On Fri, Aug 19, 2016 at 10:30:36AM +0800, Wanpeng Li wrote: > 2016-08-19 9:55 GMT+08:00 Steve Muckle <steve.muc...@linaro.org>: > > PELT scales its util_sum and util_avg values via > > arch_scale_cpu_capacity(). If that function is passed the CPU's sched > > domain then it will reduce the scaling capacity if SD_SHARE_CPUCAPACITY > > is set. PELT does not pass in the sd however. The other caller of > > arch_scale_cpu_capacity, update_cpu_capacity(), does. This means > > util_sum and util_avg scale beyond the CPU capacity on SMT. > > > > On an Intel i7-3630QM for example rq->cpu_capacity_orig is 589 but > > util_avg scales up to 1024. > > > > Fix this by passing in the sd in __update_load_avg() as well. > > I believe we notice this at least several months ago. > https://lkml.org/lkml/2016/5/25/228
Glad to see I'm not alone in thinking this is an issue. It causes an issue with schedutil, effectively doubling the apparent demand on SMT. I don't know the load balance code well enough offhand to say whether it's an issue there. cheers, Steve
