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