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Message-ID: <CAP-5=fWdKNT2sLXeRj7r-WpsE2Xg7ZTOxVKy6D_Cg_NYA0AXGQ@mail.gmail.com>
Date: Wed, 5 Mar 2025 00:39:09 -0800
From: Ian Rogers <irogers@...gle.com>
To: Dapeng Mi <dapeng1.mi@...ux.intel.com>
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>,
Adrian Hunter <adrian.hunter@...el.com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Kan Liang <kan.liang@...ux.intel.com>,
linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
Dapeng Mi <dapeng1.mi@...el.com>
Subject: Re: [PATCH 2/2] perf tools/tests: Fix topdown groups test on hybrid platforms
On Tue, Mar 4, 2025 at 10:07 PM Ian Rogers <irogers@...gle.com> wrote:
>
> On Sun, Feb 23, 2025 at 5:43 PM Dapeng Mi <dapeng1.mi@...ux.intel.com> wrote:
> >
> > When running topdown groups test on hybrid platforms like LNL/ARL, we
> > see the following 2 commands fail.
> >
> > perf stat $cputype -e '{instructions,slots},topdown-retiring' true
> > perf stat $cputype -e '{instructions,slots},{topdown-retiring}' true
> >
> > Take the 1st command as an example, 5 events are created on hybrid
> > platform. They are cpu_atom/instructions/, cpu_core/instructions/,
> > cpu_core/slots/, cpu_atom/topdown-retiring/ and
> > cpu_core/topdown-retiring/ events. The former 3 events are in a group
> > and the latter 2 topdown-retiring events are independent events.
> >
> > As the limitation of current implementation, the
> > cpu_core/topdown-retiring/ event can't be moved into previous group as
> > long as there are other events before it. That's the reason why we see
> > the failure.
> >
> > Thus add "--cputype core" option to limit only P-core events are tested.
> >
> > Signed-off-by: Dapeng Mi <dapeng1.mi@...ux.intel.com>
> > ---
> > tools/perf/arch/x86/util/evlist.c | 26 +++++++++++++++++++++++---
> > tools/perf/tests/shell/stat.sh | 20 ++++++++++++++++++--
> > 2 files changed, 41 insertions(+), 5 deletions(-)
> >
> > diff --git a/tools/perf/arch/x86/util/evlist.c b/tools/perf/arch/x86/util/evlist.c
> > index 447a734e591c..0a71ba975871 100644
> > --- a/tools/perf/arch/x86/util/evlist.c
> > +++ b/tools/perf/arch/x86/util/evlist.c
> > @@ -9,7 +9,7 @@ int arch_evlist__cmp(const struct evsel *lhs, const struct evsel *rhs)
> > {
> > /*
> > * Currently the following topdown events sequence are supported to
> > - * move and regroup correctly.
> > + * move and regroup correctly on non-hybrid platforms.
> > *
> > * a. all events in a group
> > * perf stat -e "{instructions,topdown-retiring,slots}" -C0 sleep 1
> > @@ -44,7 +44,7 @@ int arch_evlist__cmp(const struct evsel *lhs, const struct evsel *rhs)
> > * 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
> > + * e. 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
> > @@ -56,11 +56,31 @@ int arch_evlist__cmp(const struct evsel *lhs, const struct evsel *rhs)
> > * 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
> > + * f. perf stat -e "{instructions,slots},{topdown-retiring,cycles}" -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)
> > + *
> > + * For hybrid platforms, the sequences 'c' and 'd' are not supported as well
> > + * besides above sequences 'e' and 'f'.
> > + *
> > + * perf stat -e "{instructions,slots},topdown-retiring" -C0 sleep 1
> > + * perf stat -e "{instructions,slots},{topdown-retiring}" -C0 sleep 1
> > + *
> > + * On hybrid platforms each event would create an instance on all types of PMU
> > + * if the event can be supported by the PMU, i.e., the "topdown-retiring" event
> > + * would create two instances on hybrid platforms with P-cores and E-cores,
> > + * "cpu_core/topdown-retiring/" and "cpu_atom/topdown_retiring".
> > + *
> > + * Take the first command as an example, the events list would be converted to
> > + * below list in fact.
> > + *
> > + * "{cpu_atom/instructions/,cpu_core/instructions/,cpu_core/slots/},
> > + * cpu_atom/topdown-retiring/,cpu_core/topdown-retiring/"
> > + *
> > + * This is actually same with event list in case 'e', "cpu_core/topdown-retiring/"
> > + * event can't be moved into previous events group.
