perf stat: Add per-core aggregation

This patch adds the --per-core option to perf stat.

This option is used to aggregate system-wide counts
on a per physical core basis. On processors with
hyperthreading, this means counts of all HT threads
running on a physical core are aggregated.

This mode is useful to find imblance between physical
cores running an uniform workload. Cores are identified
by socket: S0-C1, means physical core 1 on socket 0. Note
that cores are identified using their physical core id,
thus their numbering may not be continuous.

Per core aggregation can be combined with interval printing:

 # perf stat -a --per-core -I 1000 -e cycles sleep 1000
 #           time core         cpus             counts events
      1.000090030 S0-C0           1          4,765,747 cycles
      1.000090030 S0-C1           1          5,580,647 cycles
      1.000090030 S0-C2           1            221,181 cycles
      1.000090030 S0-C3           1            266,092 cycles

Signed-off-by: Stephane Eranian <eranian@google.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1360846649-6411-4-git-send-email-eranian@google.com
[ committer note: Remove parts already applied on 86ee6e1 to keep bisectability ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

4 files changed, 92 insertions, 3 deletions

diff --git a/tools/perf/Documentation/perf-stat.txt b/tools/perf/Documentation/perf-stat.txt
index 46027e1aedb7..2fe87fb558f0 100644
--- a/tools/perf/Documentation/perf-stat.txt
+++ b/tools/perf/Documentation/perf-stat.txt
@@ -126,6 +126,12 @@ use --per-socket in addition to -a. (system-wide).  The output includes the
 socket number and the number of online processors on that socket. This is
 useful to gauge the amount of aggregation.
 
+--per-core::
+Aggregate counts per physical processor for system-wide mode measurements.  This
+is a useful mode to detect imbalance between physical cores.  To enable this mode,
+use --per-core in addition to -a. (system-wide).  The output includes the
+core number and the number of online logical processors on that physical processor.
+
 EXAMPLES
 --------
 
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 6f6ea931ab76..7e910bab1097 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -80,6 +80,7 @@ enum aggr_mode {
         AGGR_NONE,
         AGGR_GLOBAL,
         AGGR_SOCKET,
+        AGGR_CORE,
 };
 
 static int                      run_count                       =  1;
@@ -384,6 +385,9 @@ static void print_interval(void)
                 case AGGR_SOCKET:
                         fprintf(output, "#           time socket cpus             counts events\n");
                         break;
+                case AGGR_CORE:
+                        fprintf(output, "#           time core         cpus             counts events\n");
+                        break;
                 case AGGR_NONE:
                         fprintf(output, "#           time CPU                 counts events\n");
                         break;
@@ -397,6 +401,7 @@ static void print_interval(void)
                 num_print_interval = 0;
 
         switch (aggr_mode) {
+        case AGGR_CORE:
         case AGGR_SOCKET:
                 print_aggr(prefix);
                 break;
@@ -566,13 +571,23 @@ static void print_noise(struct perf_evsel *evsel, double avg)
         print_noise_pct(stddev_stats(&ps->res_stats[0]), avg);
 }
 
-static void aggr_printout(struct perf_evsel *evsel, int cpu, int nr)
+static void aggr_printout(struct perf_evsel *evsel, int id, int nr)
 {
         switch (aggr_mode) {
+        case AGGR_CORE:
+                fprintf(output, "S%d-C%*d%s%*d%s",
+                        cpu_map__id_to_socket(id),
+                        csv_output ? 0 : -8,
+                        cpu_map__id_to_cpu(id),
+                        csv_sep,
+                        csv_output ? 0 : 4,
+                        nr,
+                        csv_sep);
+                break;
         case AGGR_SOCKET:
                 fprintf(output, "S%*d%s%*d%s",
                         csv_output ? 0 : -5,
-                        cpu,
+                        id,
                         csv_sep,
                         csv_output ? 0 : 4,
                         nr,
@@ -581,7 +596,7 @@ static void aggr_printout(struct perf_evsel *evsel, int cpu, int nr)
         case AGGR_NONE:
                 fprintf(output, "CPU%*d%s",
                         csv_output ? 0 : -4,
-                        perf_evsel__cpus(evsel)->map[cpu], csv_sep);
+                        perf_evsel__cpus(evsel)->map[id], csv_sep);
                 break;
         case AGGR_GLOBAL:
         default:
@@ -1095,6 +1110,7 @@ static void print_stat(int argc, const char **argv)
         }
 
