Commit-ID: 6d13491e2d4944180c9b4fb6ddca4e34b1537836 Gitweb: http://git.kernel.org/tip/6d13491e2d4944180c9b4fb6ddca4e34b1537836 Author: David Carrillo-Cisneros <davi...@google.com> AuthorDate: Mon, 10 Apr 2017 13:14:28 -0700 Committer: Arnaldo Carvalho de Melo <a...@redhat.com> CommitDate: Tue, 11 Apr 2017 15:23:41 -0300
perf tools: Describe pipe mode in perf.data-file-fomat.txt Add a minimal description of pipe's data format. Signed-off-by: David Carrillo-Cisneros <davi...@google.com> Acked-by: Jiri Olsa <jo...@kernel.org> Cc: Alexander Shishkin <alexander.shish...@linux.intel.com> Cc: Andi Kleen <a...@linux.intel.com> Cc: He Kuang <heku...@huawei.com> Cc: Masami Hiramatsu <mhira...@kernel.org> Cc: Paul Turner <p...@google.com> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Simon Que <s...@chromium.org> Cc: Stephane Eranian <eran...@google.com> Cc: Wang Nan <wangn...@huawei.com> Link: http://lkml.kernel.org/r/20170410201432.24807-4-davi...@google.com Signed-off-by: Arnaldo Carvalho de Melo <a...@redhat.com> --- tools/perf/Documentation/perf.data-file-format.txt | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-) diff --git a/tools/perf/Documentation/perf.data-file-format.txt b/tools/perf/Documentation/perf.data-file-format.txt index b664b18..fa2a913 100644 --- a/tools/perf/Documentation/perf.data-file-format.txt +++ b/tools/perf/Documentation/perf.data-file-format.txt @@ -11,8 +11,8 @@ All fields are in native-endian of the machine that generated the perf.data. When perf is writing to a pipe it uses a special version of the file format that does not rely on seeking to adjust data offsets. This -format is not described here. The pipe version can be converted to -normal perf.data with perf inject. +format is described in "Pipe-mode data" section. The pipe data version can be +augmented with additional events using perf inject. The file starts with a perf_header: @@ -411,6 +411,21 @@ An array bound by the perf_file_section size. ids points to a array of uint64_t defining the ids for event attr attr. +Pipe-mode data + +Pipe-mode avoid seeks in the file by removing the perf_file_section and flags +from the struct perf_header. The trimmed header is: + +struct perf_pipe_file_header { + u64 magic; + u64 size; +}; + +The information about attrs, data, and event_types is instead in the +synthesized events PERF_RECORD_ATTR, PERF_RECORD_HEADER_TRACING_DATA and +PERF_RECORD_HEADER_EVENT_TYPE that are generated by perf record in pipe-mode. + + References: include/uapi/linux/perf_event.h
