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From: Tom Gebhardt <tomge68@gmail.com>
To: Christian Loehle <christian.loehle@arm.com>
Cc: Qais Yousef <qyousef@layalina.io>,
	linux-kernel@vger.kernel.org,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>
Subject: Re: [PATCH v2 00/13] sched/fair/schedutil: Better manage system response time
Date: Tue, 19 May 2026 09:46:35 +0200	[thread overview]
Message-ID: <06fa37519f4cd1c1f4d1903c37680ae1.tomge68@gmail.com> (raw)
In-Reply-To: <a7645295-be9d-48d0-9490-36adf0b69f44@arm.com>

Hi Christian,

Thanks for trying to replicate -- and your result actually confirms the
picture: without Peter's ttwu series, Vincent's fix has no measurable
effect. That's consistent with what I see: the improvement from patch 12 /
Vincent's fix only shows up *on top of* the ttwu patches, not standalone.

So the interaction seems to be:

  ttwu patches alone        → −22% vs. 6.6 at OC
  ttwu + util_est fix       → −1.2% vs. 6.6 at OC  (large recovery)
  vanilla 7.0 (no ttwu)     → −26% vs. 6.6 at OC
  vanilla 7.0 + util_est    → no significant change  (your result)

This suggests the ttwu series changes something in the dequeue path that
exposes the util_est timing issue, and the fix only matters in that context.

I would be happy to push the exact tree so you can reproduce it directly.
However, I currently have a hardware issue with the Pi and cannot test or
prepare the tree right now. I'll push it to GitHub as soon as I'm back up
and let you know here.

Tom

  reply	other threads:[~2026-05-19  7:46 UTC|newest]

Thread overview: 53+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-05-04  1:59 Qais Yousef
2026-05-04  1:59 ` [PATCH v2 01/13] sched: cpufreq: Rename map_util_perf to sugov_apply_dvfs_headroom Qais Yousef
2026-05-04  1:59 ` [PATCH v2 02/13] sched/pelt: Add a new function to approximate the future util_avg value Qais Yousef
2026-05-04  1:59 ` [PATCH v2 03/13] sched/pelt: Add a new function to approximate runtime to reach given util Qais Yousef
2026-06-04  8:50   ` Vincent Guittot
2026-07-14 13:37     ` Qais Yousef
2026-05-04  1:59 ` [PATCH v2 04/13] sched/fair: Remove magic hardcoded margin in fits_capacity() Qais Yousef
2026-06-04 10:08   ` Vincent Guittot
2026-07-14 14:04     ` Qais Yousef
2026-05-04  1:59 ` [PATCH v2 05/13] sched: cpufreq: Remove magic 1.25 headroom from sugov_apply_dvfs_headroom() Qais Yousef
2026-05-04  1:59 ` [PATCH v2 06/13] sched/fair: Extend util_est to improve rampup time Qais Yousef
2026-05-04  1:59 ` [PATCH v2 07/13] sched/fair: util_est: Take into account periodic tasks Qais Yousef
2026-05-04  1:59 ` [PATCH v2 RFC 08/13] sched/qos: Add a new sched-qos interface Qais Yousef
2026-05-06 20:38   ` Tim Chen
2026-05-07  9:55     ` Qais Yousef
2026-05-07 14:20       ` Chen, Yu C
2026-05-09  9:39         ` Qais Yousef
2026-05-11 10:57   ` Peter Zijlstra
2026-05-12  7:58     ` Qais Yousef
2026-05-12  8:30       ` Peter Zijlstra
2026-05-12  8:47         ` Qais Yousef
2026-05-19  9:47   ` Peter Zijlstra
2026-05-19 10:56     ` Qais Yousef
2026-06-23 10:28   ` zhidao su
2026-07-14 14:17     ` Qais Yousef
2026-05-04  1:59 ` [PATCH v2 09/13] sched/qos: Add rampup multiplier QoS Qais Yousef
2026-05-11 11:03   ` Peter Zijlstra
2026-05-12  7:59     ` Qais Yousef
2026-05-12  8:37       ` Christian Loehle
2026-05-12  8:53         ` Qais Yousef
2026-06-18  8:30   ` zhidao su (Xiaomi)
2026-07-14 14:08     ` Qais Yousef
2026-05-04  2:00 ` [PATCH v2 10/13] sched/fair: Disable util_est when rampup_multiplier is 0 Qais Yousef
2026-05-04  2:00 ` [PATCH v2 11/13] sched/fair: Don't mess with util_avg post init Qais Yousef
2026-05-04  2:00 ` [PATCH v2 12/13] sched/fair: Call update_util_est() after dequeue_entities() Qais Yousef
2026-05-04  2:00 ` [PATCH v2 RFC 13/13] sched/pelt: Always allow load updates Qais Yousef
2026-05-11 17:58 ` [PATCH v2 00/13] sched/fair/schedutil: Better manage system response time John Stultz
2026-05-12  8:01   ` Qais Yousef
2026-05-13 15:09 ` Tom Gebhardt
2026-05-15  1:42   ` Qais Yousef
2026-05-15  8:24     ` Tom Gebhardt
2026-05-15 10:01       ` Christian Loehle
2026-05-15 13:57         ` Tom Gebhardt
2026-05-16 13:43           ` Christian Loehle
2026-05-19  7:46             ` Tom Gebhardt [this message]
2026-05-25  7:25             ` Tom Gebhardt
2026-05-28  7:38               ` Christian Loehle
2026-05-28 11:08                 ` Tom Gebhardt
2026-05-16  3:01       ` Qais Yousef
2026-05-28 12:50         ` Tom Gebhardt
2026-05-29  1:43           ` Qais Yousef
2026-05-29  7:53             ` Tom Gebhardt
2026-05-31  2:35               ` Qais Yousef

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