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author | Arnaldo Carvalho de Melo <acme@redhat.com> | 2018-03-01 13:46:23 -0300 |
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committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2018-03-05 09:58:43 -0300 |
commit | 67230479b2304be99e9451ee171aa288a112ea16 (patch) | |
tree | ef8566f22145f433806f62fc7eaf7817cea486a5 /tools/perf/util/record.c | |
parent | 4f67336870f641daa485ea504777486e24a9aece (diff) |
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 <mingo@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-4y0tiuws62c64gp4cf0hme0m@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf/util/record.c')
-rw-r--r-- | tools/perf/util/record.c | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/tools/perf/util/record.c b/tools/perf/util/record.c index 1e97937b03a9..acabf54ceccb 100644 --- a/tools/perf/util/record.c +++ b/tools/perf/util/record.c @@ -5,6 +5,7 @@ #include "parse-events.h" #include <errno.h> #include <api/fs/fs.h> +#include <subcmd/parse-options.h> #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; +} |