From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 01F10332628; Fri, 27 Feb 2026 20:14:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772223267; cv=none; b=ru2beMHm2Mj74WdxE3Eyajpstr/JzCYjZJOg0kJAvRUlV6IYvXrtDgwyTY2JruCisnBGJuXfKh/B4b9mAF9Gw1wUNtORiOEgc17+JtZfNYyMT7l/Cag64IOfmofRO/PbBnPlJLSZn/5Y/RRqujm0z83wEFLfaM/tha87XP+SNFk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772223267; c=relaxed/simple; bh=+KOSKxsoGYY/7fsMQ88t/V8gy5v0QwKSCr+e29jLYas=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=hals38iG+CdIcBRDxDMj5WGIJRwXua5+bfH6UMTgkbmEj2+V7Oo0BVd6sevFwnIediHpsAdSqoHZK1KJ3dl+gQY8a1nsJju71UdXyxp9QN7BnFsIM/TqATR3u5KUhkqtHYWqdFeQSzBtKFZYb478IjQF2OPoh4U7wMPOa0bj5us= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=uTAk1+ab; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="uTAk1+ab" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BAC27C116C6; Fri, 27 Feb 2026 20:14:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772223266; bh=+KOSKxsoGYY/7fsMQ88t/V8gy5v0QwKSCr+e29jLYas=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=uTAk1+abXF7bulJl0Gq9qUj3wxpGCKecjwd4JWztwPUccptJKU++M4vQGoOzkyeCG 34FAs6yFS54QKh/J3H9JBK9iX144MGBGKqDUcqJyvKAqWEMD4WZZMrfib0kaFGkMkg Bt+/XTb6+bTwoeWV15wXCQJciBR74MyYanQq7Py6O8gWuU+3hBcXvJtuyhs6PVyjtT 3xmlGfhGAHfdXfo9nSkShvwNjxU2m/eZM5rfzvCEZwiVC3yWT09mWF5lAaIVBQXxdU Cm+n8wQ6dtJa8NpHxcdfsyrf7Evn09hj1pVMdMlkpeJHifPmxutjo3ZxeChmJmwNIK ZUy0wm7IVoC+Q== Date: Fri, 27 Feb 2026 10:14:25 -1000 From: Tejun Heo To: Andrea Righi Cc: linux-kernel@vger.kernel.org, sched-ext@lists.linux.dev, void@manifault.com, changwoo@igalia.com, emil@etsalapatis.com, hannes@cmpxchg.org, mkoutny@suse.com, cgroups@vger.kernel.org Subject: Re: [PATCH 07/34] sched_ext: Introduce cgroup sub-sched support Message-ID: References: <20260225050109.1070059-1-tj@kernel.org> <20260225050109.1070059-8-tj@kernel.org> Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Hello, On Thu, Feb 26, 2026 at 04:37:55PM +0100, Andrea Righi wrote: > On Tue, Feb 24, 2026 at 07:00:42PM -1000, Tejun Heo wrote: > ... > > diff --git a/init/Kconfig b/init/Kconfig > > index c25869cf59c1..96ba2fa08883 100644 > > --- a/init/Kconfig > > +++ b/init/Kconfig > > @@ -1176,6 +1176,10 @@ config EXT_GROUP_SCHED > > > > endif #CGROUP_SCHED > > > > +config EXT_SUB_SCHED > > + def_bool y > > + depends on SCHED_CLASS_EXT > > + > > It would be nice if we could opt to not build this. Also, if I disable > CONFIG_CGROUP: > > kernel/sched/ext.c: In function ‘scx_dispatch_sched’: > kernel/sched/ext.c:2454:52: error: ‘struct sched_ext_entity’ has no member named ‘sched’ > 2454 | sch == rcu_access_pointer(prev->scx.sched); > | ^ Build bug is fixed. We can make CONFIG_EXT_SUB_SCHED a selectable config option, but I'm not sure what that buys us. In terms of kernel image overhead, it's not going to be anything substantial and it shouldn't add noticeable hot path overhead either. In general, I'm not a big fan of introducing selectable config options unless there are justifiable benefits. Thanks. -- tejun