From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 465C4C3271E for ; Mon, 8 Jul 2024 23:49:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Type:MIME-Version: Message-ID:Date:References:In-Reply-To:Subject:Cc:To:From:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=KTCvURDHt1Ehhy2ogJ4G2eNRAbN+TU2XGb1d5J/SBYc=; b=lUQHzl3d9qvKr1Gik/y9NZgO2d LUt+mlYkWe8W2yljc6JzuvvUqbZb1CG5ANR5oGFoo6Z1TAfPq/FCIlZnJMdp/oI6EVohwZOw2Fv5K pZCJTXoz+HFOeQogxNEGxSFpJHMcXIBZAOIXKTWrxVWkJkQVReI+AUhKy6E/6rnxCeAmQ2EWRok4h Kl5ujMTN0+ie7Y67acp9VFnMKtpOP/9b80QAAU2i17MaqiFjbRsg1AD923ACVeeMzSGdOMrS+qha/ go04niZ4iULV7IxAV2jeG9iG7exNL82/LCKzbRxQZrLN/OmQU1QWcZIXgJkQGm4ixaRhraJC3xYjD l2ZIjDZQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sQy6i-00000005MFQ-3P2P; Mon, 08 Jul 2024 23:49:20 +0000 Received: from mail-pj1-f48.google.com ([209.85.216.48]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1sQy6S-00000005MBV-2qeK for linux-arm-kernel@lists.infradead.org; Mon, 08 Jul 2024 23:49:06 +0000 Received: by mail-pj1-f48.google.com with SMTP id 98e67ed59e1d1-2c98660fc91so2599032a91.1 for ; Mon, 08 Jul 2024 16:49:03 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1720482543; x=1721087343; h=mime-version:message-id:date:references:in-reply-to:subject:cc:to :from:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=KTCvURDHt1Ehhy2ogJ4G2eNRAbN+TU2XGb1d5J/SBYc=; b=PGHEJUqjU7yuec6r1Dw9bVLSOubZ2+zPmAQiG1RU1a8jjr0cL9oehHQXCXw6H3+Sc2 PauK9rZvsIIxtIU7xWSlixv56XXxnXREhVIyUY+Ju75PDayxhlDKywHh4rteGmNCYBZ/ 6HWPRyduRkOLu0ipP/3QUG5QCoCRgqyHnz2OPz7+VYX6qQwbZRQjs1ErCxYhsOeVrTq2 EmbQKLdFeYStSOZJzfdCi+sD7KqkMCCPGqKW2+kfAOE9GjXJZHOjwzN7QNdhXhkDzdZH RuW+HWuGKNkQPQWHkbVCgzMhgxGPwjCRt7+P61Ng+hPOROh2pNl5soZaY+Gb0QO15Qj4 BEQA== X-Forwarded-Encrypted: i=1; AJvYcCVTKaJjPWhY+DlSxtFpcpX5kCiWtyezogCpEsxd+zrDGfEvmk53A4hWjGHtiZmR/Sow01QWkw5EvB6gVR+bWT+6iwQSAu+qzPPufdIrnC7stuf/DyU= X-Gm-Message-State: AOJu0Yz+N2WgqE+3RJDZTfB4Jqd4nSEoAEr2FrZivT9B6fpSSWjmObPI LDob16vgMi5R6dHCfDZIWiclR2I9yqTFx0DBB4ekVp/VVfv6ZiD/+XLxc9aiXPg= X-Google-Smtp-Source: AGHT+IF2sRCcp1Qt2ncA7/dcBS7eQVYhbuVP4CESqTDlDqz8AWSIBYQ0ftySS6HXoODFEfyN2bXeTQ== X-Received: by 2002:a17:90a:a10d:b0:2c4:dfa6:df00 with SMTP id 98e67ed59e1d1-2ca35be0661mr981011a91.8.1720482542878; Mon, 08 Jul 2024 16:49:02 -0700 (PDT) Received: from localhost (97-126-77-189.tukw.qwest.net. [97.126.77.189]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-2ca344c399csm596679a91.5.2024.07.08.16.49.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 08 Jul 2024 16:49:02 -0700 (PDT) From: Kevin Hilman To: Celeste Liu , Heinrich Schuchardt , Anup Patel , Guo Ren , Palmer Dabbelt , Paul Walmsley , Huacai Chen , WANG Xuerui , Thomas Bogendoerfer , Vladimir Kondratiev , Gregory CLEMENT , =?utf-8?Q?Th=C3=A9o?= Lebrun , Michael Ellerman , Nicholas Piggin , Christophe Leroy , "Naveen N . Rao" , Sven Joachim , Yoshinori Sato , Rich Felker , John Paul Adrian Glaubitz , Russell King , Florian Fainelli , Ray Jui , Scott Branden , Broadcom internal kernel review list , Tony Lindgren , Thierry Reding , Jonathan Hunter , Arnd Bergmann , Mykola Lysenko , linux-riscv@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-rpi-kernel@lists.infradead.org, linux-omap@vger.kernel.org, linux-tegra@vger.kernel.org, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-sh@vger.kernel.org Cc: linux-kselftest@vger.kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, Lennart Poettering , Icenowy Zheng , Celeste Liu Subject: Re: [PATCH 6/6] arm: defconfig: drop RT_GROUP_SCHED=y from bcm2855/tegra/omap2plus In-Reply-To: <20240530111947.549474-14-CoelacanthusHex@gmail.com> References: <20240530111947.549474-8-CoelacanthusHex@gmail.com> <20240530111947.549474-14-CoelacanthusHex@gmail.com> Date: Mon, 08 Jul 2024 16:49:01 -0700 Message-ID: <7hv81f78cy.fsf@baylibre.com> MIME-Version: 1.0 Content-Type: text/plain X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240708_164904_747185_B236E242 X-CRM114-Status: GOOD ( 16.02 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Celeste Liu writes: > Commit 673ce00c5d6c ("ARM: omap2plus_defconfig: Add support for distros > with systemd") said it's because of recommendation from systemd. But > systemd changed their recommendation later.[1] > > For cgroup v1, if turned on, and there's any cgroup in the "cpu" hierarchy it > needs an RT budget assigned, otherwise the processes in it will not be able to > get RT at all. The problem with RT group scheduling is that it requires the > budget assigned but there's no way we could assign a default budget, since the > values to assign are both upper and lower time limits, are absolute, and need to > be sum up to < 1 for each individal cgroup. That means we cannot really come up > with values that would work by default in the general case.[2] > > For cgroup v2, it's almost unusable as well. If it turned on, the cpu controller > can only be enabled when all RT processes are in the root cgroup. But it will > lose the benefits of cgroup v2 if all RT process were placed in the same cgroup. > > Red Hat, Gentoo, Arch Linux and Debian all disable it. systemd also doesn't > support it. > > [1]: https://github.com/systemd/systemd/commit/f4e74be1856b3ac058acbf1be321c31d5299f69f > [2]: https://bugzilla.redhat.com/show_bug.cgi?id=1229700 > > Signed-off-by: Celeste Liu > --- > arch/arm/configs/bcm2835_defconfig | 1 - > arch/arm/configs/omap2plus_defconfig | 1 - > arch/arm/configs/tegra_defconfig | 1 - For omap2plus_defconfig: Acked-by: Kevin Hilman