Messages in this thread | | | Subject | Re: [PATCH v10 1/3] cpufreq: Add mechanism for registering utilization update callbacks | From | Srinivas Pandruvada <> | Date | Fri, 19 Feb 2016 08:42:09 -0800 |
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On Fri, 2016-02-19 at 08:09 +0000, Juri Lelli wrote: Hi Juri, > > > Hi Rafael, > > On 18/02/16 21:22, Rafael J. Wysocki wrote: > > On Mon, Feb 15, 2016 at 10:47 PM, Rafael J. Wysocki <rjw@rjwysocki. > > net> wrote: > > > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > > > [...]
> However, I still don't quite get why we want to introduce an > interface > for explicit passing of util and max if we are not using such > parameters > yet. Also, I couldn't find any indication of how such parameters will > be > used in the future. If what we need today is a periodic kick for > cpufreq > governors that need it, we should simply do how we already do for RT > and > DL, IMHO. Also because the places where the current hooks reside > might > not be the correct and useful one once we'll start using the > utilization > parameters. I could probably make a case for DL where we should place > hooks in admission control path (or somewhere else when more > sophisticated mechanisms we'll be in place) rather then in the > periodic > tick. We did experiments using util/max in intel_pstate. For some benchmarks there were regression of 4 to 5%, for some benchmarks it performed at par with getting utilization from the processor. Further optimization in the algorithm is possible and still in progress. Idea is that we can change P-State fast enough and be more reactive. Once I have good data, I will send to this list. The algorithm can be part of the cpufreq governor too.
Thanks, Srinivas
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