Re: perf: perf sched lat segfault - bisected

[Stephane Eranian]

Mike,

I found the problem in perf. The tool->mmap2 pointer is NULL for sched tool.
Let me send you a patch to fix this.


On Tue, Oct 8, 2013 at 12:25 PM, Stephane Eranian <eranian@xxxxxxxxxx> wrote:
> Mike,
>
> Ok, I missed the sched record, let me track this down.
> Note that there was a second commit to fix this one
> by Arnaldo. Do you also have it in your kernel?
>
> 51131c4 perf: Fix up MMAP2 buffer space reservation
>
> I will try to reproduce your problem ASAP.
>
>
> On Tue, Oct 8, 2013 at 12:20 PM, Mike Galbraith <bitbucket@xxxxxxxxx> wrote:
>> On Tue, 2013-10-08 at 12:14 +0200, Mike Galbraith wrote:
>>> On Tue, 2013-10-08 at 11:23 +0200, Stephane Eranian wrote:
>>> > On Tue, Oct 8, 2013 at 10:41 AM, Mike Galbraith <bitbucket@xxxxxxxxx> wrote:
>>> > > Box: Q6600
>>> > >
>>> > > Reproducer:
>>> > > perf sched record -- sleep 1
>>> > > perf sched lat (boom)
>>> > >
>>> > I don't understand the test case here.
>>> > If I do this, perf sched lat complains of no trace records
>>> > and no kernel crash. Could you provide the full cmdline?
>>>
>>> Hm.  That was it, just like so.
>>>
>>> marge:/usr/local/src/kernel/linux-3.x.git/tools/perf # ./perf sched record -- sleep 1
>>> [ perf record: Woken up 1 times to write data ]
>>> [ perf record: Captured and wrote 0.763 MB perf.data (~33348 samples) ]
>>> marge:/usr/local/src/kernel/linux-3.x.git/tools/perf # ./perf sched lat
>>> Segmentation fault
>>> marge:/usr/local/src/kernel/linux-3.x.git/tools/perf #
>>
>> commit 72f3bdf7fd1003373b454bf923d3a196bbc36600
>> Author: Mike Galbraith <mgalbraith@xxxxxxx>
>> Date:   Tue Oct 8 12:18:37 2013 +0200
>>
>>     Revert "perf tools: Add attr->mmap2 support"
>>
>>     This reverts commit 5c5e854bc760a2e2c878df3cfcf2afa4febcd511.
>>
>> commit a8af8531d08d3edb37a7d67d1a4dc2e1f2f4da58
>> Author: Mike Galbraith <mgalbraith@xxxxxxx>
>> Date:   Tue Oct 8 12:18:23 2013 +0200
>>
>>     Revert "perf trace: Add mmap2 handler"
>>
>>     This reverts commit 384c671e33a7ddf905f2c60b433b9883f0e5a605.
>>
>> marge:/usr/local/src/kernel/linux-3.x.git/tools/perf # ./perf sched
>> record -- sleep 1
>> [ perf record: Woken up 1 times to write data ]
>> [ perf record: Captured and wrote 0.647 MB perf.data (~28289 samples) ]
>> marge:/usr/local/src/kernel/linux-3.x.git/tools/perf # perf sched lat
>> marge:/usr/local/src/kernel/linux-3.x.git/tools/perf #
>>
>> (emitted this)
>>
>>  ---------------------------------------------------------------------------------------------------------------
>>   Task                  |   Runtime ms  | Switches | Average delay ms | Maximum delay ms | Maximum delay at     |
>>  ---------------------------------------------------------------------------------------------------------------
>>   kworker/3:2:383       |      0.073 ms |        1 | avg:    0.020 ms | max:    0.020 ms | max at: 7197.856052 s
>>   sleep:24717           |      1.163 ms |        3 | avg:    0.011 ms | max:    0.022 ms | max at: 7196.884445 s
>>   kworker/2:1:36        |      0.097 ms |        1 | avg:    0.007 ms | max:    0.007 ms | max at: 7197.796023 s
>>   haveged:3547          |      0.023 ms |        2 | avg:    0.006 ms | max:    0.009 ms | max at: 7197.796345 s
>>   rcu_sched:9           |      0.126 ms |       14 | avg:    0.006 ms | max:    0.021 ms | max at: 7196.897051 s
>>   ntpd:4185             |      0.034 ms |        1 | avg:    0.004 ms | max:    0.004 ms | max at: 7197.746409 s
>>   kded4:4594            |      0.058 ms |        1 | avg:    0.004 ms | max:    0.004 ms | max at: 7197.422130 s
>>   evolution:15686       |      0.065 ms |        1 | avg:    0.004 ms | max:    0.004 ms | max at: 7196.915715 s
>>   pickup:21579          |      0.062 ms |        1 | avg:    0.004 ms | max:    0.004 ms | max at: 7197.329185 s
>>   JS Watchdog:20053     |      0.020 ms |        1 | avg:    0.004 ms | max:    0.004 ms | max at: 7197.623752 s
>>   perf:24716            |      3.330 ms |        1 | avg:    0.004 ms | max:    0.004 ms | max at: 7197.885690 s
>>   plasma-desktop:4685   |      1.632 ms |        2 | avg:    0.004 ms | max:    0.005 ms | max at: 7196.933762 s
>>   master:4307           |      0.104 ms |        2 | avg:    0.004 ms | max:    0.005 ms | max at: 7197.329136 s
>>   Xorg:4331             |      0.485 ms |        4 | avg:    0.003 ms | max:    0.005 ms | max at: 7197.010801 s
>>   ksoftirqd/2:18        |      0.014 ms |        1 | avg:    0.003 ms | max:    0.003 ms | max at: 7196.897039 s
>>   alsa-sink:5282        |      0.000 ms |      200 | avg:    0.003 ms | max:    0.003 ms | max at: 7196.905149 s
>>   migration/3:22        |      0.000 ms |        1 | avg:    0.002 ms | max:    0.002 ms | max at: 7196.884423 s
>>  -----------------------------------------------------------------------------------------
>>   TOTAL:                |      7.285 ms |      237 |
>>  ---------------------------------------------------
>>
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