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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: [PATCH 6/6] arm: defconfig: drop RT_GROUP_SCHED=y from bcm2855/tegra/omap2plus Date: Thu, 30 May 2024 19:19:54 +0800 Message-ID: <20240530111947.549474-14-CoelacanthusHex@gmail.com> X-Mailer: git-send-email 2.45.1 In-Reply-To: <20240530111947.549474-8-CoelacanthusHex@gmail.com> References: <20240530111947.549474-8-CoelacanthusHex@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2729; i=CoelacanthusHex@gmail.com; h=from:subject; bh=z/Xh6Oh4/edMyA0oTGEdVRRBweOMR/LS4ucNKKx8jxk=; b=owJ4nJvAy8zAJfY4pvNJRPo6U8bTakkMaREJt//Jpz1/9vq+ftrjnHPOdUJ7Zl16y3oqfNMJ2 c4TmxeuZVnZUcrCIMbFICumyCK28+nrZaWPPizjNZkBM4eVCWQIAxenAExEIJzhf8HRRdu8P/5W lRSfdEtSzuIjW+AJrhe/BHfb27mxp8vLBjP8D+rcabfgddQ8Botz1wy6Gi5ev2tY0Ppvy/7rzt8 y5t8MZQUAhClPwQ== X-Developer-Key: i=CoelacanthusHex@gmail.com; a=openpgp; fpr=892EBC7DC392DFF9C9C03F1D15F4180E73787863 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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 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. [1]: https://github.com/systemd/systemd/commit/f4e74be1856b3ac058acbf1be321= c31d5299f69f [2]: https://bugzilla.redhat.com/show_bug.cgi?id=3D1229700 Signed-off-by: Celeste Liu Acked-by: Kevin Hilman Tested-by: Stefan Wahren --- arch/arm/configs/bcm2835_defconfig | 1 - arch/arm/configs/omap2plus_defconfig | 1 - arch/arm/configs/tegra_defconfig | 1 - 3 files changed, 3 deletions(-) diff --git a/arch/arm/configs/bcm2835_defconfig b/arch/arm/configs/bcm2835_= defconfig index b5f0bd8dd536..27dc3bf6b124 100644 --- a/arch/arm/configs/bcm2835_defconfig +++ b/arch/arm/configs/bcm2835_defconfig @@ -7,7 +7,6 @@ CONFIG_BSD_PROCESS_ACCT=3Dy CONFIG_BSD_PROCESS_ACCT_V3=3Dy CONFIG_LOG_BUF_SHIFT=3D18 CONFIG_CFS_BANDWIDTH=3Dy -CONFIG_RT_GROUP_SCHED=3Dy CONFIG_CGROUP_FREEZER=3Dy CONFIG_CPUSETS=3Dy CONFIG_CGROUP_DEVICE=3Dy diff --git a/arch/arm/configs/omap2plus_defconfig b/arch/arm/configs/omap2p= lus_defconfig index 3a166c2f02bd..9cb265c8d414 100644 --- a/arch/arm/configs/omap2plus_defconfig +++ b/arch/arm/configs/omap2plus_defconfig @@ -13,7 +13,6 @@ CONFIG_MEMCG=3Dy CONFIG_BLK_CGROUP=3Dy CONFIG_CGROUP_SCHED=3Dy CONFIG_CFS_BANDWIDTH=3Dy -CONFIG_RT_GROUP_SCHED=3Dy CONFIG_CGROUP_FREEZER=3Dy CONFIG_CPUSETS=3Dy CONFIG_CGROUP_DEVICE=3Dy diff --git a/arch/arm/configs/tegra_defconfig b/arch/arm/configs/tegra_defc= onfig index d2a094ad360c..3a9bda2bf422 100644 --- a/arch/arm/configs/tegra_defconfig +++ b/arch/arm/configs/tegra_defconfig @@ -6,7 +6,6 @@ CONFIG_IKCONFIG=3Dy CONFIG_IKCONFIG_PROC=3Dy CONFIG_CGROUPS=3Dy CONFIG_CGROUP_SCHED=3Dy -CONFIG_RT_GROUP_SCHED=3Dy CONFIG_CGROUP_FREEZER=3Dy CONFIG_CGROUP_CPUACCT=3Dy CONFIG_CGROUP_DEBUG=3Dy --=20 2.45.1