Commit f9212819 authored by Frederic Weisbecker's avatar Frederic Weisbecker

perf: Make the trace events sample period default to 1

Trace events are mostly used for tracing and then require not to
be lost when possible. As opposite to hardware events that really
require to trigger after a given sample period, trace events mostly
need to trigger everytime.

It is a frustrating experience to trace with perf and realize we
lost a lot of events because we forgot the "-c 1" option.

Then default sample_period to 1 for trace events but let the user
override it.
Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
parent bdef3b02
...@@ -33,11 +33,13 @@ enum write_mode_t { ...@@ -33,11 +33,13 @@ enum write_mode_t {
static int *fd[MAX_NR_CPUS][MAX_COUNTERS]; static int *fd[MAX_NR_CPUS][MAX_COUNTERS];
static unsigned int user_interval = UINT_MAX;
static long default_interval = 0; static long default_interval = 0;
static int nr_cpus = 0; static int nr_cpus = 0;
static unsigned int page_size; static unsigned int page_size;
static unsigned int mmap_pages = 128; static unsigned int mmap_pages = 128;
static unsigned int user_freq = UINT_MAX;
static int freq = 1000; static int freq = 1000;
static int output; static int output;
static const char *output_name = "perf.data"; static const char *output_name = "perf.data";
...@@ -255,10 +257,19 @@ static void create_counter(int counter, int cpu) ...@@ -255,10 +257,19 @@ static void create_counter(int counter, int cpu)
if (nr_counters > 1) if (nr_counters > 1)
attr->sample_type |= PERF_SAMPLE_ID; attr->sample_type |= PERF_SAMPLE_ID;
if (freq) { /*
attr->sample_type |= PERF_SAMPLE_PERIOD; * We default some events to a 1 default interval. But keep
attr->freq = 1; * it a weak assumption overridable by the user.
attr->sample_freq = freq; */
if (!attr->sample_period || (user_freq != UINT_MAX &&
user_interval != UINT_MAX)) {
if (freq) {
attr->sample_type |= PERF_SAMPLE_PERIOD;
attr->freq = 1;
attr->sample_freq = freq;
} else {
attr->sample_period = default_interval;
}
} }
if (no_samples) if (no_samples)
...@@ -689,13 +700,13 @@ static const struct option options[] = { ...@@ -689,13 +700,13 @@ static const struct option options[] = {
"CPU to profile on"), "CPU to profile on"),
OPT_BOOLEAN('f', "force", &force, OPT_BOOLEAN('f', "force", &force,
"overwrite existing data file (deprecated)"), "overwrite existing data file (deprecated)"),
OPT_LONG('c', "count", &default_interval, OPT_LONG('c', "count", &user_interval,
"event period to sample"), "event period to sample"),
OPT_STRING('o', "output", &output_name, "file", OPT_STRING('o', "output", &output_name, "file",
"output file name"), "output file name"),
OPT_BOOLEAN('i', "inherit", &inherit, OPT_BOOLEAN('i', "inherit", &inherit,
"child tasks inherit counters"), "child tasks inherit counters"),
OPT_INTEGER('F', "freq", &freq, OPT_INTEGER('F', "freq", &user_freq,
"profile at this frequency"), "profile at this frequency"),
OPT_INTEGER('m', "mmap-pages", &mmap_pages, OPT_INTEGER('m', "mmap-pages", &mmap_pages,
"number of mmap data pages"), "number of mmap data pages"),
...@@ -716,7 +727,6 @@ static const struct option options[] = { ...@@ -716,7 +727,6 @@ static const struct option options[] = {
int cmd_record(int argc, const char **argv, const char *prefix __used) int cmd_record(int argc, const char **argv, const char *prefix __used)
{ {
int counter;
int i,j; int i,j;
argc = parse_options(argc, argv, options, record_usage, argc = parse_options(argc, argv, options, record_usage,
...@@ -774,6 +784,11 @@ int cmd_record(int argc, const char **argv, const char *prefix __used) ...@@ -774,6 +784,11 @@ int cmd_record(int argc, const char **argv, const char *prefix __used)
if (!event_array) if (!event_array)
return -ENOMEM; return -ENOMEM;
if (user_interval != UINT_MAX)
default_interval = user_interval;
if (user_freq != UINT_MAX)
freq = user_freq;
/* /*
* User specified count overrides default frequency. * User specified count overrides default frequency.
*/ */
...@@ -786,12 +801,5 @@ int cmd_record(int argc, const char **argv, const char *prefix __used) ...@@ -786,12 +801,5 @@ int cmd_record(int argc, const char **argv, const char *prefix __used)
exit(EXIT_FAILURE); exit(EXIT_FAILURE);
} }
for (counter = 0; counter < nr_counters; counter++) {
if (attrs[counter].sample_period)
continue;
attrs[counter].sample_period = default_interval;
}
return __cmd_record(argc, argv); return __cmd_record(argc, argv);
} }
...@@ -422,6 +422,8 @@ parse_single_tracepoint_event(char *sys_name, ...@@ -422,6 +422,8 @@ parse_single_tracepoint_event(char *sys_name,
attr->sample_type |= PERF_SAMPLE_TIME; attr->sample_type |= PERF_SAMPLE_TIME;
attr->sample_type |= PERF_SAMPLE_CPU; attr->sample_type |= PERF_SAMPLE_CPU;
attr->sample_period = 1;
snprintf(evt_path, MAXPATHLEN, "%s/%s/%s/id", debugfs_path, snprintf(evt_path, MAXPATHLEN, "%s/%s/%s/id", debugfs_path,
sys_name, evt_name); sys_name, evt_name);
......
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