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Thu, 22 Aug 2024 10:43:35 -0700 (PDT) From: Celeste Liu X-Google-Original-From: Celeste Liu Date: Fri, 23 Aug 2024 01:43:26 +0800 Subject: [PATCH v2 1/4] riscv: defconfig: drop RT_GROUP_SCHED=y 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: <20240823-fix-riscv-rt_group_sched-v2-1-e4dbae24f7e1@gmail.com> References: <20240823-fix-riscv-rt_group_sched-v2-0-e4dbae24f7e1@gmail.com> In-Reply-To: <20240823-fix-riscv-rt_group_sched-v2-0-e4dbae24f7e1@gmail.com> 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 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 0.14.1 X-Developer-Signature: v=1; a=openpgp-sha256; l=1885; i=CoelacanthusHex@gmail.com; h=from:subject:message-id; bh=zrg/IlnMUyssz1StuHquhO16krnEeXCPcrxCVtormZo=; b=owJ4nJvAy8zAJfY4pvNJRPo6U8bTakkMaccrDj6cdSh5rvkhA43VF5ie/BGZ8aZM6IH+r8Sia u1NErnCStc6SlkYxLgYZMUUWcR2Pn29rPTRh2W8JjNg5rAygQxh4OIUgIkEJTP8j35R0LfbpvUd 1xaRRpYmh5N3lf8sPhhZfaL89dFXV1JWzmZkmLBztbxRUUjEvrpX0xSd53Jw9lcJmBeKL5h0U7r m3345dgD+6E2g X-Developer-Key: i=CoelacanthusHex@gmail.com; a=openpgp; fpr=892EBC7DC392DFF9C9C03F1D15F4180E73787863 Commit ba6cfef057e1 ("riscv: enable Docker requirements in defconfig") introduced it because of Docker, but Docker has removed this requirement since [1] (2023-04-19). 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.[2] 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.[3] [1]: https://github.com/moby/moby/commit/005150ed69c540fb0b5323e0f2208608c1= 204536 [2]: https://bugzilla.redhat.com/show_bug.cgi?id=3D1229700 [3]: https://github.com/systemd/systemd/issues/13781#issuecomment-549164383 Fixes: ba6cfef057e1 ("riscv: enable Docker requirements in defconfig") Signed-off-by: Celeste Liu Acked-by: Heinrich Schuchardt --- arch/riscv/configs/defconfig | 1 - 1 file changed, 1 deletion(-) diff --git a/arch/riscv/configs/defconfig b/arch/riscv/configs/defconfig index 12dc8c73a8ac..de85c3ab261e 100644 --- a/arch/riscv/configs/defconfig +++ b/arch/riscv/configs/defconfig @@ -9,7 +9,6 @@ CONFIG_CGROUPS=3Dy CONFIG_MEMCG=3Dy CONFIG_CGROUP_SCHED=3Dy CONFIG_CFS_BANDWIDTH=3Dy -CONFIG_RT_GROUP_SCHED=3Dy CONFIG_CGROUP_PIDS=3Dy CONFIG_CGROUP_FREEZER=3Dy CONFIG_CGROUP_HUGETLB=3Dy --=20 2.46.0