Messages in this thread | | | Date | Wed, 20 Jun 2018 08:58:09 +0100 | From | Quentin Perret <> | Subject | Re: [RFC PATCH v3 05/10] sched/topology: Reference the Energy Model of CPUs when available |
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On Tuesday 19 Jun 2018 at 20:42:50 (+0200), Peter Zijlstra wrote: > On Tue, Jun 19, 2018 at 06:13:17PM +0100, Quentin Perret wrote: > > Would replacing the static_key by a flag attached to the root_domain be > > reasonable ? > > Keep the static key as is, enable if any root domain needs it.
OK. So basically the semantics of the static key becomes: it is set if at least one root domain has a non-empty list of freq domains. And a root_domain has a non-empty list of frequency domains if it meets all conditions for EAS (SD_ASYM_CPUCAPACITY flag set, low complexity for the "portion" of the EM covering it, ...)
And then, checking the status of the list (empty or not) for a specific root domain can replace my flag I guess. I'll need to check that somewhere around select_task_rq_fair() in addition to the check on the static key to decide if a task can go in find_energy_efficient_cpu().
> > Sorry but I didn't understand that ... > > If you have only a single freq-domain, there is nothing to do, right?
Ah, right. Since we already agreed that all CPUs in a freq domain must have the same micro-arch, that's correct. Checking the presence of the SD_ASYM_CPUCAPACITY flag should cover this case I guess.
Thanks, Quentin
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