Em Thu, Jan 09, 2014 at 05:17:27PM +0900, Namhyung Kim escreveu:
> Hi Vince,
>
> On Wed, 8 Jan 2014 16:30:17 -0500 (EST), Vince Weaver wrote:
> > just checking on the status of this patch. Am I sending it to the wrong
> > place? Did it get lost in the post-holiday e-mail purges?
> >
> > The bug is annoying if you're trying to use perf on ARM systems.
>
> Right, acme, would you please merge this?
I will, but having a patch authored by someone and Acked-by that same
person looks weird, so, to clarify, this was written by Vince, acked by
you, right?
- Arnaldo
> Thanks,
> Namhyung
>
> >
> > On Mon, 30 Dec 2013, Vince Weaver wrote:
> >
> >>
> >> "perf list" listing of hardware events doesn't work on older ARM devices.
> >> The change enabling event detection:
> >>
> >> commit b41f1cec91c37eeea6fdb15effbfa24ea0a5536b
> >> Author: Namhyung Kim <namhyung....@lge.com>
> >> Date: Tue Aug 27 11:41:53 2013 +0900
> >>
> >> perf list: Skip unsupported events
> >>
> >>
> >> uses the following code in tools/perf/util/parse-events.c:
> >>
> >> struct perf_event_attr attr = {
> >> .type = type,
> >> .config = config,
> >> .disabled = 1,
> >> .exclude_kernel = 1,
> >> };
> >>
> >> On ARM machines pre-dating the Cortex-A15 this doesn't work, as
> >> these machines don't support .exclude_kernel. So starting with 3.12
> >> "perf list" does not report any hardware events at all on older
> >> machines (seen on Rasp-Pi, Pandaboard, Beagleboard, etc).
> >>
> >> This version of the patch makes changes suggested by Namhyung Kim
> >> to check for EACCESS and retry (instead of just dropping
> >> the exclude_kernel) so we can properly handle machines where
> >> /proc/sys/kernel/perf_event_paranoid is set to 2.
> >>
> >> Reported-by: Chad Paradis <chad.para...@umit.maine.edu>
> >> Signed-off-by: Vince Weaver <vincent.wea...@maine.edu>
> >> Acked-by: Namhyung Kim <namhy...@kernel.org>
> >>
> >> diff --git a/tools/perf/util/parse-events.c
> >> b/tools/perf/util/parse-events.c
> >> index 6de6f89..1fa98b9 100644
> >> --- a/tools/perf/util/parse-events.c
> >> +++ b/tools/perf/util/parse-events.c
> >> @@ -1082,12 +1082,12 @@ int is_valid_tracepoint(const char *event_string)
> >> static bool is_event_supported(u8 type, unsigned config)
> >> {
> >> bool ret = true;
> >> + int open_return;
> >> struct perf_evsel *evsel;
> >> struct perf_event_attr attr = {
> >> .type = type,
> >> .config = config,
> >> .disabled = 1,
> >> - .exclude_kernel = 1,
> >> };
> >> struct {
> >> struct thread_map map;
> >> @@ -1099,7 +1099,20 @@ static bool is_event_supported(u8 type, unsigned
> >> config)
> >>
> >> evsel = perf_evsel__new(&attr);
> >> if (evsel) {
> >> - ret = perf_evsel__open(evsel, NULL, &tmap.map) >= 0;
> >> + open_return = perf_evsel__open(evsel, NULL, &tmap.map);
> >> + ret = open_return >= 0;
> >> +
> >> + if (open_return == -EACCES) {
> >> + /*
> >> + * This happens if the paranoid value
> >> + * /proc/sys/kernel/perf_event_paranoid is set to 2
> >> + * Re-run with exclude_kernel set; we don't do that
> >> + * by default as some ARM machines do not support it.
> >> + *
> >> + */
> >> + evsel->attr.exclude_kernel = 1;
> >> + ret = perf_evsel__open(evsel, NULL, &tmap.map) >= 0;
> >> + }
> >> perf_evsel__delete(evsel);
> >> }
> >>
> >>
> >
> > Vince Weaver
> > vincent.wea...@maine.edu
> > http://www.eece.maine.edu/~vweaver/
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