Sebastian Andrzej Siewior writes: > Normal wake ups (like clock_nanosleep()) which are performed by normal > users can easily lead to 2ms latency spikes if (enough) hrtimer wakeups > are synchronized. > This patch moves all hrtimers wakeups to the softirq queue unless the > caller has a RT priority. > > Reported-by: Gratian Crisan <gratian.crisan@xxxxxx> I can confirm this patch fixes the original problem reported. I ran an overnight test (about 30 hours total) on two platforms using cyclictest + hrtimer stress load: configurable number of SCHED_OTHER threads doing random clock_nanosleep() in up to 1 mS intervals. Without this patch the max latency recorded was: * on dual core, Intel Atom E3825 @ 1.33GHz: 107 uS * on dual core, Zynq 7020 @ 667MHz: 261 uS With this patch the max numbers drop to: * on dual core, Intel Atom E3825 @ 1.33GHz: 66 uS * on dual core, Zynq 7020 @ 667MHz: 90 uS The max latency numbers with this patch are in-line with expectations for these platforms. Thank you so much, -Gratian -- 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
