *I0  C1  .   M1  .    23002.773423 secs
   N1  O1  .  *Q0  .   S1  .   .   .   B0  .   I0  C1  .   M1  .    23002.773423 secs
   N1  O1  .   Q0  .   S1  .   .   .   B0  .  *R1  C1  .   M1  .    23002.773485 secs
   N1  O1  .   Q0  .   S1  .  *S0  .   B0  .   R1  C1  .   M1  .    23002.773478 secs
  *L0  O1  .   Q0  .   S1  .   S0  .   B0  .   R1  C1  .   M1  .    23002.773523 secs
   L0  O1  .  *.   .   S1  .   S0  .   B0  .   R1  C1  .   M1  .    23002.773531 secs
   L0  O1  .   .   .   S1  .   S0  .   B0  .   R1  C1 *T1  M1  .    23002.773547 secs T1 => irqbalance:2089
   L0  O1  .   .   .   S1  .   S0  .  *P0  .   R1  C1  T1  M1  .    23002.773549 secs
  *N1  O1  .   .   .   S1  .   S0  .   P0  .   R1  C1  T1  M1  .    23002.773566 secs
   N1  O1  .   .   .  *J0  .   S0  .   P0  .   R1  C1  T1  M1  .    23002.773571 secs
   N1  O1  .   .   .   J0  .   S0 *B0  P0  .   R1  C1  T1  M1  .    23002.773592 secs
   N1  O1  .   .   .   J0  .  *U0  B0  P0  .   R1  C1  T1  M1  .    23002.773582 secs
   N1  O1  .   .   .  *S1  .   U0  B0  P0  .   R1  C1  T1  M1  .    23002.773604 secs
   N1  O1  .   .   .   S1  .   U0  B0 *.   .   R1  C1  T1  M1  .    23002.773615 secs
   N1  O1  .   .   .   S1  .   U0  B0  .   .  *K0  C1  T1  M1  .    23002.773631 secs
   N1  O1  .  *M0  .   S1  .   U0  B0  .   .   K0  C1  T1  M1  .    23002.773624 secs
   N1  O1  .   M0  .   S1  .   U0 *.   .   .   K0  C1  T1  M1  .    23002.773644 secs
   N1  O1  .   M0  .   S1  .   U0  .   .   .  *R1  C1  T1  M1  .    23002.773662 secs
   N1  O1  .   M0  .   S1  .  *.   .   .   .   R1  C1  T1  M1  .    23002.773648 secs
   N1  O1  .  *.   .   S1  .   .   .   .   .   R1  C1  T1  M1  .    23002.773680 secs
   N1  O1  .   .   .  *L0  .   .   .   .   .   R1  C1  T1  M1  .    23002.773717 secs
  *N0  O1  .   .   .   L0  .   .   .   .   .   R1  C1  T1  M1  .    23002.773709 secs
  *N1  O1  .   .   .   L0  .   .   .   .   .   R1  C1  T1  M1  .    23002.773747 secs

Columns stand for individual CPUs, from CPU0 to CPU15, and the
two-letter shortcuts stand for tasks that are running on a CPU.

'*' denotes the CPU that had the event.

A dot signals an idle CPU.

New tasks are assigned new two-letter shortcuts - when they occur
first they are printed. In the above example 'T1' stood for irqbalance:

      T1 => irqbalance:2089

Cc: Peter 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>

Peter noticed that we have 3 ways of referring to the idle thread:

 [idle]:0
 swapper:0
 swapper-0

Standardize on 'swapper:0'.
Reported-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>

Use 'perf sched latency' to track the current task based on
context-switch events, and flag the cases where there's some
impossible transition: such as a PID being switched out that
was not switched in.

Cc: Peter 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>

Output such lost event and state machine weirdness stats:

   TOTAL:                |  14974.910 ms |    46384 |
  ---------------------------------------------------
   INFO: 8.865% lost events (19132 out of 215819, in 8 chunks)
   INFO: 0.198% state machine bugs (49 out of 24708) (due to lost events?)

And increase buffering to -m 1024 (4 MB) by default. Since we
use output multiplexing that kind of space is needed.

