If print_stack and stop_tracing_us are set, and stop_tracing_us is hit
with latency higher than or equal to print_stack, print the
stack at the IRQ handler as it is useful to define the root cause for
the IRQ latency.
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx>
---
Documentation/trace/timerlat-tracer.rst | 5 +++--
kernel/trace/trace_osnoise.c | 13 +++++++++++++
2 files changed, 16 insertions(+), 2 deletions(-)
diff --git a/Documentation/trace/timerlat-tracer.rst b/Documentation/trace/timerlat-tracer.rst
index 64d1fe6e9b93..d643c95c01eb 100644
--- a/Documentation/trace/timerlat-tracer.rst
+++ b/Documentation/trace/timerlat-tracer.rst
@@ -74,8 +74,9 @@ directory. The timerlat configs are:
- stop_tracing_total_us: stop the system tracing if a
timer latency at the *thread* context is higher than the configured
value happens. Writing 0 disables this option.
- - print_stack: save the stack of the IRQ occurrence, and print
- it after the *thread context* event".
+ - print_stack: save the stack of the IRQ occurrence. The stack is printed
+ after the *thread context* event, or at the IRQ handler if *stop_tracing_us*
+ is hit.
timerlat and osnoise
----------------------------
diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c
index 6494ca27ea6f..9b204ee3c6f5 100644
--- a/kernel/trace/trace_osnoise.c
+++ b/kernel/trace/trace_osnoise.c
@@ -1580,6 +1580,19 @@ static enum hrtimer_restart timerlat_irq(struct hrtimer *timer)
if (osnoise_data.stop_tracing) {
if (time_to_us(diff) >= osnoise_data.stop_tracing) {
+
+ /*
+ * At this point, if stop_tracing is set and <= print_stack,
+ * print_stack is set and would be printed in the thread handler.
+ *
+ * Thus, print the stack trace as it is helpful to define the
+ * root cause of an IRQ latency.
+ */
+ if (osnoise_data.stop_tracing <= osnoise_data.print_stack) {
+ timerlat_save_stack(0);
+ timerlat_dump_stack(time_to_us(diff));
+ }
+
osnoise_stop_tracing();
notify_new_max_latency(diff);
}
--
2.32.0
|