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Mon, 20 Oct 2025 02:40:25 -0700 (PDT) X-Google-Smtp-Source: AGHT+IGK8F+GqQ8zW3Xhikabz/d5iU4X0cDrsMvQLTZk1Wk95dGjkhJCo9kNuH9KNgoV+qjD8ThxQg== X-Received: by 2002:a05:600c:858c:b0:46d:b665:1d95 with SMTP id 5b1f17b1804b1-47117917bb6mr82566535e9.32.1760953225218; Mon, 20 Oct 2025 02:40:25 -0700 (PDT) Received: from jlelli-thinkpadt14gen4.remote.csb ([176.206.13.103]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-47152959b55sm140662125e9.6.2025.10.20.02.40.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 20 Oct 2025 02:40:24 -0700 (PDT) Date: Mon, 20 Oct 2025 11:40:22 +0200 From: Juri Lelli To: Yuri Andriaccio Cc: Ingo Molnar , Peter Zijlstra , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , linux-kernel@vger.kernel.org, Luca Abeni , Yuri Andriaccio Subject: Re: [RFC PATCH v3 00/24] Hierarchical Constant Bandwidth Server Message-ID: References: <20250929092221.10947-1-yurand2000@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On 02/10/25 10:00, Juri Lelli wrote: > Hello! > > On 29/09/25 11:21, Yuri Andriaccio wrote: > > Hello, > > > > This is the v3 for Hierarchical Constant Bandwidth Server, aiming at replacing > > the current RT_GROUP_SCHED mechanism with something more robust and > > theoretically sound. The patchset has been presented at OSPM25 > > (https://retis.sssup.it/ospm-summit/), and a summary of its inner workings can > > be found at https://lwn.net/Articles/1021332/ . You can find the previous > > versions of this patchset at the bottom of the page, in particular version 1 > > which talks in more detail what this patchset is all about and how it is > > implemented. > > > > This v3 version further reworks some of the patches as suggested by Juri Lelli. > > While most of the work is refactorings, the following were also changed: > > - The first patch which removed fair-servers' bandwidth accounting has been > > removed, as it was deemed wrong. You can find the last version of this removed > > patch, just for history reasons, here: > > https://lore.kernel.org/all/20250903114448.664452-1-yurand2000@gmail.com/ > > Peter wasn't indeed happy with that patch, but I am not sure we finished > that discussion. Both myself and Luca had further objections to what > Peter said, but not further replies after (which can very well be a sign > that he is still adamnt in saying no go away :). Peter? > > https://lore.kernel.org/lkml/aLk9BNnFYZ3bhVAE@jlelli-thinkpadt14gen4.remote.csb/ > https://lore.kernel.org/lkml/20250904091217.78de3dde@luca64/ I had a quick chat with Peter on IRC about this. We now seem to agree that a third option would be to move to explicitly account dl-server(s), correspondingly moving from a 95% to 100% limit. That would also make our life easier in the future with additional dl-servers (e.g. scx-server). What do you think?