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Tue, 14 Jan 2025 15:42:14 -0500 (EST) From: Celeste Liu Date: Wed, 15 Jan 2025 04:41:22 +0800 Subject: [PATCH v4 3/4] sh: defconfig: drop RT_GROUP_SCHED=y from sdk7786/urquell 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="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20250115-fix-riscv-rt_group_sched-v4-3-607606fe73a5@coelacanthus.name> References: <20250115-fix-riscv-rt_group_sched-v4-0-607606fe73a5@coelacanthus.name> In-Reply-To: <20250115-fix-riscv-rt_group_sched-v4-0-607606fe73a5@coelacanthus.name> To: Paul Walmsley , Palmer Dabbelt , Albert Ou , Guo Ren , Anup Patel , Heinrich Schuchardt , Huacai Chen , WANG Xuerui , Yoshinori Sato , Rich Felker , John Paul Adrian Glaubitz , Russell King , Florian Fainelli , Broadcom internal kernel review list , Ray Jui , Scott Branden , Tony Lindgren , Thierry Reding , Jonathan Hunter , Aaro Koskinen , Andreas Kemnade , Kevin Hilman , Roger Quadros Cc: Palmer Dabbelt , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, loongarch@lists.linux.dev, linux-sh@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-rpi-kernel@lists.infradead.org, linux-omap@vger.kernel.org, linux-tegra@vger.kernel.org, Celeste Liu X-Mailer: b4 0.15-dev X-Developer-Signature: v=1; a=openpgp-sha256; l=2139; i=uwu@coelacanthus.name; h=from:subject:message-id; bh=BhZXBD4LrwRi3kBTuqWLXE3VKHJ0GCDQScQEjxdA+cU=; b=owJ4nJvAy8zAJeafov85RWVtBeNptSSG9LYznD2fd8RwHNpoculb9K0DbSGum9JK0po6eNP3r XvhzbsqR62jlIVBjItBVkyRJa+E5SfnpbPdezu2d8HMYWUCGcLAxSkAE4mXYPjFdGNfLecKz3NZ c/l+va5WTKo7y3prwpVfJ46wr578m4stjOGf0c+3AjpK3ydda3l2lrmxVG7ynlsv1Z/xT9xxwKV oxbfTPACIpk1T X-Developer-Key: i=uwu@coelacanthus.name; a=openpgp; fpr=892EBC7DC392DFF9C9C03F1D15F4180E73787863 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 ne= ed to be sum up to < 1 for each individal cgroup. That means we cannot really com= e up with values that would work by default in the general case.[1] For cgroup v2, it's almost unusable as well. If it turned on, the cpu contr= oller can only be enabled when all RT processes are in the root cgroup. But it wi= ll lose the benefits of cgroup v2 if all RT process were placed in the same cg= roup. Red Hat, Gentoo, Arch Linux and Debian all disable it. systemd also doesn't support it.[2] [1]: https://bugzilla.redhat.com/show_bug.cgi?id=3D1229700 [2]: https://github.com/systemd/systemd/issues/13781#issuecomment-549164383 Signed-off-by: Celeste Liu --- arch/sh/configs/sdk7786_defconfig | 1 - arch/sh/configs/urquell_defconfig | 1 - 2 files changed, 2 deletions(-) diff --git a/arch/sh/configs/sdk7786_defconfig b/arch/sh/configs/sdk7786_de= fconfig index 07894f13441ef622c3af8d8f4b5770c2ab66bcd8..7a6efd5b4a62463381005072a67= 9a8ce022a2ef9 100644 --- a/arch/sh/configs/sdk7786_defconfig +++ b/arch/sh/configs/sdk7786_defconfig @@ -17,7 +17,6 @@ CONFIG_CPUSETS=3Dy CONFIG_CGROUP_CPUACCT=3Dy CONFIG_CGROUP_MEMCG=3Dy CONFIG_CGROUP_SCHED=3Dy -CONFIG_RT_GROUP_SCHED=3Dy CONFIG_BLK_CGROUP=3Dy CONFIG_RELAY=3Dy CONFIG_NAMESPACES=3Dy diff --git a/arch/sh/configs/urquell_defconfig b/arch/sh/configs/urquell_de= fconfig index 00ef62133b04ded8d0b4221f11e0adafde99d386..9cf4a719001ea5ef4b031c1bbbf= 8098e8af5a2b2 100644 --- a/arch/sh/configs/urquell_defconfig +++ b/arch/sh/configs/urquell_defconfig @@ -15,7 +15,6 @@ CONFIG_CPUSETS=3Dy CONFIG_CGROUP_CPUACCT=3Dy CONFIG_CGROUP_MEMCG=3Dy CONFIG_CGROUP_SCHED=3Dy -CONFIG_RT_GROUP_SCHED=3Dy CONFIG_BLK_DEV_INITRD=3Dy CONFIG_PROFILING=3Dy CONFIG_MODULES=3Dy --=20 2.48.0