From: Peter Zijlstra <peterz@infradead.org>
To: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Krzysztof Kozlowski <krzk@kernel.org>,
linux-kernel@vger.kernel.org, linux-tip-commits@vger.kernel.org,
John Stultz <jstultz@google.com>,
x86@kernel.org,
'Linux Samsung SOC' <linux-samsung-soc@vger.kernel.org>,
Mark Rutland <mark.rutland@arm.com>
Subject: Re: [tip: sched/urgent] sched/deadline: Fix dl_server getting stuck
Date: Thu, 9 Oct 2025 11:26:48 +0200 [thread overview]
Message-ID: <20251009092648.GW3419281@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <eae77bd0-d874-4ddf-88d7-c1ab75358f91@samsung.com>
On Mon, Sep 29, 2025 at 05:19:27PM +0200, Marek Szyprowski wrote:
> Thanks for some hints, but unfortunately ARM64 doesn't support
> earlyprintk, so I was not able to use this method.
I've been told it is called earlycon= on arm; still sets up
early_console and make early_printk() work.
My patches just re-route everything printk() into early_printk().
> However I've played a bit with this code and found that this strange
> wake-up of the CPU7 seems to be caused by the timer. If I restore
>
> if (!dl_se->server_has_tasks(dl_se))
> return HRTIMER_NORESTART;
>
> part in the dl_server_timer, the everything works again as before this
> patch.
Right, so something on your platform is not working right. Stray timers
should not wake up CPUs.
> This issue is however not Exynos5433 ARM 64bit specific. Similar lockup
> happens on Exynos5422 ARM 32bit boards, although there is no message in
> that case. Does it mean that handling of the hrtimers on Exynos boards
> is a bit broken in the context of CPU hotplug?
There is this thread:
https://lkml.kernel.org/r/20251009080007.GH3245006@noisy.programming.kicks-ass.net
I suspect this might be the same issue and we've made a little progress
there.
next prev parent reply other threads:[~2025-10-09 9:26 UTC|newest]
Thread overview: 101+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-07-02 11:49 [PATCH v2 00/12] sched: Address schbench regression Peter Zijlstra
2025-07-02 11:49 ` [PATCH v2 01/12] sched/psi: Optimize psi_group_change() cpu_clock() usage Peter Zijlstra
2025-07-15 19:11 ` Chris Mason
2025-07-16 6:06 ` K Prateek Nayak
2025-07-16 6:53 ` Beata Michalska
2025-07-16 10:40 ` Peter Zijlstra
2025-07-16 14:54 ` Johannes Weiner
2025-07-16 16:27 ` Chris Mason
2025-07-23 4:16 ` Aithal, Srikanth
2025-07-25 5:13 ` K Prateek Nayak
2025-07-02 11:49 ` [PATCH v2 02/12] sched/deadline: Less agressive dl_server handling Peter Zijlstra
2025-07-02 16:12 ` Juri Lelli
2025-07-10 12:46 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2025-07-14 22:56 ` [PATCH v2 02/12] " Mel Gorman
2025-07-15 14:55 ` Chris Mason
2025-07-16 18:19 ` Mel Gorman
2025-07-30 9:34 ` Geert Uytterhoeven
2025-07-30 9:46 ` Juri Lelli
2025-07-30 10:05 ` Geert Uytterhoeven
2025-08-05 22:03 ` Chris Bainbridge
2025-08-05 23:04 ` Chris Bainbridge
2025-09-15 22:29 ` John Stultz
2025-09-16 4:18 ` John Stultz
2025-09-16 5:28 ` [RFC][PATCH] sched/deadline: Fix dl_server getting stuck, allowing cpu starvation John Stultz
2025-09-16 8:51 ` Juri Lelli
2025-09-16 11:01 ` Peter Zijlstra
2025-09-16 12:52 ` Juri Lelli
2025-09-16 14:30 ` Peter Zijlstra
2025-09-16 17:35 ` John Stultz
2025-09-16 21:30 ` Peter Zijlstra
2025-09-17 3:29 ` John Stultz
2025-09-17 9:34 ` Peter Zijlstra
