linux-kernel - Re: [PATCH V2] perf tools: adding support for address filters

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Message-ID: <20160831184059.GD32396@krava>
Date:   Wed, 31 Aug 2016 20:40:59 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     Mathieu Poirier <mathieu.poirier@...aro.org>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        jolsa@...nel.org, Arnaldo Carvalho de Melo <acme@...radead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH V2] perf tools: adding support for address filters

On Wed, Aug 31, 2016 at 10:30:16AM -0600, Mathieu Poirier wrote:
> On 31 August 2016 at 00:57, Jiri Olsa <jolsa@...hat.com> wrote:
> > On Tue, Aug 30, 2016 at 10:10:15AM -0600, Mathieu Poirier wrote:
> >> This patch makes it possible to use the current filter
> >> framework with address filters.  That way address filters for
> >> HW tracers such as CoreSight and IntelPT can be communicated
> >> to the kernel drivers.
> >>
> >> CC: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
> >> Signed-off-by: Mathieu Poirier <mathieu.poirier@...aro.org>
> >>
> >> ---
> >> Changes for V2:
> >>  - Rebased to v4.8-rc4.
> >>  - Revisited error path.
> >> ---
> >>
> >>  tools/perf/util/parse-events.c | 30 +++++++++++++++++++++++++-----
> >>  1 file changed, 25 insertions(+), 5 deletions(-)
> >>
> >> diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
> >> index 2eb8b1ed4cc8..1df413fbf7f8 100644
> >> --- a/tools/perf/util/parse-events.c
> >> +++ b/tools/perf/util/parse-events.c
> >> @@ -1760,12 +1760,26 @@ foreach_evsel_in_last_glob(struct perf_evlist *evlist,
> >>  static int set_filter(struct perf_evsel *evsel, const void *arg)
> >>  {
> >>       const char *str = arg;
> >> +     bool found = false;
> >> +     int nr_addr_filters = 0;
> >> +     struct perf_pmu *pmu = NULL;
> >>
> >> -     if (evsel == NULL || evsel->attr.type != PERF_TYPE_TRACEPOINT) {
> >> -             fprintf(stderr,
> >> -                     "--filter option should follow a -e tracepoint option\n");
> >> -             return -1;
> >> -     }
> >> +     if (evsel == NULL)
> >> +             goto err;
> >> +
> >> +     while ((pmu = perf_pmu__scan(pmu)) != NULL)
> >> +             if (pmu->type == evsel->attr.type) {
> >> +                     found = true;
> >> +                     break;
> >> +             }
> >> +
> >> +     if (found)
> >> +             perf_pmu__scan_file(pmu, "nr_addr_filters",
> >> +                                 "%d", &nr_addr_filters);
> >> +
> >> +
> >> +     if (evsel->attr.type != PERF_TYPE_TRACEPOINT && !nr_addr_filters)
> >> +             goto err;
> >
> > should we display another error message for !nr_addr_filters case?
> > the one below is misleading in this case
> 
> The condition where nr_addr_filters == 0 is valid when we are dealing
> with a tracepoint event.  Since we don't have an attribute type for HW
> tracers the best we can do is improve on the error message.  What
> would you think of:
> 
> "--filter option should follow an event that supports filtering"

ok, in this case I think the original one is better

Acked-by: Jiri Olsa <jolsa@...nel.org>

thanks,
jirka