On Wed, Mar 16, 2016 at 9:53 AM, Peter Zijlstra <pet...@infradead.org> wrote: > On Wed, Mar 16, 2016 at 09:29:59AM +0100, Vincent Guittot wrote: >> I wonder if it's really worth passing per sched_class request to >> sched_util ? sched_util is about selecting a frequency based on the >> utilization of the CPU, it only needs a value that reflect the whole >> utilization. Can't we sum (or whatever the formula we want to apply) >> utilizations before calling cpufreq_update_util > > So I've thought the same; but I'm conflicted, its a shame to compute > anything if the call then doesn't do anything with it. > > And keeping a structure of all the various numbers to pass in also has > cost of yet another cacheline to touch.
In principle we can use high-order bits of util and max to encode the information on where they come from. Of course, that translates to additional ifs in the governor, but I guess they are unavoidable anyway.
