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Date: Fri, 28 Oct 2022 16:45:42 -0300 From: Arnaldo Carvalho de Melo <acme@...nel.org> To: Ian Rogers <irogers@...gle.com> Cc: John Garry <john.garry@...wei.com>, Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, Mark Rutland <mark.rutland@....com>, Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, Namhyung Kim <namhyung@...nel.org>, linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org, Ravi Bangoria <ravi.bangoria@....com>, Stephane Eranian <eranian@...gle.com> Subject: Re: [PATCH v1] perf test: Parse events workaround for dash/minus Em Fri, Oct 28, 2022 at 10:55:14AM -0700, Ian Rogers escreveu: > On Mon, Oct 17, 2022 at 4:07 PM Ian Rogers <irogers@...gle.com> wrote: > > > > On Thu, Oct 13, 2022 at 5:11 AM John Garry <john.garry@...wei.com> wrote: > > > > > > On 13/10/2022 02:12, Ian Rogers wrote: > > > > Skip an event configuration for event names with a dash/minus in them. > > > > Events with a dash/minus in their name cause parsing issues as legacy > > > > encoding of events would use a dash/minus as a separator. The parser > > > > separates events with dashes into prefixes and suffixes and then > > > > recombines them. Unfortunately if an event has part of its name that > > > > matches a legacy token then the recombining fails. This is seen for > > > > branch-brs where branch is a legacy token. branch-brs was introduced > > > > to sysfs in: > > > > https://lore.kernel.org/all/20220322221517.2510440-5-eranian@google.com/ > > > > The failure is shown below as well as the workaround to use a config > > > > where the dash/minus isn't treated specially: > > > > > > > > ``` > > > > $ perf stat -e branch-brs true > > > > event syntax error: 'branch-brs' > > > > \___ parser error > > > > > > > > $ perf stat -e cpu/branch-brs/ true > > > > > > > > Performance counter stats for 'true': > > > > > > > > 46,179 cpu/branch-brs/ > > > > ``` > > > > > > > > Signed-off-by: Ian Rogers <irogers@...gle.com> > > > > --- > > > > tools/perf/tests/parse-events.c | 13 +++++++++++++ > > > > 1 file changed, 13 insertions(+) > > > > > > > > diff --git a/tools/perf/tests/parse-events.c b/tools/perf/tests/parse-events.c > > > > index 459afdb256a1..3440dd2616b0 100644 > > > > --- a/tools/perf/tests/parse-events.c > > > > +++ b/tools/perf/tests/parse-events.c > > > > @@ -2237,6 +2237,19 @@ static int test__pmu_events(struct test_suite *test __maybe_unused, int subtest > > > > pr_debug("Test PMU event failed for '%s'", name); > > > > ret = combine_test_results(ret, test_ret); > > > > > > > > > > Hi Ian, > > > > > > } > > > > + /* > > > > + * Names containing '-' are recognized as prefixes and suffixes > > > > + * due to '-' being a legacy PMU separator. This fails when the > > > > + * prefix or suffix collides with an existing legacy token. For > > > > + * example, branch-brs has a prefix (branch) that collides with > > > > + * a PE_NAME_CACHE_TYPE token causing a parse error as a suffix > > > > + * isn't expected after this. > > > > > > OK, so you want to skip anything with '-'. Will we now miss out on > > > events which contain a '-' but don't clash with an existing legacy token? > > > > Yes. The long term solution here is to ditch the current parse event > > code and its legacy support. An idea is to create a simplified parser > > as part of libperf2 (libperf but with a libbpf style license), use the > > new parser for metrics and events. In the events case, if the new > > parser fails then use the legacy parser and its weird handling of > > dashes. > > > > > > As event names in the config > > > > + * slashes are allowed a '-' in the name we check this works > > > > + * above. > > > > > > Sorry, I can't follow what you mean here. Do you mean that > > > "cpu/branch-brs/" works ok and we continue to test it? > > > > Yep, as shown in the commit message. The comment isn't great, it > > should be worded something like: > > > > If an event name is in the config slashes, such as cpu/branch-brs/, a > > '-' in the name works as the dash doesn't separate the parts of the > > name. This continues to be tested above. > > Ping. It'd be nice to merge this as otherwise we have a perf test > failure on AMD. I added it for perf/core, i.e. 6.2. Thanks, - Arnaldo
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