From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from xry111.site (xry111.site [89.208.246.23]) (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 61D97174EC3; Thu, 30 May 2024 11:27:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=89.208.246.23 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717068478; cv=none; b=SBJZZkblDM0t/6FV93OLDAY98SR1WSNRp16ClpITDXg9XaCooN6T9IjoGdi9dhNrTl0CYGsUUo7bxAjjY9ITPaUhMvgqzjqe093TspzUnaiNst2TSV55rD+JrJwogbNhlCEfkGMbWKseLyZT7syC34znoNjFh6kxmA5gub0bpDE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717068478; c=relaxed/simple; bh=QKCYv/9pkeewZS0wdLDjidR9iHNKpRPbnM/6kemvOTo=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=WxXhFvMtMjgVSzLpEp6TKhWoHVAJaB06pdJAhbGEJ9zqqfLQNc2QwR9nX3j4IXcpoKixFqCttojsYf0cuLYJ5q0pjYELEFSiIuRWNcpk8vpMWVlrtLF1h0L2vk7igPSIdiTnqmxZxx2fLTzJtXhfIIhQcLUB0wtBuPdqBk22Csk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=xry111.site; spf=pass smtp.mailfrom=xry111.site; dkim=pass (1024-bit key) header.d=xry111.site header.i=@xry111.site header.b=FpZS537T; arc=none smtp.client-ip=89.208.246.23 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=xry111.site Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=xry111.site Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=xry111.site header.i=@xry111.site header.b="FpZS537T" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=xry111.site; s=default; t=1717068464; bh=QKCYv/9pkeewZS0wdLDjidR9iHNKpRPbnM/6kemvOTo=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=FpZS537T3yPjs0iXwLB6GlRYL0cdPMhC1/wShIU0j7i47Zz9Tq4aKnr7A8nrfwGme 9lzOUhjVJGLOLZqyiXFOMnX8rKmDEv+3qt3eMOkee7hOiQVhkl2PN7zQ51r+NWqHBV R1iDpMCyTvvksWQ0oQYf3mlL90Er9AtaOI0Fdkps= Received: from [127.0.0.1] (unknown [IPv6:2001:470:683e::1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature ECDSA (P-384) server-digest SHA384) (Client did not present a certificate) (Authenticated sender: xry111@xry111.site) by xry111.site (Postfix) with ESMTPSA id 998376770C; Thu, 30 May 2024 07:27:34 -0400 (EDT) Message-ID: <19dd3ba543ee3796afd4ee75daea199f56f32bcb.camel@xry111.site> Subject: Re: [PATCH 2/6] loongarch: defconfig: drop RT_GROUP_SCHED=y From: Xi Ruoyao To: Celeste Liu , Heinrich Schuchardt , Anup Patel , Guo Ren , Palmer Dabbelt , Paul Walmsley , Huacai Chen , WANG Xuerui , Thomas Bogendoerfer , Vladimir Kondratiev , Gregory CLEMENT , =?ISO-8859-1?Q?Th=E9o?= 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 Date: Thu, 30 May 2024 19:27:32 +0800 In-Reply-To: <20240530111947.549474-10-CoelacanthusHex@gmail.com> References: <20240530111947.549474-8-CoelacanthusHex@gmail.com> <20240530111947.549474-10-CoelacanthusHex@gmail.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.52.2 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Thu, 2024-05-30 at 19:19 +0800, Celeste Liu wrote: > For cgroup v1, if turned on, and there's any cgroup in the "cpu" hierarch= y it > needs an RT budget assigned, otherwise the processes in it will not be ab= le to > get RT at all. The problem with RT group scheduling is that it requires t= he > budget assigned but there's no way we could assign a default budget, sinc= e 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 c= ome up > with values that would work by default in the general case.[1] >=20 > For cgroup v2, it's almost unusable as well. If it turned on, the cpu con= troller > 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. >=20 > Red Hat, Gentoo, Arch Linux and Debian all disable it. systemd also doesn= 't > support it.[2] >=20 > [1]: https://bugzilla.redhat.com/show_bug.cgi?id=3D1229700 > [2]: https://github.com/systemd/systemd/issues/13781#issuecomment-5491643= 83 >=20 > Signed-off-by: Celeste Liu As a distro maintainer who had once been bitten by this option: Reviewed-by: Xi Ruoyao > --- > =C2=A0arch/loongarch/configs/loongson3_defconfig | 1 - > =C2=A01 file changed, 1 deletion(-) >=20 > diff --git a/arch/loongarch/configs/loongson3_defconfig b/arch/loongarch/= configs/loongson3_defconfig > index b4252c357c8e..4d93adb3f1a2 100644 > --- a/arch/loongarch/configs/loongson3_defconfig > +++ b/arch/loongarch/configs/loongson3_defconfig > @@ -23,7 +23,6 @@ CONFIG_NUMA_BALANCING=3Dy > =C2=A0CONFIG_MEMCG=3Dy > =C2=A0CONFIG_BLK_CGROUP=3Dy > =C2=A0CONFIG_CFS_BANDWIDTH=3Dy > -CONFIG_RT_GROUP_SCHED=3Dy > =C2=A0CONFIG_CGROUP_PIDS=3Dy > =C2=A0CONFIG_CGROUP_RDMA=3Dy > =C2=A0CONFIG_CGROUP_FREEZER=3Dy --=20 Xi Ruoyao School of Aerospace Science and Technology, Xidian University