kybaaz/linux-xiaomi-chiron
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

preemptirq_delay_test: Add the burst feature and a sysfs trigger

Browse source 
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>
This commit is contained in:
Viktor Rosendahl (BMW) 2019-10-09 00:08:22 +02:00 • committed by Steven Rostedt (VMware)
parent 91edde2e6a
commit 793937236d
2 changed files with 128 additions and 22 deletions
Download patch file Download diff file Expand all files Collapse all files

6
kernel/trace/Kconfig
View file

@ -760,9 +760,9 @@ config PREEMPTIRQ_DELAY_TEST
configurable delay. The module busy waits for the duration of the
critical section.
For example, the following invocation forces a one-time irq-disabled
critical section for 500us:
modprobe preemptirq_delay_test test_mode=irq delay=500000
For example, the following invocation generates a burst of three
irq-disabled critical sections for 500us:
modprobe preemptirq_delay_test test_mode=irq delay=500 burst_size=3
If unsure, say N