Cc: Peter 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>

This allows more precise 'perf sched latency' output:

 ---------------------------------------------------------------------------------------
  Task                  |  Runtime ms | Switches | Average delay ms | Maximum delay ms |
 ---------------------------------------------------------------------------------------
  ksoftirqd/0-4         |    0.010 ms |        2 | avg:    2.476 ms | max:    2.977 ms |
  perf-12328            |   15.844 ms |       66 | avg:    1.118 ms | max:    9.979 ms |
  bdi-default-235       |    0.009 ms |        1 | avg:    0.998 ms | max:    0.998 ms |
  events/1-8            |    0.020 ms |        2 | avg:    0.998 ms | max:    0.998 ms |
  events/0-7            |    0.018 ms |        2 | avg:    0.992 ms | max:    0.996 ms |
  sleep-12329           |    0.742 ms |        3 | avg:    0.906 ms | max:    2.289 ms |
  sshd-12122            |    0.163 ms |        2 | avg:    0.283 ms | max:    0.562 ms |
  loop-getpid-lon-12322 | 1023.636 ms |       69 | avg:    0.208 ms | max:    5.996 ms |
  loop-getpid-lon-12321 | 1038.638 ms |        5 | avg:    0.073 ms | max:    0.171 ms |
  migration/1-5         |    0.000 ms |        1 | avg:    0.006 ms | max:    0.006 ms |
 ---------------------------------------------------------------------------------------
  TOTAL:                | 2079.078 ms |      153 |
 -------------------------------------------------

Also, streamline the code a bit more, add asserts for various state
machine failures (they should be debugged if they occur) and fix
a few odd ends.

Cc: Peter 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>

Often it's useful to know the PID of the task as well - print it
out too.

( While at it, reformat the output to be a bit more
  paste-into-commit-logs friendly. )

Cc: Peter 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>

Before:

  -----------------------------------------------------------------------------------
   Task              |  Runtime ms | Switches | Average delay ms | Maximum delay ms |
  -----------------------------------------------------------------------------------
   perf              |4853313.251 ms |       10 | avg:    0.046 ms | max:    0.337 ms |
   flush-8:0         |2426659.202 ms |        5 | avg:    0.015 ms | max:    0.016 ms |
   sleep             |485331.966 ms |        1 | avg:    0.012 ms | max:    0.012 ms |
   ksoftirqd/1       |485331.320 ms |        1 | avg:    0.005 ms | max:    0.005 ms |
  -----------------------------------------------------------------------------------
   TOTAL:            |8250635.739 ms |       17 |
  ---------------------------------------------

After:

  -----------------------------------------------------------------------------------
   Task              |  Runtime ms | Switches | Average delay ms | Maximum delay ms |
  -----------------------------------------------------------------------------------
   perf              |    0.206 ms |       10 | avg:    0.046 ms | max:    0.337 ms |
   flush-8:0         |    2.680 ms |        5 | avg:    0.015 ms | max:    0.016 ms |
   sleep             |    0.662 ms |        1 | avg:    0.012 ms | max:    0.012 ms |
   ksoftirqd/1       |    0.015 ms |        1 | avg:    0.005 ms | max:    0.005 ms |
  -----------------------------------------------------------------------------------
   TOTAL:            |    3.563 ms |       17 |
  ---------------------------------------------

Cc: Peter 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>

Finish the -M/--multiplex option implementation:

 - separate it out from group_fd

 - correctly set it via the ioctl and dont mmap counters that
   are multiplexed

 - modify the perf record event loop to deal with buffer-less
   counters.

 - remove the -g option from perf sched record

 - account for unordered events in perf sched latency

 - (add -f to perf sched record to ease measurements)

 - skip idle threads (pid==0) in latency output

The result is better latency output by 'perf sched latency':

 -----------------------------------------------------------------------------------
  Task              |  Runtime ms | Switches | Average delay ms | Maximum delay ms |
 -----------------------------------------------------------------------------------
  ksoftirqd/8       |    0.071 ms |        2 | avg:    0.458 ms | max:    0.913 ms |
  at-spi-registry   |    0.609 ms |       19 | avg:    0.013 ms | max:    0.023 ms |
  perf              |    3.316 ms |       16 | avg:    0.013 ms | max:    0.054 ms |
  Xorg              |    0.392 ms |       19 | avg:    0.011 ms | max:    0.018 ms |
  sleep             |    0.537 ms |        2 | avg:    0.009 ms | max:    0.009 ms |
 -----------------------------------------------------------------------------------
  TOTAL:            |    4.925 ms |       58 |
 ---------------------------------------------

Cc: Peter 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>

Currently it's possible to meet such too high latency results
with 'perf sched latency'.

