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Thu, 12 Nov 2026 07:01:10 -0800 (PST) X-Received: by 2002:a05:600c:6819:b0:4a2:167a:c946 with SMTP id 5b1f17b1804b1-4ba0935f880mr100717275e9.13.1794495670509; Thu, 12 Nov 2026 07:01:10 -0800 (PST) Received: from jlelli-thinkpadt14gen4.remote.csb ([151.29.158.90]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4ba08ddd467sm110908625e9.0.2026.11.12.07.01.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 12 Nov 2026 07:01:09 -0800 (PST) Date: Thu, 12 Nov 2026 16:01:06 +0100 From: Juri Lelli To: "Paul E. McKenney" Cc: Sebastian Andrzej Siewior , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, rcu@vger.kernel.org, linux-doc@vger.kernel.org, John Ogness , Jonathan Corbet , Shuah Khan , Randy Dunlap , Ingo Molnar , Peter Zijlstra , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , K Prateek Nayak , luca abeni , Yuri Andriaccio , Yuri Andriaccio , Frederic Weisbecker , Neeraj Upadhyay , Joel Fernandes , Josh Triplett , Boqun Feng , Uladzislau Rezki , Mathieu Desnoyers , Lai Jiangshan , Zqiang , Davidlohr Bueso , Tejun Heo , Johannes Weiner , Michal =?iso-8859-1?Q?Koutn=FD?= , Qais Yousef Subject: Re: [PATCH v2 0/7] sched: RT throttling cleanup and a bit of documentation Message-ID: References: <20261110-sched_dl-v2-0-cc9399f7aeb1@linutronix.de> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Hello, On 10/11/26 11:56, Paul E. McKenney wrote: > On Tue, Nov 10, 2026 at 06:34:42PM +0100, Sebastian Andrzej Siewior wrote: > > People used to disable the RT throttling mechanism by writing -1 to > > /proc/sys/kernel/sched_rt_runtime_us. Since v6.12 they can still do this > > but they don't disable RT throttling anymore. Instead this throttling > > mechanism has been taken over by the fair_server which can be configured > > via debugfs. > > This is not really documented by a hint appeared a few cycles later in > > Documentation/scheduler/sched-rt-group.rst. This can be found once you > > know what you are looking for because this document describes the RT > > group scheduling (CONFIG_RT_GROUP_SCHED). The fair_server is used even > > without it. > > The then there is global DL resource control which also shares this > > file proc file (which is stuck if CONFIG_RT_GROUP_SCHED is enabled). > > Nice, thank you! > > Unfortunately but unsurprisingly, this gets the same divide-by-zero > issue reported (belatedly) on the earlier series: > > https://lore.kernel.org/all/e58e48c3-ac62-40cd-b5d3-2de87db12496@paulmck-laptop/ > I wonder if this fixes is https://lore.kernel.org/lkml/20261108185406.1549770-6-mathieu.desnoyers@efficios.com/ Thanks, Juri