From 6555c2f6db2196ef1b6d7149e7d342d0ba2ec57e Mon Sep 17 00:00:00 2001 From: Changbin Du Date: Sat, 8 Aug 2020 10:31:38 +0800 Subject: [PATCH] perf ftrace: Add option -D/--delay to delay tracing This adds an option '-D/--delay' to allow us to start tracing some times later after workload is launched. Signed-off-by: Changbin Du Acked-by: Namhyung Kim Cc: Jiri Olsa Cc: Peter Zijlstra Cc: Steven Rostedt (VMware) Link: http://lore.kernel.org/lkml/20200808023141.14227-16-changbin.du@gmail.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/Documentation/perf-ftrace.txt | 4 ++++ tools/perf/builtin-ftrace.c | 19 ++++++++++++++++--- 2 files changed, 20 insertions(+), 3 deletions(-) diff --git a/tools/perf/Documentation/perf-ftrace.txt b/tools/perf/Documentation/perf-ftrace.txt index 08216634d2bc..29c684b3b3fd 100644 --- a/tools/perf/Documentation/perf-ftrace.txt +++ b/tools/perf/Documentation/perf-ftrace.txt @@ -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 diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c index bc3b35d18167..5f9a9ebea0a2 100644 --- a/tools/perf/builtin-ftrace.c +++ b/tools/perf/builtin-ftrace.c @@ -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() }; -- 2.20.1