Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.35 as permitted sender) client-ip=23.128.96.35;
MIME-Version: 1.0
References: <20231208210855.407580-1-kan.liang@linux.intel.com>
In-Reply-To: <20231208210855.407580-1-kan.liang@linux.intel.com>
From:   Ian Rogers <irogers@google.com>
Date:   Mon, 11 Dec 2023 16:02:37 -0800
Message-ID: <CAP-5=fWmy7+iNRpMAZ_So0ki8oOD_4RSn9Mx+gGroWZH6_7Sdw@mail.gmail.com>
Subject: Re: [PATCH] perf top: Use evsel's cpus to replace user_requested_cpus
To:     kan.liang@linux.intel.com
Cc:     acme@kernel.org, namhyung@kernel.org, mark.rutland@arm.com,
        maz@kernel.org, marcan@marcan.st, linux-kernel@vger.kernel.org,
        linux-perf-users@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

On Fri, Dec 8, 2023 at 1:09=E2=80=AFPM <kan.liang@linux.intel.com> wrote:
>
> From: Kan Liang <kan.liang@linux.intel.com>
>
> perf top errors out on a hybrid machine
>  $perf top
>
>  Error:
>  The cycles:P event is not supported.
>
> The user_requested_cpus may contain CPUs that are invalid for a hybrid
> PMU. It causes perf_event_open to fail.
>
> The commit ef91871c960e ("perf evlist: Propagate user CPU maps
> intersecting core PMU maps") already intersect the requested CPU map
> with the CPU map of the PMU. Use the evsel's cpus to replace
> user_requested_cpus.
>
> The evlist's threads is also propagated to evsel's threads in
> __perf_evlist__propagate_maps(). Replace it as well.
>
> Reported-by: Arnaldo Carvalho de Melo <acme@kernel.org>
> Closes: https://lore.kernel.org/linux-perf-users/ZXNnDrGKXbEELMXV@kernel.=
org/
> Signed-off-by: Kan Liang <kan.liang@linux.intel.com>

Sorry I missed top doing the evlist__create_maps calls:
https://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git/tr=
ee/tools/perf/builtin-top.c?h=3Dperf-tools-next#n1761
so it is right that the only divergence from record:
https://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git/tr=
ee/tools/perf/builtin-record.c?h=3Dperf-tools-next#n1362
and stat:
https://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git/tr=
ee/tools/perf/util/stat.c?h=3Dperf-tools-next#n797
So this is the right fix I believe.

Reviewed-by: Ian Rogers <irogers@google.com>

Thanks,
Ian

> ---
>  tools/perf/builtin-top.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
> index ea8c7eca5eee..cce9350177e2 100644
> --- a/tools/perf/builtin-top.c
> +++ b/tools/perf/builtin-top.c
> @@ -1027,8 +1027,8 @@ static int perf_top__start_counters(struct perf_top=
 *top)
>
>         evlist__for_each_entry(evlist, counter) {
>  try_again:
> -               if (evsel__open(counter, top->evlist->core.user_requested=
_cpus,
> -                                    top->evlist->core.threads) < 0) {
> +               if (evsel__open(counter, counter->core.cpus,
> +                               counter->core.threads) < 0) {
>
>                         /*
>                          * Specially handle overwrite fall back.
> --
> 2.35.1
>