perf pmu: Skip invalid hybrid pmu

On hybrid platform, such as Alderlake, if atom CPUs are offlined,
the kernel still exports the sysfs path '/sys/devices/cpu_atom/' for
'cpu_atom' pmu but the file '/sys/devices/cpu_atom/cpus' is empty,
which indicates this is an invalid pmu.

Need to check and skip the invalid hybrid pmu.

Before:

  # perf list
  ...
  branch-instructions OR cpu_atom/branch-instructions/ [Kernel PMU event]
  branch-instructions OR cpu_core/branch-instructions/ [Kernel PMU event]
  branch-misses OR cpu_atom/branch-misses/           [Kernel PMU event]
  branch-misses OR cpu_core/branch-misses/           [Kernel PMU event]
  bus-cycles OR cpu_atom/bus-cycles/                 [Kernel PMU event]
  bus-cycles OR cpu_core/bus-cycles/                 [Kernel PMU event]
  ...

The cpu_atom events are still displayed even if atom CPUs are offlined.

After:

  # perf list
  ...
  branch-instructions OR cpu_core/branch-instructions/ [Kernel PMU event]
  branch-misses OR cpu_core/branch-misses/           [Kernel PMU event]
  bus-cycles OR cpu_core/bus-cycles/                 [Kernel PMU event]
  ...

Now only cpu_core events are displayed.

Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jin Yao <yao.jin@intel.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20210708013701.20347-2-yao.jin@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index 44b90d638ad5f1a1d7d6411addb35c351a1bd63c..a1bd7007a8b4d6257181ee92509e7bb9fa5347a4 100644 (file)
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -950,6 +950,13 @@ static struct perf_pmu *pmu_lookup(const char *name)
        LIST_HEAD(format);
        LIST_HEAD(aliases);
        __u32 type;
+       bool is_hybrid = perf_pmu__hybrid_mounted(name);
+
+       /*
+        * Check pmu name for hybrid and the pmu may be invalid in sysfs
+        */
+       if (!strncmp(name, "cpu_", 4) && !is_hybrid)
+               return NULL;
 
        /*
         * The pmu data we store & need consists of the pmu
@@ -978,7 +985,7 @@ static struct perf_pmu *pmu_lookup(const char *name)
        pmu->is_uncore = pmu_is_uncore(name);
        if (pmu->is_uncore)
                pmu->id = pmu_id(name);
-       pmu->is_hybrid = perf_pmu__hybrid_mounted(name);
+       pmu->is_hybrid = is_hybrid;
        pmu->max_precise = pmu_max_precise(name);
        pmu_add_cpu_aliases(&aliases, pmu);
        pmu_add_sys_aliases(&aliases, pmu);