perf stat: Add support to measure SMI cost

Implementing a new --smi-cost mode in perf stat to measure SMI cost.

During the measurement, the /sys/device/cpu/freeze_on_smi will be set.

The measurement can be done with one counter (unhalted core cycles), and
two free running MSR counters (IA32_APERF and SMI_COUNT).

In practice, the percentages of SMI core cycles should be more useful
than absolute value. So the output will be the percentage of SMI core
cycles and SMI#. metric_only will be set by default.

SMI cycles% = (aperf - unhalted core cycles) / aperf

Here is an example output.

 Performance counter stats for 'sudo echo ':

SMI cycles%          SMI#
    0.1%              1

       0.010858678 seconds time elapsed

Users who wants to get the actual value can apply additional
--no-metric-only.

Signed-off-by: Kan Liang <Kan.liang@intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Robert Elliott <elliott@hpe.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1495825538-5230-3-git-send-email-kan.liang@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 33 insertions, 0 deletions

diff --git a/tools/perf/util/stat-shadow.c b/tools/perf/util/stat-shadow.c
index ac10cc675d39..719d6cb86952 100644
--- a/tools/perf/util/stat-shadow.c
+++ b/tools/perf/util/stat-shadow.c
@@ -44,6 +44,8 @@ static struct stats runtime_topdown_slots_issued[NUM_CTX][MAX_NR_CPUS];
 static struct stats runtime_topdown_slots_retired[NUM_CTX][MAX_NR_CPUS];
 static struct stats runtime_topdown_fetch_bubbles[NUM_CTX][MAX_NR_CPUS];
 static struct stats runtime_topdown_recovery_bubbles[NUM_CTX][MAX_NR_CPUS];
+static struct stats runtime_smi_num_stats[NUM_CTX][MAX_NR_CPUS];
+static struct stats runtime_aperf_stats[NUM_CTX][MAX_NR_CPUS];
 static struct rblist runtime_saved_values;
 static bool have_frontend_stalled;
 
@@ -157,6 +159,8 @@ void perf_stat__reset_shadow_stats(void)
         memset(runtime_topdown_slots_issued, 0, sizeof(runtime_topdown_slots_issued));
         memset(runtime_topdown_fetch_bubbles, 0, sizeof(runtime_topdown_fetch_bubbles));
         memset(runtime_topdown_recovery_bubbles, 0, sizeof(runtime_topdown_recovery_bubbles));
+        memset(runtime_smi_num_stats, 0, sizeof(runtime_smi_num_stats));
+        memset(runtime_aperf_stats, 0, sizeof(runtime_aperf_stats));
 
         next = rb_first(&runtime_saved_values.entries);
         while (next) {
@@ -217,6 +221,10 @@ void perf_stat__update_shadow_stats(struct perf_evsel *counter, u64 *count,
                 update_stats(&runtime_dtlb_cache_stats[ctx][cpu], count[0]);
         else if (perf_evsel__match(counter, HW_CACHE, HW_CACHE_ITLB))
                 update_stats(&runtime_itlb_cache_stats[ctx][cpu], count[0]);
+        else if (perf_stat_evsel__is(counter, SMI_NUM))
+                update_stats(&runtime_smi_num_stats[ctx][cpu], count[0]);
+        else if (perf_stat_evsel__is(counter, APERF))
+                update_stats(&runtime_aperf_stats[ctx][cpu], count[0]);
 
         if (counter->collect_stat) {
                 struct saved_value *v = saved_value_lookup(counter, cpu, ctx,
@@ -592,6 +600,29 @@ static double td_be_bound(int ctx, int cpu)
         return sanitize_val(1.0 - sum);
 }
 
+static void print_smi_cost(int cpu, struct perf_evsel *evsel,
+                           struct perf_stat_output_ctx *out)
+{
+        double smi_num, aperf, cycles, cost = 0.0;
+        int ctx = evsel_context(evsel);
+        const char *color = NULL;
+
+        smi_num = avg_stats(&runtime_smi_num_stats[ctx][cpu]);
+        aperf = avg_stats(&runtime_aperf_stats[ctx][cpu]);
+        cycles = avg_stats(&runtime_cycles_stats[ctx][cpu]);
+
+        if ((cycles == 0) || (aperf == 0))
+                return;
+
+        if (smi_num)
+                cost = (aperf - cycles) / aperf * 100.00;
+
+        if (cost > 10)
+                color = PERF_COLOR_RED;
+        out->print_metric(out->ctx, color, "%8.1f%%", "SMI cycles%", cost);
+        out->print_metric(out->ctx, NULL, "%4.0f", "SMI#", smi_num);
+}
+
 void perf_stat__print_shadow_stats(struct perf_evsel *evsel,
                                    double avg, int cpu,
                                    struct perf_stat_output_ctx *out)
@@ -825,6 +856,8 @@ void perf_stat__print_shadow_stats(struct perf_evsel *evsel,
                 }
                 snprintf(unit_buf, sizeof(unit_buf), "%c/sec", unit);
                 print_metric(ctxp, NULL, "%8.3f", unit_buf, ratio);
+        } else if (perf_stat_evsel__is(evsel, SMI_NUM)) {
+                print_smi_cost(cpu, evsel, out);
         } else {
                 print_metric(ctxp, NULL, NULL, NULL, 0);
         }