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: Jiri 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: Arnaldo Carvalho de Melo <acme@redhat.com>
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@ -958,20 +958,7 @@ int cmd_record(int argc, const char **argv, const char *prefix __maybe_unused)
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if (perf_evlist__create_maps(evsel_list, &rec->opts.target) < 0)
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usage_with_options(record_usage, record_options);
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if (rec->opts.user_interval != ULLONG_MAX)
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rec->opts.default_interval = rec->opts.user_interval;
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if (rec->opts.user_freq != UINT_MAX)
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rec->opts.freq = rec->opts.user_freq;
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/*
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* User specified count overrides default frequency.
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*/
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if (rec->opts.default_interval)
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rec->opts.freq = 0;
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else if (rec->opts.freq) {
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rec->opts.default_interval = rec->opts.freq;
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} else {
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ui__error("frequency and count are zero, aborting\n");
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if (perf_record_opts__config(&rec->opts)) {
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err = -EINVAL;
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goto out_free_fd;
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}
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@ -1209,20 +1209,7 @@ int cmd_top(int argc, const char **argv, const char *prefix __maybe_unused)
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if (top.delay_secs < 1)
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top.delay_secs = 1;
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if (opts->user_interval != ULLONG_MAX)
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opts->default_interval = opts->user_interval;
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if (opts->user_freq != UINT_MAX)
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opts->freq = opts->user_freq;
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/*
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* User specified count overrides default frequency.
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*/
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if (opts->default_interval)
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opts->freq = 0;
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else if (opts->freq) {
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opts->default_interval = opts->freq;
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} else {
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ui__error("frequency and count are zero, aborting\n");
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if (perf_record_opts__config(opts)) {
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status = -EINVAL;
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goto out_delete_maps;
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}
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@ -99,6 +99,7 @@ void perf_evlist__set_id_pos(struct perf_evlist *evlist);
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bool perf_can_sample_identifier(void);
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void perf_evlist__config(struct perf_evlist *evlist,
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struct perf_record_opts *opts);
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int perf_record_opts__config(struct perf_record_opts *opts);
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int perf_evlist__prepare_workload(struct perf_evlist *evlist,
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struct perf_target *target,
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@ -2,6 +2,8 @@
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#include "evsel.h"
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#include "cpumap.h"
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#include "parse-events.h"
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#include "fs.h"
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#include "util.h"
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typedef void (*setup_probe_fn_t)(struct perf_evsel *evsel);
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@ -106,3 +108,72 @@ void perf_evlist__config(struct perf_evlist *evlist,
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perf_evlist__set_id_pos(evlist);
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}
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static int get_max_rate(unsigned int *rate)
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{
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char path[PATH_MAX];
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const char *procfs = procfs__mountpoint();
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if (!procfs)
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return -1;
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snprintf(path, PATH_MAX,
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"%s/sys/kernel/perf_event_max_sample_rate", procfs);
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return filename__read_int(path, (int *) rate);
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}
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static int perf_record_opts__config_freq(struct perf_record_opts *opts)
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{
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bool user_freq = opts->user_freq != UINT_MAX;
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unsigned int max_rate;
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if (opts->user_interval != ULLONG_MAX)
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opts->default_interval = opts->user_interval;
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if (user_freq)
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opts->freq = opts->user_freq;
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/*
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* User specified count overrides default frequency.
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*/
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if (opts->default_interval)
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opts->freq = 0;
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else if (opts->freq) {
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opts->default_interval = opts->freq;
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} else {
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pr_err("frequency and count are zero, aborting\n");
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return -1;
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}
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if (get_max_rate(&max_rate))
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return 0;
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/*
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* User specified frequency is over current maximum.
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*/
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if (user_freq && (max_rate < opts->freq)) {
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pr_err("Maximum frequency rate (%u) reached.\n"
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"Please use -F freq option with lower value or consider\n"
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"tweaking /proc/sys/kernel/perf_event_max_sample_rate.\n",
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max_rate);
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return -1;
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}
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/*
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* Default frequency is over current maximum.
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*/
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if (max_rate < opts->freq) {
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pr_warning("Lowering default frequency rate to %u.\n"
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"Please consider tweaking "
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"/proc/sys/kernel/perf_event_max_sample_rate.\n",
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max_rate);
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opts->freq = max_rate;
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}
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return 0;
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}
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int perf_record_opts__config(struct perf_record_opts *opts)
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{
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return perf_record_opts__config_freq(opts);
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}
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