After babeltrace commit 5cec03e402aa ("ir: copy variants and sequences
when setting a field path"), 'perf data convert' gets incorrect result
if there's bpf output data. For example:
# perf data convert --to-ctf ./out.ctf
# babeltrace ./out.ctf
[10:44:31.186045346] (+?.?????????) evt: { cpu_id = 0 }, { perf_ip = 0xFFFFFFFF810E7DD1, perf_tid = 23819, perf_pid = 23819, perf_id = 518, raw_len = 3, raw_data = [ [0] = 0xC028E32F, [1] = 0x815D0100, [2] = 0x1000000 ] }
[10:44:31.286101003] (+0.100055657) evt: { cpu_id = 0 }, { perf_ip = 0xFFFFFFFF8105B609, perf_tid = 23819, perf_pid = 23819, perf_id = 518, raw_len = 3, raw_data = [ [0] = 0x35D9F1EB, [1] = 0x15D81, [2] = 0x2 ] }
The expected result of the first sample should be:
raw_data = [ [0] = 0x2FE328C0, [1] = 0x15D81, [2] = 0x1 ] }
however, 'perf data convert' output big endian value to resuling CTF
file.
The reason is a internal change (or a bug?) of babeltrace.
Before this patch, at the first add_bpf_output_values(), byte order of
all integer type is uncertain (is 0, neither 1234 (le) nor 4321 (be)).
It would be fixed by:
perf_evlist__deliver_sample
-> process_sample_event
-> ctf_stream
...
->bt_ctf_trace_add_stream_class
->bt_ctf_field_type_structure_set_byte_order
->bt_ctf_field_type_integer_set_byte_order
during creating the stream.
However, the babeltrace commit mentioned above duplicates types in
sequence to prevent potential conflict in following call stack and link
the newly allocated type into the 'raw_data' sequence:
perf_evlist__deliver_sample
-> process_sample_event
-> ctf_stream
...
-> bt_ctf_trace_add_stream_class
-> bt_ctf_stream_class_resolve_types
...
-> bt_ctf_field_type_sequence_copy
->bt_ctf_field_type_integer_copy
This happens before byte order setting, so only the newly allocated
type is initialized, the byte order of original type perf choose to
create the first raw_data is still uncertain.
Byte order in CTF output is not related to byte order in perf.data.
Setting it to anything other than BT_CTF_BYTE_ORDER_NATIVE solves this
problem (only BT_CTF_BYTE_ORDER_NATIVE needs to be fixed). To reduce
behavior changing, set byte order according to compiling options.
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Jeremie Galarneau <jeremie.galarneau@efficios.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1456479154-136027-10-git-send-email-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
f8dd2d5ff9