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Subject[PATCH] perf: add support for specifying profile cpu for record
Hi,

perf top supports a -C for setting the profile CPU, but perf record does
not. This adds the same option for perf record, allowing the user to
specify a specific target profile CPU.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 6da0992..8e85543 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -35,6 +35,7 @@ static const char *output_name = "perf.data";
static int group = 0;
static unsigned int realtime_prio = 0;
static int system_wide = 0;
+static int profile_cpu = -1;
static pid_t target_pid = -1;
static int inherit = 1;
static int force = 0;
@@ -425,6 +426,9 @@ try_again:

if (err == EPERM)
die("Permission error - are you root?\n");
+ else if (err == ENODEV && profile_cpu != -1)
+ die("No such device - did you specify an out-of-range"
+ " profile CPU?\n");

/*
* If it's cycles then fall back to hrtimer
@@ -554,9 +558,13 @@ static int __cmd_record(int argc, const char **argv)
if (pid == -1)
pid = getpid();

- open_counters(-1, pid);
- } else for (i = 0; i < nr_cpus; i++)
- open_counters(i, target_pid);
+ open_counters(profile_cpu, pid);
+ } else if (profile_cpu != -1)
+ open_counters(profile_cpu, target_pid);
+ else {
+ for (i = 0; i < nr_cpus; i++)
+ open_counters(i, target_pid);
+ }

if (file_new)
perf_header__write(header, output);
@@ -635,6 +643,8 @@ static const struct option options[] = {
"system-wide collection from all CPUs"),
OPT_BOOLEAN('A', "append", &append_file,
"append to the output file to do incremental profiling"),
+ OPT_INTEGER('C', "profile_cpu", &profile_cpu,
+ "CPU to profile on"),
OPT_BOOLEAN('f', "force", &force,
"overwrite existing data file"),
OPT_LONG('c', "count", &default_interval,
--
Jens Axboe



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