 -----------------------------------------------------------------------------------
 Task              |  Runtime ms | Switches | Average delay ms | Maximum delay ms |
 -----------------------------------------------------------------------------------
 xfce4-panel       |    0.222 ms |        2 | avg: 4718.345 ms | max: 9436.493 ms |
 scsi_eh_3         |    3.962 ms |       36 | avg:   55.957 ms | max: 1977.829 ms |

The origin is on traces that are sometimes badly serialized across cpus.
For example the raw traces that raised such results for xfce4-panel:

(1)          [init]-0     [000]  1494.663899990: sched_switch: task swapper:0 [140] (R) ==> xfce4-panel:4569 [120]
(2)     xfce4-panel-4569  [000]  1494.663928373: sched_switch: task xfce4-panel:4569 [120] (S) ==> swapper:0 [140]
(3)            Xorg-4276  [001]  1494.663860125: sched_wakeup: task xfce4-panel:4569 [120] success=1 [000]
(4)            Xorg-4276  [001]  1504.098252756: sched_wakeup: task xfce4-panel:4569 [120] success=1 [000]
(5)            perf-5219  [000]  1504.100353302: sched_switch: task perf:5219 [120] (S) ==> xfce4-panel:4569 [120]

The traces are processed in the order they arrive. Then in (2),
xfce4-panel sleeps, it is first waken up in (3) and eventually
scheduled in (5).

The latency reported is then 1504 - 1495 = 9 secs, as reported by perf
sched. But this is wrong, we are confident in the fact the traces are
nicely serialized while we should actually more trust the timestamps.

If we reorder by timestamps we get:

(1)            Xorg-4276  [001]  1494.663860125: sched_wakeup: task xfce4-panel:4569 [120] success=1 [000]
(2)          [init]-0     [000]  1494.663899990: sched_switch: task swapper:0 [140] (R) ==> xfce4-panel:4569 [120]
(3)     xfce4-panel-4569  [000]  1494.663928373: sched_switch: task xfce4-panel:4569 [120] (S) ==> swapper:0 [140]
(4)            Xorg-4276  [001]  1504.098252756: sched_wakeup: task xfce4-panel:4569 [120] success=1 [000]
(5)            perf-5219  [000]  1504.100353302: sched_switch: task perf:5219 [120] (S) ==> xfce4-panel:4569 [120]

Now the trace make more sense, xfce4-panel is sleeping. Then it is
woken up in (1), scheduled in (2)
It goes to sleep in (3), woken up in (4) and scheduled in (5).

Now, latency captured between (1) and (2) is of 39 us.
And between (4) and (5) it is 2.1 ms.

Such pattern of bad serializing is the origin of the high latencies
reported by perf sched.

Basically, we need to check whether wake up time is higher than
schedule out time. If it's not the case, we need to tag the current
work atom as invalid.

Beside that, we may need to work later on a better ordering of the
traces given by the kernel.

After this patch:

xfce4-session     |    0.221 ms |        1 | avg:    0.538 ms | max:    0.538 ms |
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Add an option to multiplex counters output in the channel of
the group leader, ie: the first counter opened:

	-M --multiplex

The effect is better serialized samples. This is especially
useful for tracepoint samples that need to be well serialized
for their post-processing.

Also make use of this option in 'perf sched'.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Peter 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>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

This allows more precise tracking of how the scheduler accounts
(and acts upon) a task having spent N nanoseconds of CPU time.

Cc: Peter 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>

Alias 'perf sched trace' to 'perf trace', for workflow completeness.

Add a bit of documentation for perf sched.

Cc: Peter 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>

Before:

  $ perf sched record -f sleep 1
  Error: failed to mmap with 1 (Operation not permitted)

After:

  $ perf sched record -f sleep 1
  [ perf record: Captured and wrote 0.095 MB perf.data (~4161 samples) ]

Note, this is only allowed if perfcounter_paranoid is set to
the most permissive (non-default) value of -1.

Cc: Peter 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>

Implement the 'perf sched record' subcommand that adds a
default list of events, turns on raw sampling and system-wide
tracing and passes off the rest of the command to perf record.

This is more convenient than having to specify the events all
the time.

