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perf stat: Add support to measure SMI cost

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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>
This commit is contained in:
Kan Liang
2017-05-26 12:05:38 -07:00
committed by Arnaldo Carvalho de Melo
parent 3b00ea9386
commit daefd0bc0b
5 changed files with 100 additions and 0 deletions
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33
tools/perf/util/stat-shadow.c
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@@ -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);
}