Messages in this thread Patch in this message | | | Date | Tue, 5 May 2020 00:57:07 +0200 | From | Jiri Olsa <> | Subject | Re: [PATCH] perf session: Try to read pipe data from file |
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On Fri, May 01, 2020 at 01:34:47PM +0200, Jiri Olsa wrote: > From: Jiri Olsa <jolsa@redhat.com> > > Ian came with the idea of having support to read the pipe > data also from file [1]. Currently pipe mode files fails > like: > > $ perf record -o - sleep 1 > /tmp/perf.pipe.data > $ perf report -i /tmp/perf.pipe.data > incompatible file format (rerun with -v to learn more) > > This patch adds the support to do that by trying the pipe > header first, and if its successfully detected, switching > the perf data to pipe mode. > > [1] https://lore.kernel.org/lkml/20200409185744.255881-1-irogers@google.com/ > Original-patch-by: Ian Rogers <irogers@google.com> > Signed-off-by: Jiri Olsa <jolsa@kernel.org>
actualy.. I found another issue while trying this on tracepoints:
# ./perf record -g -e 'raw_syscalls:sys_enter' -o - true > data [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.000 MB - ] # ./perf script -i ./data perf_event__process_tracing_data: tracing data size mismatch0x1034 [0xc]: failed to process type: 66
it's because some of the pipe synthesize code calls lseek, which fails on pipe, but succeeds on normal file (with pipe data)
patch below fixes that for me, but I wonder there are other leftovers like this.. I'll check on post it all together
jirka
--- diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c index 8ca709f938b8..33e299674121 100644 --- a/tools/perf/util/header.c +++ b/tools/perf/util/header.c @@ -3955,13 +3955,8 @@ int perf_event__process_tracing_data(struct perf_session *session, { ssize_t size_read, padding, size = event->tracing_data.size; int fd = perf_data__fd(session->data); - off_t offset = lseek(fd, 0, SEEK_CUR); char buf[BUFSIZ]; - /* setup for reading amidst mmap */ - lseek(fd, offset + sizeof(struct perf_record_header_tracing_data), - SEEK_SET); - size_read = trace_report(fd, &session->tevent, session->repipe); padding = PERF_ALIGN(size_read, sizeof(u64)) - size_read; diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c index c11d89e0ee55..b75df19feaf1 100644 --- a/tools/perf/util/session.c +++ b/tools/perf/util/session.c @@ -1543,7 +1543,8 @@ static s64 perf_session__process_user_event(struct perf_session *session, return 0; case PERF_RECORD_HEADER_TRACING_DATA: /* setup for reading amidst mmap */ - lseek(fd, file_offset, SEEK_SET); + if (!perf_data__is_pipe(session->data)) + lseek(fd, file_offset, SEEK_SET); return tool->tracing_data(session, event); case PERF_RECORD_HEADER_BUILD_ID: return tool->build_id(session, event);
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