Before:

 $ perf record -a -R -e sched:sched_switch:r -e sched:sched_stat_wait:r -e sched:sched_stat_sleep:r -e sched:sched_stat_iowait:r -e sched:sched_process_exit:r -e sched:sched_process_fork:r -e sched:sched_wakeup:r -e sched:sched_migrate_task:r -c 1 sleep 1

After:

 $ perf sched record -f sleep 1

Also fix an assumption in the event string parser that assumed
that strings passed in can be modified. (In this case they wont
be as they come from a readonly constant section.)
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Use a sort list for thread atoms insertion as well - instead of
hardcoded for PID.

Cc: Peter 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>

- Rename 'latency' field/variable names to the better 'atom' ones

 - Reduce the number of #include lines and consolidate them

 - Gather file scope variables at the top of the file

 - Remove unused bits

No change in functionality.

Cc: Peter 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>

Separate the option parsing cleanly and add two variants:

 - 'perf sched latency' (can be abbreviated via 'perf sched lat')
 - 'perf sched replay'  (can be abbreviated via 'perf sched rep')

Also add a repeat count option to replay and add a separation
set of options for replay.

Do the sorting setup only in the latency sub-command.

Display separate help screens for 'perf sched' and
'perf sched replay -h' - i.e. further separation of the
sub-commands.

Cc: Peter 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>

Implement multidimensional sorting on perf sched so that
you can sort either by number of switches, latency average,
latency maximum, runtime.

perf sched -l -s avg,max  (this is the default)

-----------------------------------------------------------------------------------
 Task              |  Runtime ms | Switches | Average delay ms | Maximum delay ms |
-----------------------------------------------------------------------------------
 gnome-power-man   |    0.113 ms |        1 | avg: 4998.531 ms | max: 4998.531 ms |
 xfdesktop         |    1.190 ms |        7 | avg:  136.475 ms | max:  940.933 ms |
 xfce-mcs-manage   |    2.194 ms |       22 | avg:   38.534 ms | max:  735.174 ms |
 notification-da   |    2.749 ms |       31 | avg:   27.436 ms | max:  731.791 ms |
 xfce4-session     |    3.343 ms |       28 | avg:   26.796 ms | max:  734.891 ms |
 xfwm4             |    3.159 ms |       22 | avg:   12.406 ms | max:  241.333 ms |
 xchat             |   42.789 ms |      214 | avg:   11.886 ms | max:  100.349 ms |
 xfce4-terminal    |    5.386 ms |       22 | avg:   11.414 ms | max:  241.611 ms |
 firefox           |  151.992 ms |      123 | avg:    9.543 ms | max:  153.717 ms |
 xfce4-panel       |   24.324 ms |       47 | avg:    8.189 ms | max:  242.352 ms |
 :5090             |    6.932 ms |      111 | avg:    8.131 ms | max:  102.665 ms |
 events/0          |    0.758 ms |       12 | avg:    1.964 ms | max:   21.879 ms |
 Xorg              |  280.558 ms |      340 | avg:    1.864 ms | max:   99.526 ms |
 geany             |   63.391 ms |      295 | avg:    1.099 ms | max:    9.334 ms |
 reiserfs/0        |    0.039 ms |        2 | avg:    0.854 ms | max:    1.487 ms |
 kondemand/0       |    8.251 ms |      245 | avg:    0.691 ms | max:   34.372 ms |
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Peter 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>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

We are dividing a time in ns by 1e9. This is a nsec to sec
conversion. What we want is msecs. Fix it by dividing by 1e6.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Peter 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>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Add a field in the thread atom list that keeps track of the
total and max latencies and also the total runtime. This makes
a faster output and also prepares for sorting.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Peter 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>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Currently in perf sched, we are measuring the scheduler wakeup
latencies.

Now we also want measure the time a task wait to be scheduled
after it gets preempted.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Peter 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>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

To measures the latencies, we capture the sched atoms data into
a specific structure named struct lat_snapshot.

As this structure can be used for other purposes of scheduler
profiling and mirrors what happens in a thread work atom, lets
rename it to struct work_atom and propagate this renaming in
other functions and structures names to keep it coherent.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Peter 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>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

After:

-----------------------------------------------------------------------------------
 Task              |  Runtime ms | Switches | Average delay ms | Maximum delay ms |
-----------------------------------------------------------------------------------
 make              |    0.678 ms |       13 | avg:    0.018 ms | max:    0.050 ms |
 gcc               |    0.014 ms |        2 | avg:    0.320 ms | max:    0.627 ms |
 gcc               |    0.000 ms |        2 | avg:    0.185 ms | max:    0.369 ms |
...
-----------------------------------------------------------------------------------
 TOTAL:            |   21.316 ms |       63 |
---------------------------------------------

Cc: Peter 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>

Extend the latency tracking structure with scheduling atom
runtime info - and sum it up during per task display.

