perf record, top: Implement --freq

Support frequency-based profiling and make it the default.

(Also add a Hz printout in perf top.)

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Documentation/perf_counter/builtin-record.c

@@ -27,6 +27,7 @@ static int			fd[MAX_NR_CPUS][MAX_COUNTERS];
 static int			nr_cpus				= 0;
 static unsigned int		page_size;
 static unsigned int		mmap_pages			= 128;
+static int			freq				= 0;
 static int			output;
 static const char		*output_name			= "perf.data";
 static int			group				= 0;
@@ -347,6 +348,7 @@ static void create_counter(int counter, int cpu, pid_t pid)
 	attr.config		= event_id[counter];
 	attr.sample_period	= event_count[counter];
 	attr.sample_type	= PERF_SAMPLE_IP | PERF_SAMPLE_TID;
+	attr.freq		= freq;
 	attr.mmap		= track;
 	attr.comm		= track;
 	attr.inherit		= (cpu < 0) && inherit;
@@ -520,6 +522,8 @@ static const struct option options[] = {
 		    "output file name"),
 	OPT_BOOLEAN('i', "inherit", &inherit,
 		    "child tasks inherit counters"),
+	OPT_INTEGER('F', "freq", &freq,
+		    "profile at this frequency"),
 	OPT_INTEGER('m', "mmap-pages", &mmap_pages,
 		    "number of mmap data pages"),
 	OPT_END()
@@ -540,6 +544,10 @@ int cmd_record(int argc, const char **argv, const char *prefix)
 		event_id[0] = 0;
 	}
 
+	if (freq) {
+		default_interval = freq;
+		freq = 1;
+	}
 	for (counter = 0; counter < nr_counters; counter++) {
 		if (event_count[counter])
 			continue;

Documentation/perf_counter/builtin-top.c

@@ -212,8 +212,13 @@ static void print_sym_table(void)
 		events_per_sec,
 		100.0 - (100.0*((events_per_sec-kevents_per_sec)/events_per_sec)));
 
-	if (nr_counters == 1)
-		printf("%d ", event_count[0]);
+	if (nr_counters == 1) {
+		printf("%d", event_count[0]);
+		if (freq)
+			printf("Hz ");
+		else
+			printf(" ");
+	}
 
 	for (counter = 0; counter < nr_counters; counter++) {
 		if (counter)