linux-kernel - Re: [RFC PATCH v2 18/25] sched/rt: Zero rt-cgroups default bandwidth

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <aJ3vBA_PmsaGSYUj@jlelli-thinkpadt14gen4.remote.csb>
Date: Thu, 14 Aug 2025 16:13:24 +0200
From: Juri Lelli <juri.lelli@...hat.com>
To: Yuri Andriaccio <yurand2000@...il.com>
Cc: Ingo Molnar <mingo@...hat.com>, Peter Zijlstra <peterz@...radead.org>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Dietmar Eggemann <dietmar.eggemann@....com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
	Valentin Schneider <vschneid@...hat.com>,
	linux-kernel@...r.kernel.org,
	Luca Abeni <luca.abeni@...tannapisa.it>,
	Yuri Andriaccio <yuri.andriaccio@...tannapisa.it>
Subject: Re: [RFC PATCH v2 18/25] sched/rt: Zero rt-cgroups default bandwidth

Hi!

On 31/07/25 12:55, Yuri Andriaccio wrote:
> Set the default rt-cgroups runtime to zero, otherwise a cgroup-v1 kernel will
> not be able to start SCHED_DEADLINE tasks. The bandwidth for rt-cgroups must

Well, we disabled v1 support at this point with the previous patch,
didn't we? :)

> then be manually assigned after the kernel boots.
> 
> Allow zeroing the runtime of the root control group. This runtime only affects
> the available bandwidth of the rt-cgroup hierarchy but not the SCHED_FIFO /
> SCHED_RR tasks on the global runqueue.
> 
> Notes:
> Disabling the root control group bandwidth should not cause any side effect, as
> SCHED_FIFO / SCHED_RR tasks do not depend on it since the introduction of
> fair_servers.

I believe this deserves proper documentation.

Thanks,
Juri