Re: [2.6.39-rc2] perf top fails to mmap

[David Ahern]

On 04/06/11 14:48, Tim Blechmann wrote:
>>> David
>>>
>>>> this happens when running perf as the same process as the process and
>>>> when running perf as root.
>>
>> yep, works for me as well:
>>
>> [acme@emilia ~]$ cat vsyscall.c
> 
> after including unistd.h, this compiles and works fine. however i cannot profile 
> any multithreaded program. does this work for you?
> 
> tim
> 

That does fail:
# ps -C rsyslogd -L
  PID   LWP TTY          TIME CMD
  795   795 ?        00:00:00 rsyslogd
  795   797 ?        00:00:00 rsyslogd
  795   798 ?        00:00:00 rsyslogd

# /tmp/build-perf/perf top -p 795
Failed to mmap with 22 (Invalid argument)

strace shows it failing at:
ioctl(4, PERF_EVENT_IOC_SET_OUTPUT, 0x3) = -1 EINVAL (Invalid argument)

Changing to use thread only works:
# /tmp/build-perf/perf top -t 795
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