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Date: Fri, 15 Feb 2013 17:28:49 -0500
From: Frederik Deweerdt <frederik.deweerdt@xprog.eu>
To: a.p.zijlstra@chello.nl, paulus@samba.org, mingo@redhat.com,
        acme@ghostprotocols.net
Cc: linux-kernel@vger.kernel.org
Subject: [patch] perf stat: --repeat forever
Message-ID: <20130215222849.GA5199@ks398093.ip-192-95-24.net>
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Hi,

The following patch causes 'perf stat --repeat 0' to be interpreted as
'forever', displaying the stats for every run.

We act as if a single run was asked, and reset the stats in each
iteration. In this mode SIGINT is passed to perf to be able to stop the
loop with Ctrl+C.

Regards,
Frederik


Signed-off-by: Frederik Deweerdt <frederik.deweerdt@gmail.com>

diff --git a/tools/perf/Documentation/perf-stat.txt b/tools/perf/Documentation/perf-stat.txt
index cf0c310..784976a 100644
--- a/tools/perf/Documentation/perf-stat.txt
+++ b/tools/perf/Documentation/perf-stat.txt
@@ -52,7 +52,7 @@ OPTIONS
 
 -r::
 --repeat=<n>::
-	repeat command and print average + stddev (max: 100)
+	repeat command and print average + stddev (max: 100). 0 means forever.
 
 -B::
 --big-num::
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index c247fac..b02b3a9 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -87,6 +87,7 @@ static FILE			*output				= NULL;
 static const char		*pre_cmd			= NULL;
 static const char		*post_cmd			= NULL;
 static bool			sync_run			= false;
+static bool			forever				= false;
 
 static volatile int done = 0;
 
@@ -94,6 +95,11 @@ struct perf_stat {
 	struct stats	  res_stats[3];
 };
 
+static void perf_evsel__reset_stat_priv(struct perf_evsel *evsel)
+{
+	memset(evsel->priv, 0, sizeof(struct perf_stat));
+}
+
 static int perf_evsel__alloc_stat_priv(struct perf_evsel *evsel)
 {
 	evsel->priv = zalloc(sizeof(struct perf_stat));
@@ -129,6 +135,22 @@ static struct stats runtime_itlb_cache_stats[MAX_NR_CPUS];
 static struct stats runtime_dtlb_cache_stats[MAX_NR_CPUS];
 static struct stats walltime_nsecs_stats;
 
+static void reset_stats(void)
+{
+	memset(runtime_nsecs_stats, 0, sizeof(runtime_nsecs_stats));
+	memset(runtime_cycles_stats, 0, sizeof(runtime_cycles_stats));
+	memset(runtime_stalled_cycles_front_stats, 0, sizeof(runtime_stalled_cycles_front_stats));
+	memset(runtime_stalled_cycles_back_stats, 0, sizeof(runtime_stalled_cycles_back_stats));
+	memset(runtime_branches_stats, 0, sizeof(runtime_branches_stats));
+	memset(runtime_cacherefs_stats, 0, sizeof(runtime_cacherefs_stats));
+	memset(runtime_l1_dcache_stats, 0, sizeof(runtime_l1_dcache_stats));
+	memset(runtime_l1_icache_stats, 0, sizeof(runtime_l1_icache_stats));
+	memset(runtime_ll_cache_stats, 0, sizeof(runtime_ll_cache_stats));
+	memset(runtime_itlb_cache_stats, 0, sizeof(runtime_itlb_cache_stats));
+	memset(runtime_dtlb_cache_stats, 0, sizeof(runtime_dtlb_cache_stats));
+	memset(&walltime_nsecs_stats, 0, sizeof(walltime_nsecs_stats));
+}
+
 static int create_perf_stat_counter(struct perf_evsel *evsel)
 {
 	struct perf_event_attr *attr = &evsel->attr;
@@ -1120,7 +1142,7 @@ int cmd_stat(int argc, const char **argv, const char *prefix __maybe_unused)
 	OPT_INCR('v', "verbose", &verbose,
 		    "be more verbose (show counter open errors, etc)"),
 	OPT_INTEGER('r', "repeat", &run_count,
-		    "repeat command and print average + stddev (max: 100)"),
+		    "repeat command and print average + stddev (max: 100, forever: 0)"),
 	OPT_BOOLEAN('n', "null", &null_run,
 		    "null run - dont start any counters"),
 	OPT_INCR('d', "detailed", &detailed_run,
@@ -1220,8 +1242,12 @@ int cmd_stat(int argc, const char **argv, const char *prefix __maybe_unused)
 
