Hi All, Is there any comments for the testing or the patch?
Thanks! Alex On 01/05/2017 11:48 PM, Alex Shi wrote: > On 01/05/2017 11:29 PM, Alex Shi wrote: >> > cpu_dma_latency is designed to keep all cpu awake from deep c-state. >> > That is good keep system with short response latency. But sometime we >> > don't need all cpu power especially in a more and more multi-core day. >> > So set all cpu restless that lead to a big power waste. >> > >> > A better way is to keep the short cpu response latency on needed cpu, >> > while let other unnecesscary cpus go to deep idle. That is this >> > patchset. We just use the pm_qos_resume_latency on cpu. Giving the >> > short cpu latency on appointed cpu via setting value on >> > /sys/devices/system/cpu/cpuX/power/pm_qos_resume_latency_us >> > We can set we wanted latency value according to the value of >> > /sys/devices/system/cpu/cpuX/cpuidle/stateX/latency. to just a bit >> > less related state's latency value. Then cpu can get to this state or >> > higher. >> > >> > Here is some testing data on my dragonboard 410c, the latency of state1 >> > is 280us. It has 4 cores. >> > >> > Benchmark: cyclictest -t 1 -n -i 10000 -l 1000 -q --latency=10000 >> > >> > without the patch: >> > Latency (us) Min: 87 Act: 209 Avg: 205 Max: 239 >> > With the patch and cpu0/power/pm_qos_resume_latency_us is lower than >> > 280us, like set to 279 >> > benchmark result on cpu0: >> > Latency (us) Min: 82 Act: 91 Avg: 95 Max: 110 >> > In repeat testing, the Avg latency always drop to half of vanilla kernel >> > value, as well as Max latency value, although sometime the Max latency >> > is similar with vanilla kernel.
