perf stat: Check for frontend stalled for metrics

Add an extra check for frontend stalled in the metrics.  This avoids an
extra column for the --metric-only case when the CPU does not support
frontend stalled.

v2: Add separate init function

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: http://lkml.kernel.org/r/1456858672-21594-8-git-send-email-andi@firstfloor.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

3 files changed, 10 insertions, 1 deletions

diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 9b5089c5dffe..baa82078c148 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -1966,6 +1966,7 @@ int cmd_stat(int argc, const char **argv, const char *prefix __maybe_unused)
         argc = parse_options_subcommand(argc, argv, stat_options, stat_subcommands,
                                         (const char **) stat_usage,
                                         PARSE_OPT_STOP_AT_NON_OPTION);
+        perf_stat__init_shadow_stats();
 
         if (csv_sep) {
                 csv_output = true;
diff --git a/tools/perf/util/stat-shadow.c b/tools/perf/util/stat-shadow.c
index 5e2d2e34e1bc..b33ffb2af2cf 100644
--- a/tools/perf/util/stat-shadow.c
+++ b/tools/perf/util/stat-shadow.c
@@ -2,6 +2,7 @@
 #include "evsel.h"
 #include "stat.h"
 #include "color.h"
+#include "pmu.h"
 
 enum {
         CTX_BIT_USER    = 1 << 0,
@@ -35,9 +36,15 @@ static struct stats runtime_dtlb_cache_stats[NUM_CTX][MAX_NR_CPUS];
 static struct stats runtime_cycles_in_tx_stats[NUM_CTX][MAX_NR_CPUS];
 static struct stats runtime_transaction_stats[NUM_CTX][MAX_NR_CPUS];
 static struct stats runtime_elision_stats[NUM_CTX][MAX_NR_CPUS];
+static bool have_frontend_stalled;
 
 struct stats walltime_nsecs_stats;
 
+void perf_stat__init_shadow_stats(void)
+{
+        have_frontend_stalled = pmu_have_event("cpu", "stalled-cycles-frontend");
+}
+
 static int evsel_context(struct perf_evsel *evsel)
 {
         int ctx = 0;
@@ -323,7 +330,7 @@ void perf_stat__print_shadow_stats(struct perf_evsel *evsel,
                         print_metric(ctxp, NULL, "%7.2f ",
                                         "stalled cycles per insn",
                                         ratio);
-                } else {
+                } else if (have_frontend_stalled) {
                         print_metric(ctxp, NULL, NULL,
                                      "stalled cycles per insn", 0);
                 }
diff --git a/tools/perf/util/stat.h b/tools/perf/util/stat.h
index f02af68adc04..0150e786ccc7 100644
--- a/tools/perf/util/stat.h
+++ b/tools/perf/util/stat.h
@@ -72,6 +72,7 @@ typedef void (*print_metric_t)(void *ctx, const char *color, const char *unit,
                                const char *fmt, double val);
 typedef void (*new_line_t )(void *ctx);
 
+void perf_stat__init_shadow_stats(void);
 void perf_stat__reset_shadow_stats(void);
 void perf_stat__update_shadow_stats(struct perf_evsel *counter, u64 *count,
                                     int cpu);