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From: Qais Yousef <qyousef@layalina.io>
To: 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>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
	Lukasz Luba <lukasz.luba@arm.com>,
	Qais Yousef <qyousef@layalina.io>
Subject: [RFC PATCH 7/7] cpufreq: Change default transition delay to 2ms
Date: Mon, 28 Aug 2023 00:32:03 +0100	[thread overview]
Message-ID: <20230827233203.1315953-8-qyousef@layalina.io> (raw)
In-Reply-To: <20230827233203.1315953-1-qyousef@layalina.io>

10ms is too high for today's hardware, even low end ones. This default
end up being used a lot on Arm machines at least. Pine64, mac mini and
pixel 6 all end up with 10ms rate_limit_us when using schedutil, and
it's too high for all of them.

Change the default to 2ms which should be 'pessimistic' enough for worst
case scenario, but not too high for platforms with fast DVFS hardware.

Signed-off-by: Qais Yousef (Google) <qyousef@layalina.io>
---
 drivers/cpufreq/cpufreq.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 50bbc969ffe5..d8fc33b7f2d2 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -579,11 +579,11 @@ unsigned int cpufreq_policy_transition_delay_us(struct cpufreq_policy *policy)
 		 * for platforms where transition_latency is in milliseconds, it
 		 * ends up giving unrealistic values.
 		 *
-		 * Cap the default transition delay to 10 ms, which seems to be
+		 * Cap the default transition delay to 2 ms, which seems to be
 		 * a reasonable amount of time after which we should reevaluate
 		 * the frequency.
 		 */
-		return min(latency * LATENCY_MULTIPLIER, (unsigned int)10000);
+		return min(latency * LATENCY_MULTIPLIER, (unsigned int)(2*MSEC_PER_SEC));
 	}
 
 	return LATENCY_MULTIPLIER;
-- 
2.34.1


  parent reply	other threads:[~2023-08-27 23:33 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
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 ` Qais Yousef [this message]
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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