From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from esa.microchip.iphmx.com (esa.microchip.iphmx.com [68.232.154.123]) (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 0618F17BB04; Mon, 9 Sep 2024 11:54:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=68.232.154.123 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725882861; cv=none; b=QiZu4ADPv+9Qc5svFOFlfELFjPtImInBPYOwOJOIqTn3LaDmhdNOYcG2ToxTGmusEu8545+uXk4+NSSDTpnvAW+nQkFHdZqAqHhWaSDuGRdhzDqE8GGD/jv/I/Bw9xg0X8Equk5EtmdkmjzOlbTLNVjEpDB2BmahVArK1/teDy4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725882861; c=relaxed/simple; bh=S/0Gvcdwc9czGIGZ/KN+mgXrysiIL6aDrU9W19Ga/ZE=; h=Date:From:To:CC:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=pKbgQJwuBrnARVRUytO8nmmmFrrqLOH3ytIKt/NPBv19JV8SbDktlAVR+7mmtNG3xe2vBJ1QsHZtRqLfaPjTB+lB4hzoN8JSqbXZAYl6u9h77tjXjnQZ5uiX8Ey5zdeeLfXsMKtJesDW0ukYnzw/azxArHqnYVRUwWBIThgn9iY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=microchip.com; spf=pass smtp.mailfrom=microchip.com; dkim=pass (2048-bit key) header.d=microchip.com header.i=@microchip.com header.b=h9w5RVGK; arc=none smtp.client-ip=68.232.154.123 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=microchip.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=microchip.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=microchip.com header.i=@microchip.com header.b="h9w5RVGK" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=microchip.com; i=@microchip.com; q=dns/txt; s=mchp; t=1725882859; x=1757418859; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=S/0Gvcdwc9czGIGZ/KN+mgXrysiIL6aDrU9W19Ga/ZE=; b=h9w5RVGKp8A/YMgL8zgEtbXena/cWIWEdeH9IOGbgGc4KxM5KLuxaAg7 tgx3ImNnN0ZC9eZI9Bhp1hhUrqhJy/S24m69g9qwfOMyRdVvVQEWzz2Zi Oi164IJzZODTJsavTZg27WGHk1UGefXPWmp316CyqhvUo1HBm3wP6Hc2E sIVVv1R1wUWTGoVilrakRujDJu+QzEfYvsQWCC155a++RklOulE68XqMO 3OY77aEwy7tT2yOgVZUdZqZR9nB+up/yu9C6cTf4RDuZCLBvwTtnfF+5s R7DPjzONhYmIN37guh+yfaHeDMn9MmDfJd0sL+v+KV6g2CxaYQPrOAf5y Q==; X-CSE-ConnectionGUID: Ke3+C3CXR++lxv0xXUTyow== X-CSE-MsgGUID: Jln5HjirQm6z9i/EpH+Fiw== X-IronPort-AV: E=Sophos;i="6.10,214,1719903600"; d="asc'?scan'208";a="32144688" X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN Received: from unknown (HELO email.microchip.com) ([170.129.1.10]) by esa2.microchip.iphmx.com with ESMTP/TLS/ECDHE-RSA-AES128-GCM-SHA256; 09 Sep 2024 04:54:17 -0700 Received: from chn-vm-ex02.mchp-main.com (10.10.85.144) by chn-vm-ex01.mchp-main.com (10.10.85.143) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.35; Mon, 9 Sep 2024 04:53:54 -0700 Received: from wendy (10.10.85.11) by chn-vm-ex02.mchp-main.com (10.10.85.144) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.35 via Frontend Transport; Mon, 9 Sep 2024 04:53:50 -0700 Date: Mon, 9 Sep 2024 12:53:17 +0100 From: Conor Dooley To: Celeste Liu CC: 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 , Palmer Dabbelt , , , , , , , , Subject: Re: [PATCH v2 1/4] riscv: defconfig: drop RT_GROUP_SCHED=y Message-ID: <20240909-gave-celtic-af2ea8bc38d5@wendy> References: <20240823-fix-riscv-rt_group_sched-v2-0-e4dbae24f7e1@gmail.com> <20240823-fix-riscv-rt_group_sched-v2-1-e4dbae24f7e1@gmail.com> Precedence: bulk X-Mailing-List: linux-tegra@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="SUs/mhM/C8VTfn2w" Content-Disposition: inline In-Reply-To: <20240823-fix-riscv-rt_group_sched-v2-1-e4dbae24f7e1@gmail.com> --SUs/mhM/C8VTfn2w Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Aug 23, 2024 at 01:43:26AM +0800, Celeste Liu wrote: > Commit ba6cfef057e1 ("riscv: enable Docker requirements in defconfig") > introduced it because of Docker, but Docker has removed this requirement > since [1] (2023-04-19). >=20 > 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.[2] >=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.[3] >=20 > [1]: https://github.com/moby/moby/commit/005150ed69c540fb0b5323e0f2208608= c1204536 > [2]: https://bugzilla.redhat.com/show_bug.cgi?id=3D1229700 > [3]: https://github.com/systemd/systemd/issues/13781#issuecomment-5491643= 83 >=20 > Fixes: ba6cfef057e1 ("riscv: enable Docker requirements in defconfig") I don't think this fixes tag is suitable, the commit you cite in moby/docker is a year younger than the one in the fixes tag, so it was correct at the time it was written. I think the fixes tag should just be removed, since that commit was not wrong. Or am I missing something? > Signed-off-by: Celeste Liu > --- > arch/riscv/configs/defconfig | 1 - > 1 file changed, 1 deletion(-) >=20 > 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 > --=20 > 2.46.0 >=20 --SUs/mhM/C8VTfn2w Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQRh246EGq/8RLhDjO14tDGHoIJi0gUCZt7hrQAKCRB4tDGHoIJi 0ucHAQCjkWwsUr+Tf13mvf/NIW8TxI0fFZYidIvfu2FZrQ6WAQEA74PlsEXjODkK cpamVx+2CMaasJI43MaDxnWfquAS/QU= =+ur3 -----END PGP SIGNATURE----- --SUs/mhM/C8VTfn2w--