Книга: Embedded Linux Primer: A Practical, Real-World Approach
17.4.5. Interrupt Off Timing
17.4.5. Interrupt Off Timing
To enable measurement of maximum interrupt off timing, configure your kernel with CRITICAL_IRQSOFF_TIMING enabled. This option measures time spent in critical sections with irqs disabled. This feature works in the same way as wakeup latency timing. To enable the measurement, do the following as root:
# echo '0' >/proc/sys/kernel/preempt_max_latency
When this /proc file is set to zero, each successive maximum interrupt off timing result is written to this file. To read the current maximum, simply display the value:
# cat /proc/sys/kernel/preempt_max_latency
97
You will notice that the latency measurements for both wakeup latency and interrupt off latency are enabled and displayed using the same /proc file. This means, of course, that only one measurement can be configured at a time, or the results might not be valid. Because these measurements add significant runtime overhead, it isn't wise to enable them all at once anyway.
Оглавление книги
- 17.4.6. Interrupt Off History
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