Commit 292c34c1 authored Apr 24, 2018 by Kan Liang Committed by Arnaldo Carvalho de Melo Apr 24, 2018

perf pmu: Fix core PMU alias list for X86 platform



When counting uncore event with alias, core event is mistakenly
involved, for example:

  perf stat --no-merge -e "unc_m_cas_count.all" -C0  sleep 1

  Performance counter stats for 'CPU(s) 0':

                 0      unc_m_cas_count.all [uncore_imc_4]
                 0      unc_m_cas_count.all [uncore_imc_2]
                 0      unc_m_cas_count.all [uncore_imc_0]
           153,640      unc_m_cas_count.all [cpu]
                 0      unc_m_cas_count.all [uncore_imc_5]
            25,026      unc_m_cas_count.all [uncore_imc_3]
                 0      unc_m_cas_count.all [uncore_imc_1]

       1.001447890 seconds time elapsed

The reason is that current implementation doesn't check PMU name of a
event when adding its alias into the alias list for core PMU. The
uncore event aliases are mistakenly added.

This bug was introduced in:
  commit 14b22ae0 ("perf pmu: Add helper function is_pmu_core to
  detect PMU CORE devices")

Checking the PMU name for all PMUs on X86 and other architectures except
ARM.
There is no behavior change for ARM.

Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Agustin Vega-Frias <agustinv@codeaurora.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ganapatrao Kulkarni <ganapatrao.kulkarni@cavium.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Shaokun Zhang <zhangshaokun@hisilicon.com>
Cc: Will Deacon <will.deacon@arm.com>
Fixes: 14b22ae0 ("perf pmu: Add helper function is_pmu_core to detect PMU CORE devices")
Link: http://lkml.kernel.org/r/1524594014-79243-1-git-send-email-kan.liang@linux.intel.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

parent 5d9946c3

tools/perf/util/pmu.c

+7 −13

Original line number	Diff line number	Diff line
		@@ -539,9 +539,10 @@ static bool pmu_is_uncore(const char *name)

		/*
		* PMU CORE devices have different name other than cpu in sysfs on some
		* platforms. looking for possible sysfs files to identify as core device.
		* platforms.
		* Looking for possible sysfs files to identify the arm core device.
		*/
		static int is_pmu_core(const char *name)
		static int is_arm_pmu_core(const char *name)
		{
		struct stat st;
		char path[PATH_MAX];
		@@ -550,12 +551,6 @@ static int is_pmu_core(const char *name)
		if (!sysfs)
		return 0;

		/* Look for cpu sysfs (x86 and others) */
		scnprintf(path, PATH_MAX, "%s/bus/event_source/devices/cpu", sysfs);
		if ((stat(path, &st) == 0) &&
		(strncmp(name, "cpu", strlen("cpu")) == 0))
		return 1;

		/* Look for cpu sysfs (specific to arm) */
		scnprintf(path, PATH_MAX, "%s/bus/event_source/devices/%s/cpus",
		sysfs, name);
		@@ -668,6 +663,7 @@ static void pmu_add_cpu_aliases(struct list_head head, struct perf_pmu pmu)
		struct pmu_events_map *map;
		struct pmu_event *pe;
		const char *name = pmu->name;
		const char *pname;

		map = perf_pmu__find_map(pmu);
		if (!map)
		@@ -686,11 +682,9 @@ static void pmu_add_cpu_aliases(struct list_head head, struct perf_pmu pmu)
		break;
		}

		if (!is_pmu_core(name)) {
		/* check for uncore devices */
		if (pe->pmu == NULL)
		continue;
		if (strncmp(pe->pmu, name, strlen(pe->pmu)))
		if (!is_arm_pmu_core(name)) {
		pname = pe->pmu ? pe->pmu : "cpu";
		if (strncmp(pname, name, strlen(pname)))
		continue;
		}