Quoting Peter Zijlstra (2015-03-26 03:41:50) > On Thu, Mar 26, 2015 at 10:21:24AM +0000, Juri Lelli wrote: > > - what about other sched classes? I know that this is very premature, > > but I can help but thinking that we'll need to do some sort of > > aggregation of requests, and if we put triggers in very specialized > > points we might lose some of the sched classes separation > > So for deadline we can do P state selection (as you're well aware) based > on the requested utilization. Not sure what to do for fifo/rr though, > they lack much useful information (as always). > > Now if we also look ahead to things like the ACPI CPPC stuff we'll see > that CFS and DL place different requirements on the hints. Where CFS > would like to hint a max perf (the hardware going slower due to the code > consisting of mostly stalls is always fine from a best effort energy > pov), the DL stuff would like to hint a min perf, seeing how it 'needs' > to provide a QoS. > > So we either need to carry this information along in a 'generic' way > between the various classes or put the hinting in every class. > > But yes, food for thought for sure.
I am a fan of putting the hints in every class. One idea I've been considering is that each sched class could have a small, simple cpufreq governor that expresses its constraints (max for cfs, min qos for dl) and then the cpufreq core Does The Right Thing. This would be a multi-governor approach, which requires some surgery to cpufreq core code, but I like the modularity and maintainability of it more than having one big super governor that has to satisfy every need. Regards, Mike -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
