From 67230479b2304be99e9451ee171aa288a112ea16 Mon Sep 17 00:00:00 2001 From: Arnaldo Carvalho de Melo Date: Thu, 1 Mar 2018 13:46:23 -0300 Subject: [PATCH] perf record: Allow asking for the maximum allowed sample rate Add the handy '-F max' shortcut to reading and using the kernel.perf_event_max_sample_rate value as the user supplied sampling frequency: # perf record -F max sleep 1 info: Using a maximum frequency rate of 15,000 Hz [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.019 MB perf.data (14 samples) ] # sysctl kernel.perf_event_max_sample_rate kernel.perf_event_max_sample_rate = 15000 # perf evlist -v cycles:ppp: size: 112, { sample_period, sample_freq }: 15000, sample_type: IP|TID|TIME|PERIOD, disabled: 1, inherit: 1, mmap: 1, comm: 1, freq: 1, enable_on_exec: 1, task: 1, precise_ip: 3, sample_id_all: 1, exclude_guest: 1, mmap2: 1, comm_exec: 1 # perf record -F 10 sleep 1 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.019 MB perf.data (4 samples) ] # perf evlist -v cycles:ppp: size: 112, { sample_period, sample_freq }: 10, sample_type: IP|TID|TIME|PERIOD, disabled: 1, inherit: 1, mmap: 1, comm: 1, freq: 1, enable_on_exec: 1, task: 1, precise_ip: 3, sample_id_all: 1, exclude_guest: 1, mmap2: 1, comm_exec: 1 # Suggested-by: Ingo Molnar Cc: Adrian Hunter Cc: David Ahern Cc: Jiri Olsa Cc: Namhyung Kim Cc: Wang Nan Link: https://lkml.kernel.org/n/tip-4y0tiuws62c64gp4cf0hme0m@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/Documentation/perf-record.txt | 4 +++- tools/perf/builtin-record.c | 7 ++++++- tools/perf/perf.h | 2 ++ tools/perf/util/record.c | 23 +++++++++++++++++++++++ 4 files changed, 34 insertions(+), 2 deletions(-) diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt index 76bc218..94f2fae 100644 --- a/tools/perf/Documentation/perf-record.txt +++ b/tools/perf/Documentation/perf-record.txt @@ -193,7 +193,9 @@ OPTIONS Child tasks do not inherit counters. -F:: --freq=:: - Profile at this frequency. + Profile at this frequency. Use 'max' to use the currently maximum + allowed frequency, i.e. the value in the kernel.perf_event_max_sample_rate + sysctl. -m:: --mmap-pages=:: diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c index 9072672..e1821ee 100644 --- a/tools/perf/builtin-record.c +++ b/tools/perf/builtin-record.c @@ -45,6 +45,7 @@ #include #include +#include #include #include #include @@ -1542,7 +1543,9 @@ static struct option __record_options[] = { OPT_BOOLEAN(0, "tail-synthesize", &record.opts.tail_synthesize, "synthesize non-sample events at the end of output"), OPT_BOOLEAN(0, "overwrite", &record.opts.overwrite, "use overwrite mode"), - OPT_UINTEGER('F', "freq", &record.opts.user_freq, "profile at this frequency"), + OPT_CALLBACK('F', "freq", &record.opts, "freq or 'max'", + "profile at this frequency", + record__parse_freq), OPT_CALLBACK('m', "mmap-pages", &record.opts, "pages[,pages]", "number of mmap data pages and AUX area tracing mmap pages", record__parse_mmap_pages), @@ -1651,6 +1654,8 @@ int cmd_record(int argc, const char **argv) struct record *rec = &record; char errbuf[BUFSIZ]; + setlocale(LC_ALL, ""); + #ifndef HAVE_LIBBPF_SUPPORT # define set_nobuild(s, l, c) set_option_nobuild(record_options, s, l, "NO_LIBBPF=1", c) set_nobuild('\0', "clang-path", true); diff --git a/tools/perf/perf.h b/tools/perf/perf.h index cfe4623..a5df8bf 100644 --- a/tools/perf/perf.h +++ b/tools/perf/perf.h @@ -82,4 +82,6 @@ struct record_opts { struct option; extern const char * const *record_usage; extern struct option *record_options; + +int record__parse_freq(const struct option *opt, const char *str, int unset); #endif diff --git a/tools/perf/util/record.c b/tools/perf/util/record.c index 1e97937..acabf54 100644 --- a/tools/perf/util/record.c +++ b/tools/perf/util/record.c @@ -5,6 +5,7 @@ #include "parse-events.h" #include #include +#include #include "util.h" #include "cloexec.h" @@ -287,3 +288,25 @@ out_delete: perf_evlist__delete(temp_evlist); return ret; } + +int record__parse_freq(const struct option *opt, const char *str, int unset __maybe_unused) +{ + unsigned int freq; + struct record_opts *opts = opt->value; + + if (!str) + return -EINVAL; + + if (strcasecmp(str, "max") == 0) { + if (get_max_rate(&freq)) { + pr_err("couldn't read /proc/sys/kernel/perf_event_max_sample_rate\n"); + return -1; + } + pr_info("info: Using a maximum frequency rate of %'d Hz\n", freq); + } else { + freq = atoi(str); + } + + opts->user_freq = freq; + return 0; +} -- 2.7.4