2025-09-17 12:26 ` Peter Zijlstra
2025-09-17 13:56 ` Juri Lelli
2025-09-17 17:30 ` Peter Zijlstra
2025-09-18 8:37 ` Juri Lelli
2025-09-18 9:04 ` Peter Zijlstra
2025-09-18 9:42 ` Juri Lelli
2025-09-17 19:29 ` John Stultz
2025-09-18 6:56 ` [tip: sched/urgent] sched/deadline: Fix dl_server behaviour tip-bot2 for Peter Zijlstra
2025-09-25 7:55 ` tip-bot2 for Peter Zijlstra
2025-09-18 6:56 ` [tip: sched/urgent] sched/deadline: Fix dl_server getting stuck tip-bot2 for Peter Zijlstra
2025-09-18 14:46 ` Dietmar Eggemann
[not found] ` <CGME20250922215704eucas1p1f53a65a5cd1eafd3e0db006653231efd@eucas1p1.samsung.com>
2025-09-22 21:57 ` Marek Szyprowski
2025-09-22 23:46 ` John Stultz
2025-09-23 6:31 ` Marek Szyprowski
2025-09-23 7:25 ` Peter Zijlstra
2025-09-23 7:52 ` Marek Szyprowski
2025-09-23 22:02 ` Peter Zijlstra
2025-09-29 15:19 ` Marek Szyprowski
[not found] ` <eae77bd0-d874-4ddf-88d7-c1ab75358f91@samsung.com>
2025-10-09 8:35 ` Krzysztof Kozlowski
2025-10-09 9:26 ` Peter Zijlstra [this message]
2025-10-09 11:42 ` Marek Szyprowski
2025-09-25 7:55 ` tip-bot2 for Peter Zijlstra
2025-07-02 11:49 ` [PATCH v2 03/12] sched: Optimize ttwu() / select_task_rq() Peter Zijlstra
2025-07-10 16:47 ` Vincent Guittot
2025-07-14 22:59 ` Mel Gorman
2025-07-02 11:49 ` [PATCH v2 04/12] sched: Use lock guard in ttwu_runnable() Peter Zijlstra
2025-07-10 16:48 ` Vincent Guittot
2025-07-14 23:00 ` Mel Gorman
2025-07-02 11:49 ` [PATCH v2 05/12] sched: Add ttwu_queue controls Peter Zijlstra
2025-07-10 16:51 ` Vincent Guittot
2025-07-14 23:14 ` Mel Gorman
2025-07-02 11:49 ` [PATCH v2 06/12] sched: Introduce ttwu_do_migrate() Peter Zijlstra
2025-07-10 16:51 ` Vincent Guittot
2025-07-02 11:49 ` [PATCH v2 07/12] psi: Split psi_ttwu_dequeue() Peter Zijlstra
2025-07-17 23:59 ` Chris Mason
2025-07-18 18:02 ` Steven Rostedt
2025-07-02 11:49 ` [PATCH v2 08/12] sched: Re-arrange __ttwu_queue_wakelist() Peter Zijlstra
2025-07-02 11:49 ` [PATCH v2 09/12] sched: Clean up ttwu comments Peter Zijlstra
2025-07-02 11:49 ` [PATCH v2 10/12] sched: Use lock guard in sched_ttwu_pending() Peter Zijlstra
2025-07-10 16:51 ` Vincent Guittot
2025-07-02 11:49 ` [PATCH v2 11/12] sched: Change ttwu_runnable() vs sched_delayed Peter Zijlstra
2025-07-02 11:49 ` [PATCH v2 12/12] sched: Add ttwu_queue support for delayed tasks Peter Zijlstra
2025-07-03 16:00 ` Phil Auld
2025-07-03 16:47 ` Peter Zijlstra
2025-07-03 17:11 ` Phil Auld
2025-07-14 13:57 ` Phil Auld
2025-07-04 6:13 ` K Prateek Nayak
2025-07-04 7:59 ` Peter Zijlstra
2025-07-08 12:44 ` Dietmar Eggemann
2025-07-08 18:57 ` Peter Zijlstra
2025-07-08 21:02 ` Peter Zijlstra
2025-07-23 5:42 ` Shrikanth Hegde
2025-07-02 15:27 ` [PATCH v2 00/12] sched: Address schbench regression Chris Mason
2025-07-07 9:05 ` Shrikanth Hegde
2025-07-07 9:11 ` Peter Zijlstra
2025-07-07 9:38 ` Shrikanth Hegde
2025-07-16 13:46 ` Phil Auld
2025-07-17 17:25 ` Phil Auld
2025-07-07 18:19 ` Shrikanth Hegde
2025-07-08 19:02 ` Peter Zijlstra
2025-07-09 16:46 ` Shrikanth Hegde
2025-07-14 17:54 ` Shrikanth Hegde
2025-07-21 19:37 ` Shrikanth Hegde
2025-07-22 20:20 ` Chris Mason
2025-07-24 18:23 ` Chris Mason
2025-07-08 15:09 ` Chris Mason
2025-07-08 17:29 ` Shrikanth Hegde
2025-07-17 13:04 ` Beata Michalska
2025-07-17 16:57 ` Beata Michalska
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