(Also clean up a few details.)

Cc: Peter 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>

After:

-----------------------------------------------------------------------------------
 Task              |  runtime ms | switches | average delay ms | maximum delay ms |
-----------------------------------------------------------------------------------
 migration/0       |    0.000 ms |        1 | avg:    0.047 ms | max:    0.047 ms |
 ksoftirqd/0       |    0.000 ms |        1 | avg:    0.039 ms | max:    0.039 ms |
 migration/1       |    0.000 ms |        3 | avg:    0.013 ms | max:    0.016 ms |
 migration/3       |    0.000 ms |        2 | avg:    0.003 ms | max:    0.004 ms |
 migration/4       |    0.000 ms |        1 | avg:    0.022 ms | max:    0.022 ms |
 distccd           |    0.000 ms |        1 | avg:    0.004 ms | max:    0.004 ms |
 distccd           |    0.000 ms |        1 | avg:    0.014 ms | max:    0.014 ms |
 distccd           |    0.000 ms |        2 | avg:    0.000 ms | max:    0.000 ms |
 distccd           |    0.000 ms |        2 | avg:    0.012 ms | max:    0.019 ms |
 distccd           |    0.000 ms |        1 | avg:    0.002 ms | max:    0.002 ms |
 as                |    0.000 ms |        2 | avg:    0.019 ms | max:    0.019 ms |
 as                |    0.000 ms |        3 | avg:    0.015 ms | max:    0.017 ms |
 as                |    0.000 ms |        1 | avg:    0.009 ms | max:    0.009 ms |
 perf              |    0.000 ms |        1 | avg:    0.001 ms | max:    0.001 ms |
 gcc               |    0.000 ms |        1 | avg:    0.021 ms | max:    0.021 ms |
 run-mozilla.sh    |    0.000 ms |        2 | avg:    0.010 ms | max:    0.017 ms |
 mozilla-plugin-   |    0.000 ms |        1 | avg:    0.006 ms | max:    0.006 ms |
 gcc               |    0.000 ms |        2 | avg:    0.013 ms | max:    0.013 ms |
-----------------------------------------------------------------------------------

(The runtime ms column is not filled in yet.)

Cc: Peter 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>

- Separate the latency and the replay commands more cleanly

 - Use consistent naming

 - Display help page on 'perf sched' outlining comments,
   instead of aborting

Cc: Peter 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>

Add the -l --latency option that reports statistics about the
scheduler latencies.

For now, the latencies are measured in the following sequence
scope:

- task A is sleeping (D or S state)
- task B wakes up A
         ^
         |
         |

   latency timeframe

         |
         |
         v
- task A is scheduled in

Start by recording every scheduler events:

	perf record -e sched:*

and then fetch the results:

	perf sched -l

 Tasks                     count          total              avg            max

migration/0                  2             39849            19924           28826
ksoftirqd/0                  7            756383           108054          373014
migration/1                  5             45391             9078           10452
ksoftirqd/1                  2            399055           199527          359130
events/0                     8           4780110           597513         4500250
events/1                     9           6353057           705895         2986012
kblockd/0                   42          37805097           900121         5077684

The snapshot are in nanoseconds.

- Count: number of snapshots taken for the given task
- Total: total latencies in nanosec
- Avg  : average of latency between wake up and sched in
- Max  : max snapshot latency
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Peter 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>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Create a sched event structure of handlers in which various
sched events reader can plug their own callbacks.

This makes easier the addition of new perf sched sub commands.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Peter 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>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

perf sched raises the following error when it meets a sched
switch event:

perf: builtin-sched.c:286: register_pid: Assertion `!(pid >= 65536)' failed.
Abandon

Currently in x86-64, the sched switch events have a hole in the
middle of the structure:

	u16 common_type;
	u8 common_flags;
	u8 common_preempt_count;
	u32 common_pid;
	u32 common_tgid;

	char prev_comm[16];
	u32 prev_pid;
	u32 prev_prio;
			<--- there
	u64 prev_state;
	char next_comm[16];
	u32 next_pid;
	u32 next_prio;

Gcc inserts a 4 bytes hole there for prev_state to be u64
aligned. And the events are exported to userspace with this
hole.

