tracing/timerlat: Print stacktrace in the IRQ handler if needed

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.

Link: https://lkml.kernel.org/r/fd04530ce98ae9270e41bb124ee5bf67b05ecfed.1652175637.git.bristot@kernel.org

Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Daniel Bristot de Oliveira 2022-05-10 11:45:24 +02:00 committed by Steven Rostedt (Google)
parent aa748949b4
commit 4dd2aea24e
2 changed files with 16 additions and 2 deletions

View file

@ -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
----------------------------

View file

@ -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);
}