> > */
> > if (topdown_sys_has_perf_metrics() &&
> > (arch_evsel__must_be_in_group(lhs) || arch_evsel__must_be_in_group(rhs))) {
> > diff --git a/tools/perf/tests/shell/stat.sh b/tools/perf/tests/shell/stat.sh
> > index 68323d636fb7..cdfe27c25528 100755
> > --- a/tools/perf/tests/shell/stat.sh
> > +++ b/tools/perf/tests/shell/stat.sh
> > @@ -5,6 +5,16 @@
> > set -e
> >
> > err=0
> > +is_hybrid=false
> > +
> > +check_hybrid_platform() {
> > + pmus=$(ls /sys/bus/event_source/devices/*/cpus 2>/dev/null | wc -l)
> > + if [ "$pmus" -gt 1 ]
> > + then
> > + is_hybrid=true
> > + fi
> > +}
> > +
> > test_default_stat() {
> > echo "Basic stat command test"
> > if ! perf stat true 2>&1 | grep -E -q "Performance counter stats for 'true':"
> > @@ -62,6 +72,11 @@ test_topdown_groups() {
> > # Topdown events must be grouped with the slots event first. Test that
> > # parse-events reorders this.
> > echo "Topdown event group test"
> > + cputype=""
> > + if $is_hybrid
> > + then
> > + cputype="--cputype core"
> > + fi
> > if ! perf stat -e '{slots,topdown-retiring}' true > /dev/null 2>&1
> > then
> > echo "Topdown event group test [Skipped event parsing failed]"
> > @@ -85,13 +100,13 @@ test_topdown_groups() {
> > err=1
> > return
> > fi
> > - if perf stat -e '{instructions,slots},topdown-retiring' true 2>&1 | grep -E -q "<not supported>"
> > + if perf stat $cputype -e '{instructions,slots},topdown-retiring' true 2>&1 | grep -E -q "<not supported>"
>
> So I can make this test fail on non-hybrid with:
> ```
> $ perf stat -e '{instructions,slots},faults,topdown-retiring' true
> WARNING: events were regrouped to match PMUs
>
> Performance counter stats for 'true':
>
> 5,312,770 slots
> 1,078,401 instructions
> 56 faults
> <not supported> topdown-retiring
> ```
> The issue is that the slots isn't a group leader, so the "force group
> index" we try to insert must be grouped events into is miscalculated
> to be topdown-retiring. The following fixes this:
> ```
> diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
> index 35e48fe56dfa..68ddc335cde4 100644
> --- a/tools/perf/util/parse-events.c
> +++ b/tools/perf/util/parse-events.c
> @@ -2056,8 +2056,7 @@ static int
> parse_events__sort_events_and_fix_groups(struct list_head *list)
> pos->core.idx = idx++;
>
> /* Remember an index to sort all forced grouped events
> together to. */
> - if (force_grouped_idx == -1 && pos == pos_leader &&
> pos->core.nr_members < 2 &&
> - arch_evsel__must_be_in_group(pos))
> + if (force_grouped_idx == -1 &&
> arch_evsel__must_be_in_group(pos))
> force_grouped_idx = pos->core.idx;
> }
> ```
>
> > then
> > echo "Topdown event group test [Failed topdown metrics event not move into slots group]"
> > err=1
> > return
> > fi
> > - if perf stat -e '{instructions,slots},{topdown-retiring}' true 2>&1 | grep -E -q "<not supported>"
> > + if perf stat $cputype -e '{instructions,slots},{topdown-retiring}' true 2>&1 | grep -E -q "<not supported>"
>
> So this is trickier as '{topdown-retiring}' ends up looking as a 2
> event group. I'll post a proposed fix.
Patch here:
https://lore.kernel.org/lkml/20250305083735.393333-2-irogers@google.com/
Thanks,
Ian
>
> > then
> > echo "Topdown event group test [Failed topdown metrics group not merge into slots group]"
> > err=1
> > @@ -200,6 +215,7 @@ test_hybrid() {
> > echo "hybrid test [Success]"
> > }
> >
> > +check_hybrid_platform
> > test_default_stat
> > test_stat_record_report
> > test_stat_record_script
> > --
> > 2.40.1
> >
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