But in userspace, from perf sched, we fetch it using a
structure that has a new field in the beginning: u32 size. This
is because our trace is exported with its size as a field. But
now that we have this new field, the hole in the middle
disappears because it makes prev_state becoming well aligned.

And since we are using a pointer to the raw trace using this
struct, instead of reading prev_state, we are reading the hole.

We could fix it by keeping the size seperate from the struct
but actually there a lot of other potential problems: some
fields may be saved as long in a 64 bits system and later read
as long in a 32 bits system. Also this direct cast doesn't care
about the endianness differences between the host traced
machine and the machine in which we do the post processing.

So instead of using such dangerous direct casts, fetch the
values using the trace parsing API that already takes care of
all these problems.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Peter 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>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Currently, when one wants to activate every tracepoint
counters of a subsystem from perf record, the current sequence
is needed:

  perf record -e subsys:ev1 -e subsys:ev2 -e subsys:ev3

This may annoy the most patient of us.

Now we can just do:

  perf record -e subsys:*
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Peter 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>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Various small cleanups - removal of debug printks and dead
functions, etc.

Cc: Peter 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>

Integrate the schedbench.c bits with the raw trace events
that we get from the perf machinery, and activate the
workload replayer/simulator.

Example of a captured 'make -j' workload:

$ perf sched

  run measurement overhead: 90 nsecs
  sleep measurement overhead: 2724743 nsecs
  the run test took 1000081 nsecs
  the sleep test took 2981111 nsecs
  version = 0.5
  ...
  nr_run_events:        70
  nr_sleep_events:      66
  nr_wakeup_events:     9
  target-less wakeups:  71
  multi-target wakeups: 47
  run events optimized: 139
  task      0 (                perf:      6607), nr_events: 2
  task      1 (                perf:      6608), nr_events: 6
  task      2 (                    :         0), nr_events: 1
  task      3 (                make:      6609), nr_events: 5
  task      4 (                  sh:      6610), nr_events: 4
  task      5 (                make:      6611), nr_events: 6
  task      6 (                  sh:      6612), nr_events: 4
  task      7 (                make:      6613), nr_events: 5
  task      8 (        migration/11:        25), nr_events: 1
  task      9 (        migration/13:        29), nr_events: 1
  task     10 (        migration/15:        33), nr_events: 1
  task     11 (         migration/9:        21), nr_events: 1
  task     12 (                  sh:      6614), nr_events: 4
  task     13 (                make:      6615), nr_events: 5
  task     14 (                  sh:      6616), nr_events: 4
  task     15 (                make:      6617), nr_events: 7
  task     16 (         migration/3:         9), nr_events: 1
  task     17 (         migration/5:        13), nr_events: 1
  task     18 (         migration/7:        17), nr_events: 1
  task     19 (         migration/1:         5), nr_events: 1
  task     20 (                  sh:      6618), nr_events: 4
  task     21 (                make:      6619), nr_events: 5
  task     22 (                  sh:      6620), nr_events: 4
  task     23 (                make:      6621), nr_events: 10
  task     24 (                  sh:      6623), nr_events: 3
  task     25 (                 gcc:      6624), nr_events: 4
  task     26 (                 gcc:      6625), nr_events: 4
  task     27 (                 gcc:      6626), nr_events: 5
  task     28 (            collect2:      6627), nr_events: 5
  task     29 (                  sh:      6622), nr_events: 1
  task     30 (                make:      6628), nr_events: 7
  task     31 (                  sh:      6630), nr_events: 4
  task     32 (                 gcc:      6631), nr_events: 4
  task     33 (                  sh:      6629), nr_events: 1
  task     34 (                 gcc:      6632), nr_events: 4
  task     35 (                 gcc:      6633), nr_events: 4
  task     36 (            collect2:      6634), nr_events: 4
  task     37 (                make:      6635), nr_events: 8
  task     38 (                  sh:      6637), nr_events: 4
  task     39 (                  sh:      6636), nr_events: 1
  task     40 (                 gcc:      6638), nr_events: 4
  task     41 (                 gcc:      6639), nr_events: 4
  task     42 (                 gcc:      6640), nr_events: 4
  task     43 (            collect2:      6641), nr_events: 4
  task     44 (                make:      6642), nr_events: 6
  task     45 (                  sh:      6643), nr_events: 5
  task     46 (                  sh:      6644), nr_events: 3
  task     47 (                  sh:      6645), nr_events: 4
  task     48 (                make:      6646), nr_events: 6
  task     49 (                  sh:      6647), nr_events: 3
  task     50 (                make:      6648), nr_events: 5
  task     51 (                  sh:      6649), nr_events: 5
  task     52 (                  sh:      6650), nr_events: 6
  task     53 (                make:      6651), nr_events: 4
  task     54 (                make:      6652), nr_events: 5
  task     55 (                make:      6653), nr_events: 4
  task     56 (                make:      6654), nr_events: 4
  task     57 (                make:      6655), nr_events: 5
  task     58 (                  sh:      6656), nr_events: 4
  task     59 (                 gcc:      6657), nr_events: 9
  task     60 (         ksoftirqd/3:        10), nr_events: 1
  task     61 (                 gcc:      6658), nr_events: 4
  task     62 (                make:      6659), nr_events: 5
  task     63 (                  sh:      6660), nr_events: 3
  task     64 (                 gcc:      6661), nr_events: 5
  task     65 (            collect2:      6662), nr_events: 4
  ------------------------------------------------------------
  #1  : 256.745, ravg: 256.74, cpu: 0.00 / 0.00
  #2  : 439.372, ravg: 275.01, cpu: 0.00 / 0.00
  #3  : 411.971, ravg: 288.70, cpu: 0.00 / 0.00
  #4  : 385.500, ravg: 298.38, cpu: 0.00 / 0.00
  #5  : 366.526, ravg: 305.20, cpu: 0.00 / 0.00
  #6  : 381.281, ravg: 312.81, cpu: 0.00 / 0.00
  #7  : 410.756, ravg: 322.60, cpu: 0.00 / 0.00
  #8  : 368.009, ravg: 327.14, cpu: 0.00 / 0.00
  #9  : 408.098, ravg: 335.24, cpu: 0.00 / 0.00
  #10 : 368.582, ravg: 338.57, cpu: 0.00 / 0.00

