linux-kernel - Re: [PATCH v2 4/5] perf x86 evlist: Update comments on topdown regrouping

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Message-ID: <Z9Dqwd_7pyj7Gvqj@google.com>
Date: Tue, 11 Mar 2025 19:00:33 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: "Mi, Dapeng" <dapeng1.mi@...ux.intel.com>
Cc: Ian Rogers <irogers@...gle.com>, Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Kan Liang <kan.liang@...ux.intel.com>,
	James Clark <james.clark@...aro.org>,
	Dominique Martinet <asmadeus@...ewreck.org>,
	Andi Kleen <ak@...ux.intel.com>, linux-perf-users@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Thomas Falcon <thomas.falcon@...el.com>
Subject: Re: [PATCH v2 4/5] perf x86 evlist: Update comments on topdown
 regrouping

On Tue, Mar 11, 2025 at 08:45:20AM +0800, Mi, Dapeng wrote:
> 
> On 3/11/2025 5:25 AM, Namhyung Kim wrote:
> > Hello,
> >
> > On Thu, Mar 06, 2025 at 06:39:05PM -0800, Ian Rogers wrote:
> >> From: Dapeng Mi <dapeng1.mi@...ux.intel.com>
> >>
> >> Update to remove comments about groupings not working and with the:
> >> ```
> >> perf stat -e "{instructions,slots},{cycles,topdown-retiring}"
> >> ```
> >> case that now works.
> >>
> >> Signed-off-by: Ian Rogers <irogers@...gle.com>
> > Dapeng, can I get your Signed-off-by here?
> >
> > Thanks,
> > Namhyung
> >
> >> ---
> >>  tools/perf/arch/x86/util/evlist.c | 27 ++++++---------------------
> >>  1 file changed, 6 insertions(+), 21 deletions(-)
> >>
> >> diff --git a/tools/perf/arch/x86/util/evlist.c b/tools/perf/arch/x86/util/evlist.c
> >> index ed205d1b207d..7905a28d7734 100644
> >> --- a/tools/perf/arch/x86/util/evlist.c
> >> +++ b/tools/perf/arch/x86/util/evlist.c
> >> @@ -39,28 +39,13 @@ int arch_evlist__cmp(const struct evsel *lhs, const struct evsel *rhs)
> >>  	 *         26,319,024      slots
> >>  	 *          2,427,791      instructions
> >>  	 *          2,683,508      topdown-retiring
> >> -	 *
> >> -	 * If slots event and topdown metrics events are not in same group, the
> >> -	 * topdown metrics events must be first event after the slots event group,
> >> -	 * otherwise topdown metrics events can't be regrouped correctly, e.g.
> >> -	 *
> >> -	 * a. perf stat -e "{instructions,slots},cycles,topdown-retiring" -C0 sleep 1
> >> -	 *    WARNING: events were regrouped to match PMUs
> >> -	 *     Performance counter stats for 'CPU(s) 0':
> >> -	 *         17,923,134      slots
> >> -	 *          2,154,855      instructions
> >> -	 *          3,015,058      cycles
> >> -	 *    <not supported>      topdown-retiring
> >> -	 *
> >> -	 * If slots event and topdown metrics events are in two groups, the group which
> >> -	 * has topdown metrics events must contain only the topdown metrics event,
> >> -	 * otherwise topdown metrics event can't be regrouped correctly as well, e.g.
> >> -	 *
> >> -	 * a. perf stat -e "{instructions,slots},{topdown-retiring,cycles}" -C0 sleep 1
> >> +	 * e. slots event and metrics event are in a group and not adjacent
> 
> Yes, here is my SoB.
> 
> Signed-off-by: Dapeng Mi <dapeng1.mi@...ux.intel.com>

Thanks!

> 
> BTW, It seems there is a typo and missed the "not" word. It should be 
> "slots event and metrics event are not in a group and not adjacent"
 
Ok, will update.

Thanks,
Namhyung

> 
> >> +	 *    perf stat -e "{instructions,slots},cycles,topdown-retiring" -C0 sleep 1
> >>  	 *    WARNING: events were regrouped to match PMUs
> >> -	 *    Error:
> >> -	 *    The sys_perf_event_open() syscall returned with 22 (Invalid argument) for
> >> -	 *    event (topdown-retiring)
> >> +	 *         68,433,522      slots
> >> +	 *          8,856,102      topdown-retiring
> >> +	 *          7,791,494      instructions
> >> +	 *         11,469,513      cycles
> >>  	 */
> >>  	if (topdown_sys_has_perf_metrics() &&
> >>  	    (arch_evsel__must_be_in_group(lhs) || arch_evsel__must_be_in_group(rhs))) {
> >> -- 
> >> 2.49.0.rc0.332.g42c0ae87b1-goog
> >>