Messages in this thread Patch in this message | | | Date | Thu, 27 Sep 2018 13:17:49 +0100 | From | Quentin Perret <> | Subject | Re: [PATCH v7 02/14] sched/cpufreq: Prepare schedutil for Energy Aware Scheduling |
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Hi Rafael,
Very sorry for the late reply ...
On Tuesday 18 Sep 2018 at 23:33:22 (+0200), Rafael J. Wysocki wrote: [...] > The new "type" argument should be documented. > > Also IMO using the special enum for it is quite confusing, because you > ever only check one value from it directly. What would be wrong with > using a plain "bool" instead?
So, this part of the code was originally proposed by Peter. I basically took it from the following message (hence the Suggested-by) which was fine by me:
https://lore.kernel.org/lkml/20180709120138.GQ2494@hirez.programming.kicks-ass.net/
Also, one of the things that has been mentioned during reviews was that other clients (such as cpuidle, IIRC) could potentially be interested in a 'global' cpu util value. And since those clients might have different needs than EAS or sugov, they might need a new entry in the enum.
So that's probably the main argument for the enum, it is easy to extend.
[...] > > +static unsigned long sugov_get_util(struct sugov_cpu *sg_cpu) > > +{ > > + struct rq *rq = cpu_rq(sg_cpu->cpu); > > + unsigned long util = cpu_util_cfs(rq); > > + > > + sg_cpu->max = arch_scale_cpu_capacity(NULL, sg_cpu->cpu); > > + sg_cpu->bw_dl = cpu_bw_dl(rq); > > + > > + return schedutil_freq_util(sg_cpu->cpu, util, FREQUENCY_UTIL); > > If you add a "max" argument to schedutil_freq_util(), you can avoid > the second (and arguably redundant) evaluation of > arch_scale_cpu_capacity() in there.
OK
[...] > > +enum schedutil_type { > > + FREQUENCY_UTIL, > > + ENERGY_UTIL, > > +}; > > As I said above, I would just use "bool" instead of this new enum (it > has two values too) or the new type needs to be documented.
As I said above, the enum has the good side of being easier to extend. So, if we care about that, I guess I'd rather add a doc for the new type.
> > + > > #ifdef CONFIG_CPU_FREQ_GOV_SCHEDUTIL > > +unsigned long schedutil_freq_util(int cpu, unsigned long util_cfs, > > + enum schedutil_type type); > > + > > static inline unsigned long cpu_bw_dl(struct rq *rq) > > { > > return (rq->dl.running_bw * SCHED_CAPACITY_SCALE) >> BW_SHIFT; > > @@ -2199,6 +2207,12 @@ static inline unsigned long cpu_util_rt(struct rq *rq) > > { > > return READ_ONCE(rq->avg_rt.util_avg); > > } > > +#else /* CONFIG_CPU_FREQ_GOV_SCHEDUTIL */ > > +static inline unsigned long schedutil_freq_util(int cpu, unsigned long util, > > + enum schedutil_type type) > > +{ > > + return util; > > +} > > #endif > > And I would add a wrapper around schedutil_freq_util(), called say > schedutil_energy_util(), that would pass a specific value as the > "type".
OK, that's fine by me.
Other than that, do you think these changes could be done later ? Or do you see that as mandatory before the patches can be picked up ?
Thanks, Quentin
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