Re: perf: commit 55b4462 causes perf record to hang

David Ahern
2011-01-10T20:07:41Z

On 01/10/11 13:00, Arnaldo Carvalho de Melo wrote:
> Em Mon, Jan 10, 2011 at 11:47:43AM -0700, David Ahern escreveu:
>> With latest version of perf-core branch, a variant of perf record hangs:
>> # /tmp/build-perf/perf record -v -e cs -fo /tmp/perf.data -- sleep 1
>> [ perf record: Captured and wrote 0.003 MB /tmp/perf.data (~120 samples) ]
>>
>> It sits there forever. Back trace is:
>>
>> (gdb) bt
>> #0 0x0000000000447658 in __perf_session__process_events (session=0xab9500, data_offset=208, data_size=2896, file_size=3104, ops=0x685580) at util/session.c:1006
>> #1 0x00000000004107dd in process_buildids () at builtin-record.c:466
>> #2 0x000000000041084d in atexit_header () at builtin-record.c:477
>
>> git bisect traced the hang to
>>
>> commit 55b44629f599a2305265ae9c77f9d9bcfd6ddc17
>> Author: Thomas Gleixner <tglx@linutronix.de>
>> Date: Tue Nov 30 17:49:46 2010 +0000
>
> Can you try with this patch, not reverting tglx's patch?
>
> diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
> index 6fb4694..313dac2 100644
> --- a/tools/perf/util/session.c
> +++ b/tools/perf/util/session.c
> @@ -1007,7 +1007,7 @@ more:
> if (size == 0)
> size = 8;
>
> - if (head + event->header.size >= mmap_size) {
> + if (head + event->header.size > mmap_size) {
> if (mmaps[map_idx]) {
> munmap(mmaps[map_idx], mmap_size);
> mmaps[map_idx] = NULL;

That does the trick -- perf-record exits fine.

David

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