Messages in this thread | | | Date | Fri, 2 Sep 2022 09:53:22 +0200 | Subject | Re: [RFC PATCH 1/1] sched/pelt: Introduce PELT multiplier | From | Dietmar Eggemann <> |
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On 29/08/2022 12:02, Peter Zijlstra wrote: > On Mon, Aug 29, 2022 at 10:08:13AM +0200, Peter Zijlstra wrote: >> On Mon, Aug 29, 2022 at 07:54:50AM +0200, Dietmar Eggemann wrote: >>> From: Vincent Donnefort <vincent.donnefort@arm.com>
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>>> +extern unsigned int sched_pelt_lshift; >>> + >>> +/* >>> + * absolute time |1 |2 |3 |4 |5 |6 | >>> + * @ mult = 1 --------****************--------****************- >>> + * @ mult = 2 --------********----------------********--------- >>> + * @ mult = 4 --------****--------------------****------------- >>> + * clock task mult >>> + * @ mult = 2 | | |2 |3 | | | | |5 |6 | | | >>> + * @ mult = 4 | | | | |2|3| | | | | | | | | | |5|6| | | | | | | >>> + * >>> + */ >>> +static inline void update_rq_clock_task_mult(struct rq *rq, s64 delta) >>> +{ >>> + delta <<= READ_ONCE(sched_pelt_lshift); >>> + >>> + rq->clock_task_mult += delta; >>> + >>> + update_rq_clock_pelt(rq, delta); >>> +} >> >> Hurmph... I'd almost go write you something like >> static_call()/static_branch() but for immediates. >> >> That said; given there's only like 3 options, perhaps a few >> static_branch() instances work just fine ? > > Also, I'm not at all sure about exposing that as an official sysctl. > > How about something like so?
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> void update_rq_clock(struct rq *rq) > --- a/kernel/sched/features.h > +++ b/kernel/sched/features.h > @@ -101,3 +101,6 @@ SCHED_FEAT(LATENCY_WARN, false) > > SCHED_FEAT(ALT_PERIOD, true) > SCHED_FEAT(BASE_SLICE, true) > + > +SCHED_FEAT(PELT_M2, false) > +SCHED_FEAT(PELT_M4, false)
The sched features interface would definitely be much less official but I think it's not useful for Android since they don't mount debugfs anymore.
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