Messages in this thread | | | Date | Mon, 28 Jun 2021 20:08:02 +0800 | From | Leo Yan <> | Subject | Re: [PATCH v7 2/2] perf cs-etm: Split --dump-raw-trace by AUX records |
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On Mon, Jun 28, 2021 at 11:38:34AM +0100, James Clark wrote:
[...]
> >> static int cs_etm__process_auxtrace_event(struct perf_session *session, > >> union perf_event *event, > >> struct perf_tool *tool __maybe_unused) > >> @@ -2462,7 +2478,8 @@ static int cs_etm__process_auxtrace_event(struct perf_session *session, > >> cs_etm__dump_event(etm, buffer); > >> auxtrace_buffer__put_data(buffer); > >> } > >> - } > >> + } else if (dump_trace) > >> + dump_queued_data(etm, &event->auxtrace); > > > > IIUC, in the function cs_etm__process_auxtrace_event(), since > > "etm->data_queued" is always true, below flow will never run: > > > > if (!etm->data_queued) { > > ...... > > > > if (dump_trace) > > if (auxtrace_buffer__get_data(buffer, fd)) { > > cs_etm__dump_event(etm, buffer); > > auxtrace_buffer__put_data(buffer); > > } > > } > > > > If so, it's better to use a new patch to polish the code. > > > > Hi Leo, > > I think this is not true in piped mode because there is no auxtrace index. > In that mode, events are processed only in file order and cs_etm__process_auxtrace_event() > is called for each buffer. > > You can reproduce this with something like this: > > ./perf record -o - ls > stdio.data > cat stdio.data | ./perf report -i -
You are right! I tried these two commands with cs_etm event, just as you said, in this case, the AUX trace data is not queued; so the flow for "if (!etm->data_queued)" should be kept. If so, I am very fine for current change. Thanks for sharing the knowledge.
> There are some other Coresight features that don't work as expected in this mode, like > sorting timestamps between CPUs. The aux split patchset won't work either because random > access isn't possible. And the TRBE patch that I'm working on now won't work, because it > also requires the random access to lookup the flags on the AUX record to configure the > decoder for unformatted trace.
Cool, looking forward for the patches :)
Leo
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