On Wed, May 16, 2018 at 09:16:40AM +0200, Peter Zijlstra wrote: > On Tue, May 15, 2018 at 09:49:03PM -0700, Srinivas Pandruvada wrote: > > intel_pstate has two operating modes: active and passive. In "active" > > mode, the in-built scaling governor is used and in "passive" mode, > > the driver can be used with any governor like "schedutil". In "active" > > mode the utilization values from schedutil is not used and there is > > a requirement from high performance computing use cases, not to read > > any APERF/MPERF MSRs. In this case no need to use CPU cycles for > > frequency invariant accounting by reading APERF/MPERF MSRs. > > With this change frequency invariant account is only enabled in > > "passive" mode. > > WTH is active/passive? Is passive when we select performance governor?
Bah, I cannot read it seems. active is when we use the intel_pstate governor and passive is when we use schedutil and only use intel_pstate as a driver. > Also; you have to explain why using APERF/MPERF is bad in that case. Why > do they care if we read those MSRs during the tick? That still stands.. this needs to be properly explained.
