On Fri, 3 Mar 2017, Julia Cartwright wrote: > > Without PREEMPT_RT_FULL enabled, the critical section is executed with > "raw" spinlocks, and is therefore non-preemptible. However, with > RT_FULL, the preemptibility of the section leads to the "bounce". > > That should make it clear why ktimersoftd would be PI boosted, as well. > > Now, it isn't clear to me why the affinitized scenario appears to make > this happen more frequently... Nor do I have a handle on what to do to > fix this (if anything). The point here is: perf stat taskset 1 cyclictest -t1 will make the control thread of cyclictest affine to cpu 0 and also the measuring thread. perf stat counts the context switches of both. CPU 0 cyclictest-control --> Interrupt ksoftirqd cyclictest-measure rearm timer sleep cyclictest-control .... versus a non affine scenario CPU0 CPU1 CPU2 cyclictest-control interrupt ksoftirqd --> cyclictest-measure rearm timer sleep interrupt cyclicttest <-- ksoftirqd -measure Thanks, tglx -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
