Messages in this thread | | | Subject | Re: [PATCH 1/4] PM / EM: and devices to Energy Model | From | Lukasz Luba <> | Date | Tue, 21 Jan 2020 10:49:19 +0000 |
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On 1/21/20 10:08 AM, Quentin Perret wrote: > On Monday 20 Jan 2020 at 16:20:49 (+0000), Lukasz Luba wrote: >> On 1/20/20 3:28 PM, Quentin Perret wrote: >>> Agreed, this looks a bit confusing. It should be trivial to make >>> em_dev_get() (or whatever we end up calling it) work for CPUs too, >>> though. And we could always have a em_cpu_get(int cpu) API that is a >>> basically a wrapper around em_dev_get() for convenience. >> >> The problem not only here is that we have a CPU index 'int cpu' >> and if we ask for device like: >> >> struct device *dev = get_cpu_device(cpu); >> >> It might be not the same device that was used during the >> registration, when we had i.e. 4 CPUs for the same policy: >> >> int cpu_id = cpumask_first(policy->cpus); >> struct device *cpu_dev = get_cpu_device(cpu_id); >> em_register_perf_domain(cpu_dev, nr_opp, &em_cb); >> >> That's why the em_cpu_get() is different than em_get_pd(), mainly by: >> if (cpumask_test_cpu(cpu, em_span_cpus(em_pd))) >> >> It won't be simple wrapper, let me think how it could be handled >> differently than it is now. > > Right so I suppose the easiest solution would be to do the opposite of > my first suggestion. That is, make em_get_pd() call em_cpu_get() if the > device is a CPU device, or proceed to the PD list iteration for other > devices. And em_cpu_get() can remain as you originally suggested (that > is, iterate over the PDs and test the mask).
Exactly, something like: ---------------------------->8------------------------- 288 struct em_perf_domain *em_get_pd(struct device *dev) 289 { 290 struct em_device *em_dev; 291 292 if (IS_ERR_OR_NULL(dev)) 293 return NULL; 294 295 if (_is_cpu_device(dev)) 296 return em_cpu_get(dev->id); .... ------------------------8<-----------------------------
> > That should ensure em_get_pd() always works, em_cpu_get() is still there > handy for the scheduler and such, and the two EM lookup functions (for > CPUs or for devices) are kept cleanly separated. > > Thoughts ?
Agree. Then we can have these two functions and em_get_pd() will also work fine.
> > Thanks, > Quentin >
Regards, Lukasz
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