         switch (aggr_mode) {
+        case AGGR_CORE:
         case AGGR_SOCKET:
                 print_aggr(NULL);
                 break;
@@ -1163,6 +1179,13 @@ static int perf_stat_init_aggr_mode(void)
                 }
                 aggr_get_id = cpu_map__get_socket;
                 break;
+        case AGGR_CORE:
+                if (cpu_map__build_core_map(evsel_list->cpus, &aggr_map)) {
+                        perror("cannot build core map");
+                        return -1;
+                }
+                aggr_get_id = cpu_map__get_core;
+                break;
         case AGGR_NONE:
         case AGGR_GLOBAL:
         default:
@@ -1372,6 +1395,8 @@ int cmd_stat(int argc, const char **argv, const char *prefix __maybe_unused)
                     "print counts at regular interval in ms (>= 100)"),
         OPT_SET_UINT(0, "per-socket", &aggr_mode,
                      "aggregate counts per processor socket", AGGR_SOCKET),
+        OPT_SET_UINT(0, "per-core", &aggr_mode,
+                     "aggregate counts per physical processor core", AGGR_CORE),
         OPT_END()
         };
         const char * const stat_usage[] = {
diff --git a/tools/perf/util/cpumap.c b/tools/perf/util/cpumap.c
index 7bb8e87a5847..beb8cf9f9976 100644
--- a/tools/perf/util/cpumap.c
+++ b/tools/perf/util/cpumap.c
@@ -267,7 +267,53 @@ static int cpu_map__build_map(struct cpu_map *cpus, struct cpu_map **res,
         return 0;
 }
 
+int cpu_map__get_core(struct cpu_map *map, int idx)
+{
+        FILE *fp;
+        const char *mnt;
+        char path[PATH_MAX];
+        int cpu, ret, s;
+
+        if (idx > map->nr)
+                return -1;
+
+        cpu = map->map[idx];
+
+        mnt = sysfs_find_mountpoint();
+        if (!mnt)
+                return -1;
+
+        snprintf(path, PATH_MAX,
+                "%s/devices/system/cpu/cpu%d/topology/core_id",
+                mnt, cpu);
+
+        fp = fopen(path, "r");
+        if (!fp)
+                return -1;
+        ret = fscanf(fp, "%d", &cpu);
+        fclose(fp);
+        if (ret != 1)
+                return -1;
+
+        s = cpu_map__get_socket(map, idx);
+        if (s == -1)
+                return -1;
+
+        /*
+         * encode socket in upper 16 bits
+         * core_id is relative to socket, and
+         * we need a global id. So we combine
+         * socket+ core id
+         */
+        return (s << 16) | (cpu & 0xffff);
+}
+
 int cpu_map__build_socket_map(struct cpu_map *cpus, struct cpu_map **sockp)
 {
         return cpu_map__build_map(cpus, sockp, cpu_map__get_socket);
 }
+
+int cpu_map__build_core_map(struct cpu_map *cpus, struct cpu_map **corep)
+{
+        return cpu_map__build_map(cpus, corep, cpu_map__get_core);
+}
diff --git a/tools/perf/util/cpumap.h b/tools/perf/util/cpumap.h
index 161b00756a12..9bed02e5fb3d 100644
--- a/tools/perf/util/cpumap.h
+++ b/tools/perf/util/cpumap.h
@@ -15,7 +15,9 @@ void cpu_map__delete(struct cpu_map *map);
 struct cpu_map *cpu_map__read(FILE *file);
 size_t cpu_map__fprintf(struct cpu_map *map, FILE *fp);
 int cpu_map__get_socket(struct cpu_map *map, int idx);
+int cpu_map__get_core(struct cpu_map *map, int idx);
 int cpu_map__build_socket_map(struct cpu_map *cpus, struct cpu_map **sockp);
+int cpu_map__build_core_map(struct cpu_map *cpus, struct cpu_map **corep);
 
 static inline int cpu_map__socket(struct cpu_map *sock, int s)
 {
@@ -24,6 +26,16 @@ static inline int cpu_map__socket(struct cpu_map *sock, int s)
         return sock->map[s];
 }
 
+static inline int cpu_map__id_to_socket(int id)
+{
+        return id >> 16;
+}
+
+static inline int cpu_map__id_to_cpu(int id)
+{
+        return id & 0xffff;
+}
+
 static inline int cpu_map__nr(const struct cpu_map *map)
 {
         return map ? map->nr : 1;