On 2013/12/11 10:59, Howard Chu wrote: > I just upgraded a system from a 3.5 kernel to 3.12.3 and attempted to run > some new benchmarks on it. I see my test program ramps up in CPU usage for a > few seconds and then it gradually tails off. There's nothing obvious in the > user code to trigger this behavior, so I check dmesg, and see this: > > [ 55.037057] JFS: nTxBlock = 8192, nTxLock = 65536 > [163591.807470] perf samples too long (2758 > 2500), lowering > kernel.perf_event_max_sample_rate to 50000 > [164061.362762] perf samples too long (5204 > 5000), lowering > kernel.perf_event_max_sample_rate to 25000 > [167969.339513] [sched_delayed] sched: RT throttling activated > [182741.484637] perf samples too long (294588 > 10000), lowering > kernel.perf_event_max_sample_rate to 12500 > [182741.484726] INFO: NMI handler (perf_event_nmi_handler) took too long to > run: 36.665 msecs > [182822.633084] perf samples too long (292359 > 20000), lowering > kernel.perf_event_max_sample_rate to 6250 > [182905.606119] perf samples too long (290291 > 40000), lowering > kernel.perf_event_max_sample_rate to 3250 > [199384.293514] perf samples too long (288142 > 76923), lowering > kernel.perf_event_max_sample_rate to 1750 > [208507.301027] perf samples too long (285964 > 142857), lowering > kernel.perf_event_max_sample_rate to 1000 > [208528.976208] perf samples too long (283799 > 250000), lowering > kernel.perf_event_max_sample_rate to 500 > > Why is the kernel throttling my server? >
Because that is the default setting of the kernel. lxc34:/proc/sys/kernel # cat sched_rt_period_us 1000000 lxc34:/proc/sys/kernel # cat sched_rt_runtime_us 950000 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
