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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: Frederic 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>
This commit is contained in:
Frederic Weisbecker 2010-04-14 22:09:02 +02:00
parent bdef3b02ce
commit f921281930
2 changed files with 24 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

36
tools/perf/builtin-record.c
View File

@ -33,11 +33,13 @@ enum write_mode_t {
static int *fd[MAX_NR_CPUS][MAX_COUNTERS];
static unsigned int user_interval = UINT_MAX;
static long default_interval = 0;
static int nr_cpus = 0;
static unsigned int page_size;
static unsigned int mmap_pages = 128;
static unsigned int user_freq = UINT_MAX;
static int freq = 1000;
static int output;
static const char *output_name = "perf.data";
@ -255,10 +257,19 @@ static void create_counter(int counter, int cpu)
if (nr_counters > 1)
attr->sample_type |= PERF_SAMPLE_ID;
if (freq) {
attr->sample_type |= PERF_SAMPLE_PERIOD;
attr->freq = 1;
attr->sample_freq = freq;
/*
* We default some events to a 1 default interval. But keep
* it a weak assumption overridable by the user.
*/
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)
@ -689,13 +700,13 @@ static const struct option options[] = {
"CPU to profile on"),
OPT_BOOLEAN('f', "force", &force,
"overwrite existing data file (deprecated)"),
OPT_LONG('c', "count", &default_interval,
OPT_LONG('c', "count", &user_interval,
"event period to sample"),
OPT_STRING('o', "output", &output_name, "file",
"output file name"),
OPT_BOOLEAN('i', "inherit", &inherit,
"child tasks inherit counters"),
OPT_INTEGER('F', "freq", &freq,
OPT_INTEGER('F', "freq", &user_freq,
"profile at this frequency"),
OPT_INTEGER('m', "mmap-pages", &mmap_pages,
"number of mmap data pages"),
@ -716,7 +727,6 @@ static const struct option options[] = {
int cmd_record(int argc, const char **argv, const char *prefix __used)
{
int counter;
int i,j;
argc = parse_options(argc, argv, options, record_usage,
@ -774,6 +784,11 @@ int cmd_record(int argc, const char **argv, const char *prefix __used)
if (!event_array)
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.
*/
@ -786,12 +801,5 @@ int cmd_record(int argc, const char **argv, const char *prefix __used)
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);
}

2
tools/perf/util/parse-events.c
View File

@ -422,6 +422,8 @@ parse_single_tracepoint_event(char *sys_name,
attr->sample_type |= PERF_SAMPLE_TIME;
attr->sample_type |= PERF_SAMPLE_CPU;
attr->sample_period = 1;
snprintf(evt_path, MAXPATHLEN, "%s/%s/%s/id", debugfs_path,
sys_name, evt_name);