linux-kernel - Linux warns `sched: DL replenish lagged too much`

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Message-ID: <6ebe1130-0143-4388-9d69-ead0bf1fddf9@molgen.mpg.de>
Date: Thu, 20 Feb 2025 11:47:14 +0100
From: Paul Menzel <pmenzel@...gen.mpg.de>
To: Ingo Molnar <mingo@...hat.com>, Peter Zijlstra <peterz@...radead.org>,
 Juri Lelli <juri.lelli@...hat.com>,
 Vincent Guittot <vincent.guittot@...aro.org>
Cc: LKML <linux-kernel@...r.kernel.org>
Subject: Linux warns `sched: DL replenish lagged too much`

Dear Linux folks,

On the Intel Kaby Lake laptop Dell XPS 13 with Linux 
6.14.0-rc3-00060-g6537cfb395f3, waking it up from ACPI S3 with an LMP 
USB-C mini dock connected, that had an Ethernet cable and a power 
adapter plugged in, everything was lagging, and also the video in the 
opened Firefox Nightly browser lagged quite a bit. This has happened in 
the past, but not that bad and long. Today for the first time, Linux 
logged the warning below:

     sched: DL replenish lagged too much

(This is from `kernel/sched/deadline.c`.)

I have no idea, if it’s related to the hardware itself, that causes it 
to lag, that a suspend/resume cycle fixes, or if it’s related to the 
USB-C controller that has bugs in that early generation, or if it’s 
related to GNOME/Mutter (*mutter-common* 48~beta-3) or Firefox or the 
Web video player used by the site.

As often the case with this, I have no way to reliably reproduce it, and 
in this case to reproduce the warning. I can only say, that this warning 
has not been logged in the available log files since September 2024. 
Linux “6.11-rc0” was used then. Please find the log messages attached.

In case this information is not useful, should this happen again, it’d 
be great if you could suggest what and how I should collect debugging 
information next time.

Kind regards,

Paul
View attachment "20250220--dell-xps-13-9360--linux-6.14-rc3-00060-g6537cfb395f3.txt" of type "text/plain" (509174 bytes)