Messages in this thread | | | Date | Thu, 16 May 2019 13:42:00 +0100 | From | Patrick Bellasi <> | Subject | Re: [RFC PATCH 1/7] PM: Introduce em_pd_get_higher_freq() |
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On 08-May 18:42, douglas.raillard@arm.com wrote: > From: Douglas RAILLARD <douglas.raillard@arm.com> > > em_pd_get_higher_freq() returns a frequency greater or equal to the > provided one while taking into account a given cost margin. It also > skips inefficient OPPs that have a higher cost than another one with a > higher frequency.
It's worth to add a small description and definition of what we mean by "OPP efficiency". Despite being just an RFC, it could help to better understand what we are after.
[...]
> +/** + * em_pd_get_higher_freq() - Get the highest frequency that > does not exceed the > + * given cost margin compared to min_freq > + * @pd : performance domain for which this must be done > + * @min_freq : minimum frequency to return > + * @cost_margin : allowed margin compared to min_freq, as a per-1024 value. ^^^^^^^^ here...
> + * > + * Return: the chosen frequency, guaranteed to be at least as high as min_freq. > + */ > +static inline unsigned long em_pd_get_higher_freq(struct em_perf_domain *pd, > + unsigned long min_freq, unsigned long cost_margin) > +{ > + unsigned long max_cost = 0; > + struct em_cap_state *cs; > + int i; > + > + if (!pd) > + return min_freq; > + > + /* Compute the maximum allowed cost */ > + for (i = 0; i < pd->nr_cap_states; i++) { > + cs = &pd->table[i]; > + if (cs->frequency >= min_freq) { > + max_cost = cs->cost + (cs->cost * cost_margin) / 1024; ^^^^ ... end here we should probably better use SCHED_CAPACITY_SCALE instead of hard-coding in values, isn't it?
> + break; > + } > + } > +
[...]
Best, Patrick
-- #include <best/regards.h>
Patrick Bellasi
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