preemptirq_delay_test: Add the burst feature and a sysfs trigger
This burst feature enables the user to generate a burst of preempt/irqsoff latencies. This makes it possible to test whether we are able to detect latencies that systematically occur very close to each other. The maximum burst size is 10. We also create 10 identical test functions, so that we get 10 different backtraces; this is useful when we want to test whether we can detect all the latencies in a burst. Otherwise, there would be no easy way of differentiating between which latency in a burst was captured by the tracer. In addition, there is a sysfs trigger, so that it's not necessary to reload the module to repeat the test. The trigger will appear as /sys/kernel/preemptirq_delay_test/trigger in sysfs. Link: http://lkml.kernel.org/r/20191008220824.7911-3-viktor.rosendahl@gmail.com Reviewed-by:Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by:
Viktor Rosendahl (BMW) <viktor.rosendahl@gmail.com> Signed-off-by:
Steven Rostedt (VMware) <rostedt@goodmis.org>
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