perf perf_api_probe: Avoid scanning all PMUs, try software PMU first

Scan the software PMU first rather than last as it is the least likely
to fail the probe. Specifying the software PMU by name was enabled by
commit 9957d8c801fe ("perf jevents: Add common software event
json"). For hardware events, add core PMU names when getting events to
probe so that not all PMUs are scanned. For example, when legacy
events support wildcards and for the event "cycles:u" on x86, we want
to only scan the "cpu" PMU and not all uncore PMUs for the event too.

Tested-by: Thomas Richter <tmricht@linux.ibm.com>
Signed-off-by: Ian Rogers <irogers@google.com>
Tested-by: James Clark <james.clark@linaro.org>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

diff --git a/tools/perf/util/perf_api_probe.c b/tools/perf/util/perf_api_probe.c
index 1de3b69cdf4aafb7fdc73574b2b44a3cad38a75e..6ecf38314f01c61123dbc6d9c0b4d968d54ed5cc 100644 (file)
--- a/tools/perf/util/perf_api_probe.c
+++ b/tools/perf/util/perf_api_probe.c
@@ -59,10 +59,10 @@ out_delete:
 
 static bool perf_probe_api(setup_probe_fn_t fn)
 {
-       const char *try[] = {"cycles:u", "instructions:u", "cpu-clock:u", NULL};
+       struct perf_pmu *pmu;
        struct perf_cpu_map *cpus;
        struct perf_cpu cpu;
-       int ret, i = 0;
+       int ret = 0;
 
        cpus = perf_cpu_map__new_online_cpus();
        if (!cpus)
@@ -70,12 +70,23 @@ static bool perf_probe_api(setup_probe_fn_t fn)
        cpu = perf_cpu_map__cpu(cpus, 0);
        perf_cpu_map__put(cpus);
 
-       do {
-               ret = perf_do_probe_api(fn, cpu, try[i++]);
-               if (!ret)
-                       return true;
-       } while (ret == -EAGAIN && try[i]);
-
+       ret = perf_do_probe_api(fn, cpu, "software/cpu-clock/u");
+       if (!ret)
+               return true;
+
+       pmu = perf_pmus__scan_core(/*pmu=*/NULL);
+       if (pmu) {
+               const char *try[] = {"cycles", "instructions", NULL};
+               char buf[256];
+               int i = 0;
+
+               while (ret == -EAGAIN && try[i]) {
+                       snprintf(buf, sizeof(buf), "%s/%s/u", pmu->name, try[i++]);
+                       ret = perf_do_probe_api(fn, cpu, buf);
+                       if (!ret)
+                               return true;
+               }
+       }
        return false;
 }