I.e. we successfully analyzed the trace, replayed it
via real threads and measured the replayed workload's
scheduling properties.

This is how it looked like in 'top' output:

   PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
  7164 mingo     20   0 1434m 8080  888 R 57.0  0.1   0:02.04 :perf
  7165 mingo     20   0 1434m 8080  888 R 41.8  0.1   0:01.52 :perf
  7228 mingo     20   0 1434m 8080  888 R 39.8  0.1   0:01.44 :gcc
  7225 mingo     20   0 1434m 8080  888 R 33.8  0.1   0:01.26 :gcc
  7202 mingo     20   0 1434m 8080  888 R 31.2  0.1   0:01.16 :sh
  7222 mingo     20   0 1434m 8080  888 R 25.2  0.1   0:00.96 :sh
  7211 mingo     20   0 1434m 8080  888 R 21.9  0.1   0:00.82 :sh
  7213 mingo     20   0 1434m 8080  888 D 19.2  0.1   0:00.74 :sh
  7194 mingo     20   0 1434m 8080  888 D 18.6  0.1   0:00.72 :make

There's still various kinks in it - more patches to come.

Cc: Peter 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>

Import the schedbench.c tool that i wrote some time ago to
simulate scheduler behavior but never finished. It's a good
basis for perf sched nevertheless.

Most of its guts are not hooked up to the perf event loop
yet - that will be done in the patches to come.

Cc: Peter 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>

This turn-key tool allows scheduler measurements to be
conducted and the results be displayed numerically.

First baby step towards that goal: clone the new command off of
perf trace.

Fix a few other details along the way:

 - add (minimal) perf trace documentation

 - reorder a few places

 - list perf trace in the mainporcelain list as well
   as it's a very useful utility.

