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Subject[PATCH 12/19] perf ftrace: add support for tracing children processes
Date
This adds an option '--trace-children' to allow us trace children
processes spawned by our target.

Signed-off-by: Changbin Du <changbin.du@gmail.com>
---
tools/perf/builtin-ftrace.c | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)

diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
index ab76ba66bd9e..8fd95c109fe8 100644
--- a/tools/perf/builtin-ftrace.c
+++ b/tools/perf/builtin-ftrace.c
@@ -46,6 +46,7 @@ struct perf_ftrace {
bool funcgraph_tail;
bool long_info;
unsigned tracing_thresh;
+ bool trace_children;
};

struct filter_entry {
@@ -200,6 +201,7 @@ static void reset_tracing_options(struct perf_ftrace *ftrace __maybe_unused)
write_tracing_option_file("irq-info", "0");
write_tracing_option_file("userstacktrace", "0");
write_tracing_option_file("sym-userobj", "0");
+ write_tracing_option_file("function-fork", "0");
}

static int reset_tracing_files(struct perf_ftrace *ftrace __maybe_unused)
@@ -441,6 +443,17 @@ static int set_tracing_funcgraph_tail(struct perf_ftrace *ftrace)
return 0;
}

+static int set_tracing_trace_children(struct perf_ftrace *ftrace)
+{
+ if (!ftrace->trace_children)
+ return 0;
+
+ if (write_tracing_option_file("function-fork", "1") < 0)
+ return -1;
+
+ return 0;
+}
+
static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv)
{
char *trace_file;
@@ -539,6 +552,11 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv)
goto out_reset;
}

+ if (set_tracing_trace_children(ftrace) < 0) {
+ pr_err("failed to set tracing option function-fork\n");
+ goto out_reset;
+ }
+
if (write_tracing_file("current_tracer", ftrace->tracer) < 0) {
pr_err("failed to set current_tracer to %s\n", ftrace->tracer);
goto out_reset;
@@ -686,6 +704,8 @@ int cmd_ftrace(int argc, const char **argv)
"Show process names, PIDs, timestamps, irq-info if available"),
OPT_UINTEGER(0, "tracing-thresh", &ftrace.tracing_thresh,
"Only show functions of which the duration is greater than <n>µs"),
+ OPT_BOOLEAN(0, "trace-children", &ftrace.trace_children,
+ "Trace children processes"),
OPT_END()
};

--
2.25.1
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