From: Patrick Bellasi <patrick.bellasi@arm.com>
To: douglas.raillard@arm.com
Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
mingo@redhat.com, peterz@infradead.org, quentin.perret@arm.com,
dietmar.eggemann@arm.com
Subject: Re: [RFC PATCH 1/7] PM: Introduce em_pd_get_higher_freq()
Date: Thu, 16 May 2019 13:42:00 +0100 [thread overview]
Message-ID: <20190516124200.opxczohjelhvrzmo@e110439-lin> (raw)
Message-ID: <20190516124200.gkC3D0YzCOXGdBQXmaovN0-N-uF8gHOEbnbhjOUkAHY@z> (raw)
In-Reply-To: <20190508174301.4828-2-douglas.raillard@arm.com>
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
next prev parent reply other threads:[~2019-05-16 12:42 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-08 17:42 [RFC PATCH 0/7] sched/cpufreq: Make schedutil energy aware douglas.raillard
2019-05-08 17:42 ` douglas.raillard
2019-05-08 17:42 ` [RFC PATCH 1/7] PM: Introduce em_pd_get_higher_freq() douglas.raillard
2019-05-08 17:42 ` douglas.raillard
2019-05-16 12:42 ` Patrick Bellasi [this message]
2019-05-16 12:42 ` Patrick Bellasi
2019-05-16 13:01 ` Quentin Perret
2019-05-16 13:01 ` Quentin Perret
2019-05-16 13:22 ` Patrick Bellasi
2019-05-16 13:22 ` Patrick Bellasi
2019-06-19 16:08 ` Douglas Raillard
2019-06-20 13:04 ` Patrick Bellasi
2019-06-21 10:17 ` Quentin Perret
2019-06-21 10:22 ` Quentin Perret
2019-05-16 13:06 ` Douglas Raillard
2019-05-16 13:06 ` Douglas Raillard
2019-05-08 17:42 ` [RFC PATCH 2/7] sched/cpufreq: Attach perf domain to sugov policy douglas.raillard
2019-05-08 17:42 ` douglas.raillard
2019-05-08 17:42 ` [RFC PATCH 3/7] sched/cpufreq: Hook em_pd_get_higher_power() into get_next_freq() douglas.raillard
2019-05-08 17:42 ` douglas.raillard
2019-05-08 17:42 ` [RFC PATCH 4/7] sched/cpufreq: Move up sugov_cpu_is_busy() douglas.raillard
2019-05-08 17:42 ` douglas.raillard
2019-05-08 17:42 ` [RFC PATCH 5/7] sched/cpufreq: sugov_cpu_is_busy for shared policy douglas.raillard
2019-05-08 17:42 ` douglas.raillard
2019-05-08 17:43 ` [RFC PATCH 6/7] sched/cpufreq: Improve sugov_cpu_is_busy accuracy douglas.raillard
2019-05-08 17:43 ` douglas.raillard
2019-05-16 12:55 ` Patrick Bellasi
2019-05-16 12:55 ` Patrick Bellasi
2019-06-19 16:19 ` Douglas Raillard
2019-06-20 11:05 ` Patrick Bellasi
2019-05-08 17:43 ` [RFC PATCH 7/7] sched/cpufreq: Boost schedutil frequency ramp up douglas.raillard
2019-05-08 17:43 ` douglas.raillard
2019-05-13 7:12 ` [RFC PATCH 0/7] sched/cpufreq: Make schedutil energy aware Viresh Kumar
2019-05-13 7:12 ` Viresh Kumar
2019-05-13 13:52 ` Douglas Raillard
2019-05-13 13:52 ` Douglas Raillard
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