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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>
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2 changed files with 16 additions and 2 deletions
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@ -74,8 +74,9 @@ directory. The timerlat configs are:
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- stop_tracing_total_us: stop the system tracing if a
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timer latency at the *thread* context is higher than the configured
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value happens. Writing 0 disables this option.
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- print_stack: save the stack of the IRQ occurrence, and print
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it after the *thread context* event".
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- print_stack: save the stack of the IRQ occurrence. The stack is printed
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after the *thread context* event, or at the IRQ handler if *stop_tracing_us*
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is hit.
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timerlat and osnoise
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----------------------------
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@ -1580,6 +1580,19 @@ static enum hrtimer_restart timerlat_irq(struct hrtimer *timer)
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if (osnoise_data.stop_tracing) {
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if (time_to_us(diff) >= osnoise_data.stop_tracing) {
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/*
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* At this point, if stop_tracing is set and <= print_stack,
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* print_stack is set and would be printed in the thread handler.
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*
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* Thus, print the stack trace as it is helpful to define the
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* root cause of an IRQ latency.
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*/
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if (osnoise_data.stop_tracing <= osnoise_data.print_stack) {
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timerlat_save_stack(0);
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timerlat_dump_stack(time_to_us(diff));
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}
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osnoise_stop_tracing();
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notify_new_max_latency(diff);
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}
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