Commit 714647bd authored by Jiri Olsa's avatar Jiri Olsa Committed by Arnaldo Carvalho de Melo
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perf tools: Check maximum frequency rate for record/top 



Adding the check for maximum allowed frequency rate defined in following
file:

  /proc/sys/kernel/perf_event_max_sample_rate

When we cross the maximum value we fail and display detailed error
message with advise.

  $ perf record -F 3000 ls
  Maximum frequency rate (2000) reached.
  Please use -F freq option with lower value or consider
  tweaking /proc/sys/kernel/perf_event_max_sample_rate.

In case user does not specify the frequency and the default value cross
the maximum, we display warning and set the frequency value to the
current maximum.

  $ perf record ls
  Lowering default frequency rate to 2000.
  Please consider tweaking /proc/sys/kernel/perf_event_max_sample_rate.

Same messages are used for 'perf top'.

Signed-off-by: default avatarJiri Olsa <jolsa@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1383660887-1734-4-git-send-email-jolsa@redhat.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent a9862418

tools/perf/builtin-record.c

+1 −14
Original line number Diff line number Diff line
@@ -958,20 +958,7 @@ int cmd_record(int argc, const char **argv, const char *prefix __maybe_unused) 
	if (perf_evlist__create_maps(evsel_list, &rec->opts.target) < 0)

		usage_with_options(record_usage, record_options);



	if (rec->opts.user_interval != ULLONG_MAX)

		rec->opts.default_interval = rec->opts.user_interval;

	if (rec->opts.user_freq != UINT_MAX)

		rec->opts.freq = rec->opts.user_freq;



	/*

	 * User specified count overrides default frequency.

	 */

	if (rec->opts.default_interval)

		rec->opts.freq = 0;

	else if (rec->opts.freq) {

		rec->opts.default_interval = rec->opts.freq;

	} else {

		ui__error("frequency and count are zero, aborting\n");

	if (perf_record_opts__config(&rec->opts)) {

		err = -EINVAL;

		goto out_free_fd;

	}

tools/perf/builtin-top.c

+1 −14
Original line number Diff line number Diff line
@@ -1209,20 +1209,7 @@ int cmd_top(int argc, const char **argv, const char *prefix __maybe_unused) 
	if (top.delay_secs < 1)

		top.delay_secs = 1;



	if (opts->user_interval != ULLONG_MAX)

		opts->default_interval = opts->user_interval;

	if (opts->user_freq != UINT_MAX)

		opts->freq = opts->user_freq;



	/*

	 * User specified count overrides default frequency.

	 */

	if (opts->default_interval)

		opts->freq = 0;

	else if (opts->freq) {

		opts->default_interval = opts->freq;

	} else {

		ui__error("frequency and count are zero, aborting\n");

	if (perf_record_opts__config(opts)) {

		status = -EINVAL;

		goto out_delete_maps;

	}

tools/perf/util/evlist.h

+1 −0
Original line number Diff line number Diff line
@@ -99,6 +99,7 @@ void perf_evlist__set_id_pos(struct perf_evlist *evlist); 
bool perf_can_sample_identifier(void);

void perf_evlist__config(struct perf_evlist *evlist,

			 struct perf_record_opts *opts);

int perf_record_opts__config(struct perf_record_opts *opts);



int perf_evlist__prepare_workload(struct perf_evlist *evlist,

				  struct perf_target *target,

tools/perf/util/record.c

+71 −0
Original line number Diff line number Diff line
@@ -2,6 +2,8 @@ 
#include "evsel.h"

#include "cpumap.h"

#include "parse-events.h"

#include "fs.h"

#include "util.h"



typedef void (*setup_probe_fn_t)(struct perf_evsel *evsel);
@@ -106,3 +108,72 @@ void perf_evlist__config(struct perf_evlist *evlist, 


	perf_evlist__set_id_pos(evlist);

}



static int get_max_rate(unsigned int *rate)

{

	char path[PATH_MAX];

	const char *procfs = procfs__mountpoint();



	if (!procfs)

		return -1;



	snprintf(path, PATH_MAX,

		 "%s/sys/kernel/perf_event_max_sample_rate", procfs);



	return filename__read_int(path, (int *) rate);

}



static int perf_record_opts__config_freq(struct perf_record_opts *opts)

{

	bool user_freq = opts->user_freq != UINT_MAX;

	unsigned int max_rate;



	if (opts->user_interval != ULLONG_MAX)

		opts->default_interval = opts->user_interval;

	if (user_freq)

		opts->freq = opts->user_freq;



	/*

	 * User specified count overrides default frequency.

	 */

	if (opts->default_interval)

		opts->freq = 0;

	else if (opts->freq) {

		opts->default_interval = opts->freq;

	} else {

		pr_err("frequency and count are zero, aborting\n");

		return -1;

	}



	if (get_max_rate(&max_rate))

		return 0;



	/*

	 * User specified frequency is over current maximum.

	 */

	if (user_freq && (max_rate < opts->freq)) {

		pr_err("Maximum frequency rate (%u) reached.\n"

		   "Please use -F freq option with lower value or consider\n"

		   "tweaking /proc/sys/kernel/perf_event_max_sample_rate.\n",

		   max_rate);

		return -1;

	}



	/*

	 * Default frequency is over current maximum.

	 */

	if (max_rate < opts->freq) {

		pr_warning("Lowering default frequency rate to %u.\n"

			   "Please consider tweaking "

			   "/proc/sys/kernel/perf_event_max_sample_rate.\n",

			   max_rate);

		opts->freq = max_rate;

	}



	return 0;

}



int perf_record_opts__config(struct perf_record_opts *opts)

{

	return perf_record_opts__config_freq(opts);

}

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