Cc: Peter 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>

* git://git.linux-nfs.org/projects/trondmy/nfs-2.6: (87 commits)
  NFSv4: Disallow 'mount -t nfs4 -overs=2' and 'mount -t nfs4 -overs=3'
  NFS: Allow the "nfs" file system type to support NFSv4
  NFS: Move details of nfs4_get_sb() to a helper
  NFS: Refactor NFSv4 text-based mount option validation
  NFS: Mount option parser should detect missing "port="
  NFS: out of date comment regarding O_EXCL above nfs3_proc_create()
  NFS: Handle a zero-length auth flavor list
  SUNRPC: Ensure that sunrpc gets initialised before nfs, lockd, etc...
  nfs: fix compile error in rpc_pipefs.h
  nfs: Remove reference to generic_osync_inode from a comment
  SUNRPC: cache must take a reference to the cache detail's module on open()
  NFS: Use the DNS resolver in the mount code.
  NFS: Add a dns resolver for use with NFSv4 referrals and migration
  SUNRPC: Fix a typo in cache_pipefs_files
  nfs: nfs4xdr: optimize low level decoding
  nfs: nfs4xdr: get rid of READ_BUF
  nfs: nfs4xdr: simplify decode_exchange_id by reusing decode_opaque_inline
  nfs: nfs4xdr: get rid of COPYMEM
  nfs: nfs4xdr: introduce decode_sessionid helper
  nfs: nfs4xdr: introduce decode_verifier helper
  ...

* 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jgarzik/libata-dev: (25 commits)
  pata_rz1000: use printk_once
  ahci: kill @force_restart and refine CLO for ahci_kick_engine()
  pata_cs5535: add pci id for AMD based CS5535 controllers
  ahci: Add AMD SB900 SATA/IDE controller device IDs
  drivers/ata: use resource_size
  sata_fsl: Defer non-ncq commands when ncq commands active
  libata: add SATA PMP revision information for spec 1.2
  libata: fix off-by-one error in ata_tf_read_block()
  ahci: Gigabyte GA-MA69VM-S2 can't do 64bit DMA
  ahci: make ahci_asus_m2a_vm_32bit_only() quirk more generic
  dmi: extend dmi_get_year() to dmi_get_date()
  dmi: fix date handling in dmi_get_year()
  libata: unbreak TPM filtering by reorganizing ata_scsi_pass_thru()
  sata_sis: convert to slave_link
  sata_sil24: always set protocol override for non-ATAPI data commands
  libata: Export AHCI capabilities
  libata: Delegate nonrot flag setting to SCSI
  [libata] Add pata_rdc driver for RDC ATA devices
  drivers/ata: Remove unnecessary semicolons
  libata: remove spindown skipping and warning
  ...

Merge branch 'tracing-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'tracing-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (105 commits)
  ring-buffer: only enable ring_buffer_swap_cpu when needed
  ring-buffer: check for swapped buffers in start of committing
  tracing: report error in trace if we fail to swap latency buffer
  tracing: add trace_array_printk for internal tracers to use
  tracing: pass around ring buffer instead of tracer
  tracing: make tracing_reset safe for external use
  tracing: use timestamp to determine start of latency traces
  tracing: Remove mentioning of legacy latency_trace file from documentation
  tracing/filters: Defer pred allocation, fix memory leak
  tracing: remove users of tracing_reset
  tracing: disable buffers and synchronize_sched before resetting
  tracing: disable update max tracer while reading trace
  tracing: print out start and stop in latency traces
  ring-buffer: disable all cpu buffers when one finds a problem
  ring-buffer: do not count discarded events
  ring-buffer: remove ring_buffer_event_discard
  ring-buffer: fix ring_buffer_read crossing pages
  ring-buffer: remove unnecessary cpu_relax
  ring-buffer: do not swap buffers during a commit
  ring-buffer: do not reset while in a commit
  ...

Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (64 commits)
  sched: Fix sched::sched_stat_wait tracepoint field
  sched: Disable NEW_FAIR_SLEEPERS for now
  sched: Keep kthreads at default priority
  sched: Re-tune the scheduler latency defaults to decrease worst-case latencies
  sched: Turn off child_runs_first
  sched: Ensure that a child can't gain time over it's parent after fork()
  sched: enable SD_WAKE_IDLE
  sched: Deal with low-load in wake_affine()
  sched: Remove short cut from select_task_rq_fair()
  sched: Turn on SD_BALANCE_NEWIDLE
  sched: Clean up topology.h
  sched: Fix dynamic power-balancing crash
  sched: Remove reciprocal for cpu_power
  sched: Try to deal with low capacity, fix update_sd_power_savings_stats()
  sched: Try to deal with low capacity
  sched: Scale down cpu_power due to RT tasks
  sched: Implement dynamic cpu_power
  sched: Add smt_gain
  sched: Update the cpu_power sum during load-balance
  sched: Add SD_PREFER_SIBLING
  ...