Em Sun, May 10, 2020 at 11:06:26PM +0800, Changbin Du escreveu:
> This adds an option '-d/--delay' to allow us to start tracing some
> times later after workload is launched.
[acme@five perf]$ perf record -h delay
Usage: perf record [<options>] [<command>]
or: perf record [<options>] -- <command> [<options>]
-D, --delay <n> ms to wait before starting measurement after program
start
[acme@five perf]$
> Signed-off-by: Changbin Du <[email protected]>
> ---
> tools/perf/builtin-ftrace.c | 19 ++++++++++++++++---
> 1 file changed, 16 insertions(+), 3 deletions(-)
>
> diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
> index 8d04e5afe2d3..d376b37c53fc 100644
> --- a/tools/perf/builtin-ftrace.c
> +++ b/tools/perf/builtin-ftrace.c
> @@ -49,6 +49,7 @@ struct perf_ftrace {
> bool trace_children;
> unsigned buffer_size_kb;
> bool no_pager;
> + unsigned initial_delay;
> };
>
> struct filter_entry {
> @@ -617,13 +618,23 @@ 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;
> @@ -747,6 +758,8 @@ int cmd_ftrace(int argc, const char **argv)
> "size of per cpu buffer in kb"),
> OPT_BOOLEAN('P', "no-pager", &ftrace.no_pager,
> "Do not use pager"),
> + OPT_UINTEGER('d', "delay", &ftrace.initial_delay,
> + "Wait <n> ms before tracing"),
> OPT_END()
> };
>
> --
> 2.25.1
>
--
- Arnaldo
