From: Dietmar Eggemann <dietmar.eggemann@arm.com>
To: Qais Yousef <qyousef@layalina.io>, Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Viresh Kumar <viresh.kumar@linaro.org>,
Vincent Guittot <vincent.guittot@linaro.org>
Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
Lukasz Luba <lukasz.luba@arm.com>
Subject: Re: [RFC PATCH 2/7] sched/pelt: Add a new function to approximate runtime to reach given util
Date: Wed, 6 Sep 2023 14:56:57 +0200 [thread overview]
Message-ID: <bad29fb0-c734-853b-492b-ce2d01a293c5@arm.com> (raw)
In-Reply-To: <20230827233203.1315953-3-qyousef@layalina.io>
On 28/08/2023 01:31, Qais Yousef wrote:
> It is basically the ramp-up time from 0 to a given value. Will be used
> later to implement new tunable to control response time for schedutil.
>
> Signed-off-by: Qais Yousef (Google) <qyousef@layalina.io>
> ---
> kernel/sched/pelt.c | 21 +++++++++++++++++++++
> kernel/sched/sched.h | 1 +
> 2 files changed, 22 insertions(+)
>
> diff --git a/kernel/sched/pelt.c b/kernel/sched/pelt.c
> index 50322005a0ae..f673b9ab92dc 100644
> --- a/kernel/sched/pelt.c
> +++ b/kernel/sched/pelt.c
> @@ -487,3 +487,24 @@ unsigned long approximate_util_avg(unsigned long util, u64 delta)
>
> return sa.util_avg;
> }
> +
> +/*
> + * Approximate the required amount of runtime in ms required to reach @util.
> + */
> +u64 approximate_runtime(unsigned long util)
> +{
> + struct sched_avg sa = {};
> + u64 delta = 1024; // period = 1024 = ~1ms
> + u64 runtime = 0;
> +
> + if (unlikely(!util))
> + return runtime;
> +
> + while (sa.util_avg < util) {
> + accumulate_sum(delta, &sa, 0, 0, 1);
> + ___update_load_avg(&sa, 0);
> + runtime++;
> + }
> +
> + return runtime;
> +}
S_n = S_inv * (1 - 0.5^(t/hl))
t = hl * ln(1 - Sn/S_inv)/ln(0.5)
(1) for a little CPU (capacity_orig = 446)
t = 32ms * ln(1 - 446/1024)/ln(0.5)
t = 26ms
(2) for a big CPU (capacity = 1023 (*instead of 1024 since ln(0) not
defined
t = 32ms * ln(1 - 1023/1024)/ln(0.5)
t = 320ms
[...]
next prev parent reply other threads:[~2023-09-06 12:57 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-27 23:31 [RFC PATCH 0/7] sched: cpufreq: Remove magic margins Qais Yousef
2023-08-27 23:31 ` [RFC PATCH 1/7] sched/pelt: Add a new function to approximate the future util_avg value Qais Yousef
2023-09-06 12:56 ` Dietmar Eggemann
2023-09-06 21:19 ` Qais Yousef
2023-09-07 11:12 ` Dietmar Eggemann
2023-09-10 19:58 ` Qais Yousef
2023-09-13 17:22 ` Dietmar Eggemann
2023-09-16 19:49 ` Qais Yousef
2023-09-16 19:52 ` Qais Yousef
2023-08-27 23:31 ` [RFC PATCH 2/7] sched/pelt: Add a new function to approximate runtime to reach given util Qais Yousef
2023-09-06 12:56 ` Dietmar Eggemann [this message]
2023-09-06 20:44 ` Dietmar Eggemann
2023-09-06 21:38 ` Qais Yousef
2023-09-15 9:15 ` Hongyan Xia
2023-09-16 19:56 ` Qais Yousef
2023-08-27 23:31 ` [RFC PATCH 3/7] sched/fair: Remove magic margin in fits_capacity() Qais Yousef
2023-09-06 14:38 ` Dietmar Eggemann
2023-09-06 21:45 ` Qais Yousef
2023-08-27 23:32 ` [RFC PATCH 4/7] sched: cpufreq: Remove magic 1.25 headroom from apply_dvfs_headroom() Qais Yousef
2023-09-07 11:34 ` Peter Zijlstra
2023-09-10 19:23 ` Qais Yousef
2023-08-27 23:32 ` [RFC PATCH 5/7] sched/schedutil: Add a new tunable to dictate response time Qais Yousef
2023-09-06 21:13 ` Dietmar Eggemann
2023-09-06 21:52 ` Qais Yousef
2023-09-07 11:44 ` Peter Zijlstra
2023-09-10 19:25 ` Qais Yousef
2023-08-27 23:32 ` [RFC PATCH 6/7] sched/pelt: Introduce PELT multiplier Qais Yousef
2023-08-27 23:32 ` [RFC PATCH 7/7] cpufreq: Change default transition delay to 2ms Qais Yousef
2023-09-06 9:18 ` [RFC PATCH 0/7] sched: cpufreq: Remove magic margins Lukasz Luba
2023-09-06 21:18 ` Qais Yousef
2023-09-07 7:48 ` Lukasz Luba
2023-09-07 11:53 ` Peter Zijlstra
2023-09-07 13:06 ` Lukasz Luba
2023-09-07 13:29 ` Peter Zijlstra
2023-09-07 13:33 ` Lukasz Luba
2023-09-07 13:38 ` Peter Zijlstra
2023-09-07 13:45 ` Lukasz Luba
2023-09-08 12:51 ` Daniel Bristot de Oliveira
2023-09-12 11:57 ` Lukasz Luba
2023-09-10 18:20 ` Qais Yousef
2023-09-10 18:14 ` Qais Yousef
2023-09-07 13:26 ` Peter Zijlstra
2023-09-07 13:57 ` Lukasz Luba
2023-09-07 14:29 ` Peter Zijlstra
2023-09-07 14:42 ` Lukasz Luba
2023-09-07 20:16 ` Peter Zijlstra
2023-09-12 11:51 ` Lukasz Luba
2023-09-12 14:01 ` Vincent Guittot
2023-09-13 9:53 ` Lukasz Luba
2023-09-12 14:28 ` Peter Zijlstra
2023-09-10 19:06 ` Qais Yousef
2023-09-10 18:46 ` Qais Yousef
2023-09-07 13:08 ` Peter Zijlstra
2023-09-08 0:17 ` Qais Yousef
2023-09-08 7:40 ` Dietmar Eggemann
2023-09-08 14:07 ` Qais Yousef
2023-09-12 17:18 ` Dietmar Eggemann
2023-09-16 19:38 ` Qais Yousef
2023-09-08 10:25 ` Peter Zijlstra
2023-09-08 13:33 ` Qais Yousef
2023-09-08 13:58 ` Peter Zijlstra
2023-09-08 13:59 ` Peter Zijlstra
2023-09-08 14:11 ` Qais Yousef
2023-09-10 21:17 ` Qais Yousef
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