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Tue, 14 Jan 2025 15:42:02 -0500 (EST) From: Celeste Liu Date: Wed, 15 Jan 2025 04:41:20 +0800 Subject: [PATCH v4 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: <20250115-fix-riscv-rt_group_sched-v4-1-607606fe73a5@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, Charlie Jenkins , Celeste Liu X-Mailer: b4 0.15-dev X-Developer-Signature: v=1; a=openpgp-sha256; l=1987; i=uwu@coelacanthus.name; h=from:subject:message-id; bh=WkvIObUchYpAilmJK89a2+ds4ehlRbbV+Uqcck4hmYI=; b=owJ4nJvAy8zAJeafov85RWVtBeNptSSG9LYz7JZzu3m/esxYasXrc/3aJMUnP55MOzQjsTiBq Seg9WqipkpHKQuDGBeDrJgiS14Jy0/OS2e793Zs74KZw8oEMoSBi1MAJpLfz/BXtuPp5Qf6PQtd TGe9Tzi5LWZZ3vVca522z6+Y+d6kPv8RyMjw+ofpP9fk2b+37mTferiEddNnkwnxn94lXNFfr20 fd2kKMwBcoU0m X-Developer-Key: i=uwu@coelacanthus.name; 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 Acked-by: Heinrich Schuchardt Acked-by: Charlie Jenkins Signed-off-by: Celeste Liu --- arch/riscv/configs/defconfig | 1 - 1 file changed, 1 deletion(-) diff --git a/arch/riscv/configs/defconfig b/arch/riscv/configs/defconfig index b4a37345703eb35757419aa5a2b057c82ed22fda..46b8fb30726858a945a24097773= 174961c2f4d10 100644 --- a/arch/riscv/configs/defconfig +++ b/arch/riscv/configs/defconfig @@ -10,7 +10,6 @@ CONFIG_MEMCG=3Dy CONFIG_BLK_CGROUP=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 2.48.0 From nobody Mon Dec 15 21:45:49 2025 Received: from fhigh-b5-smtp.messagingengine.com (fhigh-b5-smtp.messagingengine.com [202.12.124.156]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E49F220CCEB; 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Tue, 14 Jan 2025 15:42:09 -0500 (EST) From: Celeste Liu Date: Wed, 15 Jan 2025 04:41:21 +0800 Subject: [PATCH v4 2/4] loongarch: 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: <20250115-fix-riscv-rt_group_sched-v4-2-607606fe73a5@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, Xi Ruoyao , Celeste Liu X-Mailer: b4 0.15-dev X-Developer-Signature: v=1; a=openpgp-sha256; l=1728; i=uwu@coelacanthus.name; h=from:subject:message-id; bh=faYQjbUe+IZ6IbLVoFWLES94wJ4yKdbIyLHK1P3reTU=; b=owJ4nJvAy8zAJeafov85RWVtBeNptSSG9LYzHNpGz3RdNkcq+138urdnco6HmLJOMKeQx8/dB x+9M/n57GhHKQuDGBeDrJgiS14Jy0/OS2e793Zs74KZw8oEMoSBi1MAJnIth5HhTFFkrOksz5Be jqCyI7OyWK2EubUnagjfyV8kYSe7ROMtw3+f+83SDSq+R6Y+//vmimFTUov/35ffOJ3jLvsv+PF vwT8+AA0oSNQ= 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 Reviewed-by: Xi Ruoyao Signed-off-by: Celeste Liu --- arch/loongarch/configs/loongson3_defconfig | 1 - 1 file changed, 1 deletion(-) diff --git a/arch/loongarch/configs/loongson3_defconfig b/arch/loongarch/co= nfigs/loongson3_defconfig index 4dffc90192f7816074c3bd4b55c12159d5757676..4387bcec8f484173e5367456a69= f6a7f03595d46 100644 --- a/arch/loongarch/configs/loongson3_defconfig +++ b/arch/loongarch/configs/loongson3_defconfig @@ -24,7 +24,6 @@ CONFIG_NUMA_BALANCING=3Dy CONFIG_MEMCG=3Dy CONFIG_BLK_CGROUP=3Dy CONFIG_CFS_BANDWIDTH=3Dy -CONFIG_RT_GROUP_SCHED=3Dy CONFIG_CGROUP_PIDS=3Dy CONFIG_CGROUP_RDMA=3Dy CONFIG_CGROUP_FREEZER=3Dy --=20 2.48.0 From nobody Mon Dec 15 21:45:49 2025 Received: from fout-b6-smtp.messagingengine.com (fout-b6-smtp.messagingengine.com [202.12.124.149]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8148F212B34; 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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 From nobody Mon Dec 15 21:45:49 2025 Received: from fhigh-b5-smtp.messagingengine.com (fhigh-b5-smtp.messagingengine.com [202.12.124.156]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 87A2C20DD79; 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Tue, 14 Jan 2025 15:42:20 -0500 (EST) From: Celeste Liu Date: Wed, 15 Jan 2025 04:41:23 +0800 Subject: [PATCH v4 4/4] arm: defconfig: drop RT_GROUP_SCHED=y from bcm2835/tegra/omap2plus 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-v4-4-607606fe73a5@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, Stefan Wahren , Thierry Reding , Celeste Liu X-Mailer: b4 0.15-dev X-Developer-Signature: v=1; a=openpgp-sha256; l=3034; i=uwu@coelacanthus.name; h=from:subject:message-id; bh=FD1/1Qa4M60bWS/VL5WGmaGZ5+Z9xkiSLJsG1Uy3KWw=; b=owJ4nJvAy8zAJeafov85RWVtBeNptSSG9LYzXHLFi27K+J2ZHz412+f0Dang54s+PZiXrRvfZ Mzq7eFZld5RysIgxsUgK6bIklfC8pPz0tnuvR3bu2DmsDKBDGHg4hSAiZwKYPgftqP47j7Xd8HJ nxstvriK7bd9n/3oW4KK9qknWza/vBH1hOF/NJsix3WlLcsedN04JFMQH3F0/rRIpYj0J/MeWk4 6tv8qCwAph01E X-Developer-Key: i=uwu@coelacanthus.name; a=openpgp; fpr=892EBC7DC392DFF9C9C03F1D15F4180E73787863 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 Tested-by: Stefan Wahren Acked-by: Kevin Hilman Acked-by: Thierry Reding Signed-off-by: Celeste Liu Acked-by: Florian Fainelli #=20 --- 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 b5f0bd8dd536990a0726e73a6855d25c1286a768..27dc3bf6b124c2012b7a1a768f2= f900f49903cd1 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 3a166c2f02bd80634fee3bd8c4579fdbad84ccfa..9cb265c8d4144ea9a41f02640db= c8a06b710323b 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 d2a094ad360cefefbc3bd35226c5d23eadce42c1..3a9bda2bf422b14085c60b39a2c= 3df86fe0994bb 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 2.48.0