From: David Ahern <dsahern@gmail.com>
To: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: Tim Blechmann <tim@klingt.org>, linux-kernel@vger.kernel.org
Subject: Re: [2.6.39-rc2] perf top fails to mmap - bisected to 70db7533
Date: Fri, 22 Apr 2011 10:37:36 -0600 [thread overview]
Message-ID: <4DB1AED0.60600@gmail.com> (raw)
In-Reply-To: <4D9CECF5.3090309@gmail.com>
I know you've been busy with other stuff the past few weeks, but have
you had a chance to look into this? Basically, perf in 2.6.39 is broken
when trying to profile a process (-p argument to record or top).
David
> On 04/06/11 16:15, David Ahern wrote:
>>
>>
>> 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
>
> git bisect points to:
>
> 70db7533caef02350ec8d6852e589491bca3a951 is the first bad commit
> commit 70db7533caef02350ec8d6852e589491bca3a951
> Author: Arnaldo Carvalho de Melo <acme@redhat.com>
> Date: Wed Jan 12 22:39:13 2011 -0200
>
> perf evlist: Move the mmap array from perf_evsel
>
> Adopting the new model used in 'perf record', where we don't have a map
> per thread per cpu, instead we have an mmap per cpu, established on the
> first fd for that cpu and ask the kernel using the
> PERF_EVENT_IOC_SET_OUTPUT ioctl to send events for the other fds on that
> cpu for the one with the mmap.
>
> The methods moved from perf_evsel to perf_evlist, but for easing review
> they were modified in place, in evsel.c, the next patch will move the
> migrated methods to evlist.c.
>
> With this 'perf top' now uses the same mmap model used by 'perf record'
> and the next patches will make 'perf record' use these new routines,
> establishing a common codebase for both tools.
>
> ----------
>
> Coincidentally, perf-record is also broken. git bisect points to:
>
> dd7927f4f8ee75b032ff15aeef4bda49719a443a is the first bad commit
> commit dd7927f4f8ee75b032ff15aeef4bda49719a443a
> Author: Arnaldo Carvalho de Melo <acme@redhat.com>
> Date: Wed Jan 12 14:28:51 2011 -0200
>
> perf record: Use perf_evsel__open
>
> Now its time to factor out the mmap handling bits into the perf_evsel
> class.
next prev parent reply other threads:[~2011-04-22 16:37 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-06 10:51 [2.6.39-rc2] perf top fails to mmap Tim Blechmann
2011-04-06 15:20 ` David Ahern
2011-04-06 17:52 ` Arnaldo Carvalho de Melo
2011-04-06 20:48 ` Tim Blechmann
2011-04-06 22:15 ` David Ahern
2011-04-06 22:45 ` [2.6.39-rc2] perf top fails to mmap - bisected to 70db7533 David Ahern
2011-04-07 0:13 ` Arnaldo Carvalho de Melo
2011-04-22 16:37 ` David Ahern [this message]
2011-04-23 13:45 ` Lin Ming
[not found] ` <BANLkTikWpnnHAfO2n2rN6ExtQyrsVaiqEQ@mail.gmail.com>
2011-04-23 14:51 ` Lin Ming
2011-04-24 11:47 ` Tim Blechmann
2011-04-24 13:45 ` David Ahern
2011-04-24 15:02 ` Lin Ming
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