On 2017-08-11 22:15:02 [+0000], Carol Wong wrote: > Hi Sebastian, Hi Carol, > I can't say that this change is responsible, but I see a dramatic difference when this patch is removed. Perhaps this is a red herring. For sure in my test case, 4.9.30-rt21 reports small latency and 4.9.33-rt23 reports large latency. > > > This change should be a nop if you don't change the task's CPU-mask > > while the task is in a migrate-disable section. Do I miss something? > > Is part of your workload changing cpu-affinity mask? > > > > The test program does not alter affinity masks. interesting. Could you add a trace-printk to check if it gets into that inner-loop if the mask changes and it needs to do the fixup? Other than that I don't see anything that could make any difference. > I performed the same test with 4.11.12-rt9 and observed large latencies under heavy cpu & net load. > > [localhost:~]# cyclictest -S -p98 --policy=rr > # /dev/cpu_dma_latency set to 0us > policy: rr: loadavg: 0.65 0.61 0.56 1/204 2206 > > T: 0 ( 2131) P:98 I:1000 C:11132138 Min: 1 Act: 1 Avg: 1 Max: 375 > T: 1 ( 2132) P:98 I:1500 C:7421425 Min: 1 Act: 1 Avg: 1 Max: 105 > T: 2 ( 2133) P:98 I:2000 C:5566069 Min: 1 Act: 1 Avg: 1 Max: 68 > T: 3 ( 2134) P:98 I:2500 C:4452855 Min: 1 Act: 2 Avg: 1 Max: 64 > > > Cheers, > Carol Sebastian -- 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
