perf tools: Per-event time support

This patchkit adds the ability to turn off time stamps per event.

One usaful case for partial time is to work with per-event callgraph to
enable "PEBS threshold > 1" (https://lkml.org/lkml/2015/5/10/196), which
can significantly reduce the sampling overhead.

The event samples with time stamps off will not be ordered.

Signed-off-by: Kan Liang <kan.liang@intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/1438677022-34296-2-git-send-email-kan.liang@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Documentation/perf-record.txt

@@ -49,7 +49,9 @@ OPTIONS
 	  These params can be used to overload default config values per event.
 	  Here is a list of the params.
 	  - 'period': Set event sampling period
-
+	  - 'time': Disable/enable time stamping. Acceptable values are 1 for
+		    enabling time stamping. 0 for disabling time stamping.
+		    The default is 1.
 	  Note: If user explicitly sets options which conflict with the params,
 	  the value set by the params will be overridden.
 

tools/perf/util/evsel.c

@@ -587,15 +587,23 @@ perf_evsel__config_callgraph(struct perf_evsel *evsel,
 	}
 }
 
-static void apply_config_terms(struct perf_event_attr *attr __maybe_unused,
-			       struct list_head *config_terms)
+static void apply_config_terms(struct perf_evsel *evsel)
 {
 	struct perf_evsel_config_term *term;
+	struct list_head *config_terms = &evsel->config_terms;
+	struct perf_event_attr *attr = &evsel->attr;
 
 	list_for_each_entry(term, config_terms, list) {
 		switch (term->type) {
 		case PERF_EVSEL__CONFIG_TERM_PERIOD:
 			attr->sample_period = term->val.period;
+			break;
+		case PERF_EVSEL__CONFIG_TERM_TIME:
+			if (term->val.time)
+				perf_evsel__set_sample_bit(evsel, TIME);
+			else
+				perf_evsel__reset_sample_bit(evsel, TIME);
+			break;
 		default:
 			break;
 		}
@@ -798,7 +806,7 @@ void perf_evsel__config(struct perf_evsel *evsel, struct record_opts *opts)
 	 * Apply event specific term settings,
 	 * it overloads any global configuration.
 	 */
-	apply_config_terms(attr, &evsel->config_terms);
+	apply_config_terms(evsel);
 }
 
 static int perf_evsel__alloc_fd(struct perf_evsel *evsel, int ncpus, int nthreads)

tools/perf/util/evsel.h

@@ -39,6 +39,7 @@ struct cgroup_sel;
 */
 enum {
 	PERF_EVSEL__CONFIG_TERM_PERIOD,
+	PERF_EVSEL__CONFIG_TERM_TIME,
 	PERF_EVSEL__CONFIG_TERM_MAX,
 };
 
@@ -47,6 +48,7 @@ struct perf_evsel_config_term {
 	int	type;
 	union {
 		u64	period;
+		bool	time;
 	} val;
 };
 

tools/perf/util/parse-events.c

@@ -603,6 +603,14 @@ do {									   \
 		 * attr->branch_sample_type = term->val.num;
 		 */
 		break;
+	case PARSE_EVENTS__TERM_TYPE_TIME:
+		CHECK_TYPE_VAL(NUM);
+		if (term->val.num > 1) {
+			err->str = strdup("expected 0 or 1");
+			err->idx = term->err_val;
+			return -EINVAL;
+		}
+		break;
 	case PARSE_EVENTS__TERM_TYPE_NAME:
 		CHECK_TYPE_VAL(STR);
 		break;
@@ -650,6 +658,10 @@ do {								\
 		switch (term->type_term) {
 		case PARSE_EVENTS__TERM_TYPE_SAMPLE_PERIOD:
 			ADD_CONFIG_TERM(PERIOD, period, term->val.num);
+			break;
+		case PARSE_EVENTS__TERM_TYPE_TIME:
+			ADD_CONFIG_TERM(TIME, time, term->val.num);
+			break;
 		default:
 			break;
 		}

tools/perf/util/parse-events.h

@@ -63,6 +63,7 @@ enum {
 	PARSE_EVENTS__TERM_TYPE_NAME,
 	PARSE_EVENTS__TERM_TYPE_SAMPLE_PERIOD,
 	PARSE_EVENTS__TERM_TYPE_BRANCH_SAMPLE_TYPE,
+	PARSE_EVENTS__TERM_TYPE_TIME,
 };
 
 struct parse_events_term {

tools/perf/util/parse-events.l

@@ -183,6 +183,7 @@ config2			{ return term(yyscanner, PARSE_EVENTS__TERM_TYPE_CONFIG2); }
 name			{ return term(yyscanner, PARSE_EVENTS__TERM_TYPE_NAME); }
 period			{ return term(yyscanner, PARSE_EVENTS__TERM_TYPE_SAMPLE_PERIOD); }
 branch_type		{ return term(yyscanner, PARSE_EVENTS__TERM_TYPE_BRANCH_SAMPLE_TYPE); }
+time			{ return term(yyscanner, PARSE_EVENTS__TERM_TYPE_TIME); }
 ,			{ return ','; }
 "/"			{ BEGIN(INITIAL); return '/'; }
 {name_minus}		{ return str(yyscanner, PE_NAME); }

tools/perf/util/pmu.c

@@ -607,7 +607,7 @@ static char *formats_error_string(struct list_head *formats)
 {
 	struct perf_pmu_format *format;
 	char *err, *str;
-	static const char *static_terms = "config,config1,config2,name,period,branch_type\n";
+	static const char *static_terms = "config,config1,config2,name,period,branch_type,time\n";
 	unsigned i = 0;
 
 	if (!asprintf(&str, "valid terms:"))