Messages in this thread | | | Date | Fri, 27 Jan 2023 15:34:49 +0000 | Subject | Re: [PATCH 3/4] perf session: Avoid calling lseek(2) for pipe | From | James Clark <> |
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On 27/01/2023 00:19, Namhyung Kim wrote: > We should not call lseek(2) for pipes as it won't work. And we already > in the proper place to read the data for AUXTRACE. Add the comment like > in the PERF_RECORD_HEADER_TRACING_DATA. > > Signed-off-by: Namhyung Kim <namhyung@kernel.org> > --- > tools/perf/util/session.c | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) > > diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c > index 7c021c6cedb9..fdfe772f2699 100644 > --- a/tools/perf/util/session.c > +++ b/tools/perf/util/session.c > @@ -1699,8 +1699,13 @@ static s64 perf_session__process_user_event(struct perf_session *session, > case PERF_RECORD_AUXTRACE_INFO: > return tool->auxtrace_info(session, event); > case PERF_RECORD_AUXTRACE: > - /* setup for reading amidst mmap */ > - lseek(fd, file_offset + event->header.size, SEEK_SET); > + /* > + * Setup for reading amidst mmap, but only when we > + * are in 'file' mode. The 'pipe' fd is in proper > + * place already. > + */ > + if (!perf_data__is_pipe(session->data)) > + lseek(fd, file_offset + event->header.size, SEEK_SET);
I'm not sure if it means anything, but Arm SPE works both with and without this change, although I did have to skip the build-id inject part:
perf record -o- -e arm_spe// stress -c 1 -t 1 | \ perf report -i- --itrace=i1000
> return tool->auxtrace(session, event); > case PERF_RECORD_AUXTRACE_ERROR: > perf_session__auxtrace_error_inc(session, event);
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