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Subject[PATCH 09/12] perf pmu: Fix core PMU alias list for X86 platform
Date
From: Kan Liang <kan.liang@linux.intel.com>

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 14b22ae028de ("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: 14b22ae028de ("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>
---
tools/perf/util/pmu.c | 20 +++++++-------------
1 file changed, 7 insertions(+), 13 deletions(-)

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index af4bedf4cf98..d2fb597c9a8c 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -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;
}

--
2.14.3
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