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Message-ID: <cc4ac58b-6a0b-1d72-f881-a60b43d5c229@huawei.com>
Date: Wed, 12 Jun 2024 18:16:14 +0800
From: Yicong Yang <yangyicong@...wei.com>
To: Ian Rogers <irogers@...gle.com>, Suzuki K Poulose
<suzuki.poulose@....com>, Mike Leach <mike.leach@...aro.org>, James Clark
<james.clark@....com>, John Garry <john.g.garry@...cle.com>, Will Deacon
<will@...nel.org>, Leo Yan <leo.yan@...ux.dev>, Peter Zijlstra
<peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, Arnaldo Carvalho de
Melo <acme@...nel.org>, Namhyung Kim <namhyung@...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>,
<coresight@...ts.linaro.org>, <linux-arm-kernel@...ts.infradead.org>,
<linux-perf-users@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC: <yangyicong@...ilicon.com>
Subject: Re: [PATCH v1] perf arm: Workaround ARM PMUs cpu maps having offline
cpus
Hi Ian,
On 2024/6/7 14:53, Ian Rogers wrote:
> When PMUs have a cpu map in the 'cpus' or 'cpumask' file, perf will
> try to open events on those CPUs. ARM doesn't remove offline CPUs
> meaning taking a CPU offline will cause perf commands to fail unless a
> CPU map is passed on the command line.
>
> More context in:
> https://lore.kernel.org/lkml/20240603092812.46616-1-yangyicong@huawei.com/
>
> Reported-by: Yicong Yang <yangyicong@...wei.com>
> Closes: https://lore.kernel.org/lkml/20240603092812.46616-2-yangyicong@huawei.com/
> Signed-off-by: Ian Rogers <irogers@...gle.com>
Tested worked for this case:
[root@...alhost tmp]# echo 0 > /sys/devices/system/cpu/cpu1/online
[root@...alhost tmp]# /home/yang/perf_static stat -e armv8_pmuv3_0/cpu_cycles/ --timeout 100
Error:
The sys_perf_event_open() syscall returned with 19 (No such device) for event (armv8_pmuv3_0/cpu_cycles/).
/bin/dmesg | grep -i perf may provide additional information.
[root@...alhost tmp]# /tmp/perf_Ian stat -e armv8_pmuv3_0/cpu_cycles/ --timeout 100
Performance counter stats for 'system wide':
54994604 armv8_pmuv3_0/cpu_cycles/
0.176079800 seconds time elapsed
So:
Tested-by: Yicong Yang <yangyicong@...ilicon.com>
But still wondering why isn't it better to move this into pmu_cpumask() as does in
the previous patch? Yes currently this is a arm specific issue, but we cannot handle
the case if later PMU doesn't update the cpus/cpumask either :)
> ---
> tools/perf/arch/arm/util/pmu.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/tools/perf/arch/arm/util/pmu.c b/tools/perf/arch/arm/util/pmu.c
> index 8b7cb68ba1a8..6b544edbd3f6 100644
> --- a/tools/perf/arch/arm/util/pmu.c
> +++ b/tools/perf/arch/arm/util/pmu.c
> @@ -11,12 +11,15 @@
>
> #include "arm-spe.h"
> #include "hisi-ptt.h"
> +#include "../../../util/cpumap.h"
> #include "../../../util/pmu.h"
> #include "../../../util/cs-etm.h"
> #include "../../arm64/util/mem-events.h"
>
> -void perf_pmu__arch_init(struct perf_pmu *pmu __maybe_unused)
> +void perf_pmu__arch_init(struct perf_pmu *pmu)
> {
> + struct perf_cpu_map *intersect;
> +
> #ifdef HAVE_AUXTRACE_SUPPORT
> if (!strcmp(pmu->name, CORESIGHT_ETM_PMU_NAME)) {
> /* add ETM default config here */
> @@ -33,6 +36,9 @@ void perf_pmu__arch_init(struct perf_pmu *pmu __maybe_unused)
> pmu->selectable = true;
> #endif
> }
> -
> #endif
> + /* Workaround some ARM PMU's failing to correctly set CPU maps for online processors. */
> + intersect = perf_cpu_map__intersect(cpu_map__online(), pmu->cpus);
> + perf_cpu_map__put(pmu->cpus);
> + pmu->cpus = intersect;
> }
>
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