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perf ftrace: Add option -D/--delay to delay tracing

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This adds an option '-D/--delay' to allow us to start tracing some times
later after workload is launched.

Signed-off-by: Changbin Du <changbin.du@gmail.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Link: http://lore.kernel.org/lkml/20200808023141.14227-16-changbin.du@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Changbin Du 2020-08-08 10:31:38 +08:00 committed by Arnaldo Carvalho de Melo
parent a8f87a5cb4
commit 6555c2f6db
2 changed files with 20 additions and 3 deletions
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4
tools/perf/Documentation/perf-ftrace.txt
View file

@ -39,6 +39,10 @@ OPTIONS
--pid=::
Trace on existing process id (comma separated list).
-D::
--delay::
Time (ms) to wait before starting tracing after program start.
-a::
--all-cpus::
Force system-wide collection. Scripts run without a <command>

19
tools/perf/builtin-ftrace.c
View file

@ -49,6 +49,7 @@ struct perf_ftrace {
int graph_noirqs;
int graph_verbose;
int graph_thresh;
unsigned int initial_delay;
};
struct filter_entry {
@ -596,13 +597,23 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv)
/* display column headers */
read_tracing_file_to_stdout("trace");
if (write_tracing_file("tracing_on", "1") < 0) {
pr_err("can't enable tracing\n");
goto out_close_fd;
if (!ftrace->initial_delay) {
if (write_tracing_file("tracing_on", "1") < 0) {
pr_err("can't enable tracing\n");
goto out_close_fd;
}
}
perf_evlist__start_workload(ftrace->evlist);
if (ftrace->initial_delay) {
usleep(ftrace->initial_delay * 1000);
if (write_tracing_file("tracing_on", "1") < 0) {
pr_err("can't enable tracing\n");
goto out_close_fd;
}
}
while (!done) {
if (poll(&pollfd, 1, -1) < 0)
break;
@ -827,6 +838,8 @@ int cmd_ftrace(int argc, const char **argv)
"size of per cpu buffer", parse_buffer_size),
OPT_BOOLEAN(0, "inherit", &ftrace.inherit,
"trace children processes"),
OPT_UINTEGER('D', "delay", &ftrace.initial_delay,
"ms to wait before starting tracing after program start"),
OPT_END()
};