 	if (!argc && !perf_target__has_task(&target))
 		usage_with_options(stat_usage, options);
-	if (run_count <= 0)
+	if (run_count < 0) {
 		usage_with_options(stat_usage, options);
+	} else if (run_count == 0) {
+		forever = true;
+		run_count = 1;
+	}
 
 	/* no_aggr, cgroup are for system-wide only */
 	if ((no_aggr || nr_cgroups) && !perf_target__has_cpu(&target)) {
@@ -1259,21 +1285,31 @@ int cmd_stat(int argc, const char **argv, const char *prefix __maybe_unused)
 	 * task, but being ignored by perf stat itself:
 	 */
 	atexit(sig_atexit);
-	signal(SIGINT,  skip_signal);
+	if (!forever)
+		signal(SIGINT,  skip_signal);
 	signal(SIGALRM, skip_signal);
 	signal(SIGABRT, skip_signal);
 
 	status = 0;
-	for (run_idx = 0; run_idx < run_count; run_idx++) {
+	for (run_idx = 0; forever || run_idx < run_count; run_idx++) {
 		if (run_count != 1 && verbose)
 			fprintf(output, "[ perf stat: executing run #%d ... ]\n",
-				run_idx + 1);
+					run_idx + 1);
 
 		status = run_perf_stat(argc, argv);
+		if (forever && status != -1) {
+			print_stat(argc, argv);
+			list_for_each_entry(pos, &evsel_list->entries, node) {
+				perf_evsel__reset_stat_priv(pos);
+				perf_evsel__reset_counts(pos, perf_evsel__nr_cpus(pos));
+			}
+			reset_stats();
+		}
 	}
 
-	if (status != -1)
+	if (!forever && status != -1)
 		print_stat(argc, argv);
+
 out_free_fd:
 	list_for_each_entry(pos, &evsel_list->entries, node)
 		perf_evsel__free_stat_priv(pos);
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 1b16dd1..0c49e79 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -580,6 +580,12 @@ int perf_evsel__alloc_id(struct perf_evsel *evsel, int ncpus, int nthreads)
 	return 0;
 }
 
+void perf_evsel__reset_counts(struct perf_evsel *evsel, int ncpus)
+{
+	memset(evsel->counts, 0, (sizeof(*evsel->counts) +
+				 (ncpus * sizeof(struct perf_counts_values))));
+}
+
 int perf_evsel__alloc_counts(struct perf_evsel *evsel, int ncpus)
 {
 	evsel->counts = zalloc((sizeof(*evsel->counts) +
diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index 3d2b801..364d820 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -114,6 +114,7 @@ const char *perf_evsel__name(struct perf_evsel *evsel);
 int perf_evsel__alloc_fd(struct perf_evsel *evsel, int ncpus, int nthreads);
 int perf_evsel__alloc_id(struct perf_evsel *evsel, int ncpus, int nthreads);
 int perf_evsel__alloc_counts(struct perf_evsel *evsel, int ncpus);
+void perf_evsel__reset_counts(struct perf_evsel *evsel, int ncpus);
 void perf_evsel__free_fd(struct perf_evsel *evsel);
 void perf_evsel__free_id(struct perf_evsel *evsel);
 void perf_evsel__close_fd(struct perf_evsel *evsel, int ncpus, int nthreads);