Messages in this thread | | | Date | Fri, 22 Apr 2011 10:37:36 -0600 | From | David Ahern <> | Subject | Re: [2.6.39-rc2] perf top fails to mmap - bisected to 70db7533 |
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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.
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