[PATCH 18/19] perf ftrace: add option --latency-format to display more info about delay

From: Changbin Du
Date: Sun May 10 2020 - 11:10:36 EST


This is for the function graph tracer to display more info about latency.
The execution context is shown in this case.

$ sudo perf ftrace -G --latency-format
\# tracer: function_graph
\#
1) .... | 0.992 us | mutex_unlock();
1) .... | 1.404 us | __fsnotify_parent();
1) .... | 1.023 us | fsnotify();
1) .... | 0.335 us | __sb_end_write();
1) d... | 0.439 us | fpregs_assert_state_consistent();
1) d... | | do_syscall_64() {
1) .... | | __x64_sys_close() {

Signed-off-by: Changbin Du <changbin.du@xxxxxxxxx>
---
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 d376b37c53fc..fd8e2f305136 100644
--- a/tools/perf/builtin-ftrace.c
+++ b/tools/perf/builtin-ftrace.c
@@ -44,6 +44,7 @@ struct perf_ftrace {
bool nosleep_time;
bool nofuncgraph_irqs;
bool funcgraph_tail;
+ bool latency_format;
bool long_info;
unsigned tracing_thresh;
bool trace_children;
@@ -217,6 +218,7 @@ static void reset_tracing_options(struct perf_ftrace *ftrace __maybe_unused)
write_tracing_option_file("sleep-time", "1");
write_tracing_option_file("funcgraph-irqs", "1");
write_tracing_option_file("funcgraph-tail", "0");
+ write_tracing_option_file("latency-format", "0");
write_tracing_option_file("funcgraph-proc", "0");
write_tracing_option_file("funcgraph-abstime", "0");
write_tracing_option_file("irq-info", "0");
@@ -456,6 +458,17 @@ static int set_tracing_funcgraph_tail(struct perf_ftrace *ftrace)
return 0;
}

+static int set_tracing_latency_format(struct perf_ftrace *ftrace)
+{
+ if (!ftrace->latency_format)
+ return 0;
+
+ if (write_tracing_option_file("latency-format", "1") < 0)
+ return -1;
+
+ return 0;
+}
+
static int set_tracing_trace_children(struct perf_ftrace *ftrace)
{
if (!ftrace->trace_children)
@@ -579,6 +592,11 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv)
goto out_reset;
}

+ if (set_tracing_latency_format(ftrace) < 0) {
+ pr_err("failed to set tracing option latency-format\n");
+ goto out_reset;
+ }
+
if (set_tracing_trace_children(ftrace) < 0) {
pr_err("failed to set tracing option function-fork\n");
goto out_reset;
@@ -748,6 +766,8 @@ int cmd_ftrace(int argc, const char **argv)
"Ignore functions that happen inside interrupt (function_graph only)"),
OPT_BOOLEAN(0, "funcgraph-tail", &ftrace.funcgraph_tail,
"Show function tails comment (function_graph only)"),
+ OPT_BOOLEAN(0, "latency-format", &ftrace.latency_format,
+ "displays additional information about the latency (function_graph only)"),
OPT_BOOLEAN('l', "long-info", &ftrace.long_info,
"Show process names, PIDs, timestamps, irq-info if available"),
OPT_UINTEGER(0, "tracing-thresh", &ftrace.tracing_thresh,
--
2.25.1