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authorArnaldo Carvalho de Melo <acme@redhat.com>2018-03-01 19:46:23 +0300
committerArnaldo Carvalho de Melo <acme@redhat.com>2018-03-05 15:58:43 +0300
commit67230479b2304be99e9451ee171aa288a112ea16 (patch)
treeef8566f22145f433806f62fc7eaf7817cea486a5 /tools/perf/perf.h
parent4f67336870f641daa485ea504777486e24a9aece (diff)
downloadlinux-67230479b2304be99e9451ee171aa288a112ea16.tar.xz
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/perf.h')
-rw-r--r--tools/perf/perf.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/tools/perf/perf.h b/tools/perf/perf.h
index cfe46236a5e5..a5df8bf73a68 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