From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 445313BA246; Tue, 1 Sep 2026 12:21:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788265319; cv=none; b=fvaZMihllGD2ZdZzFlbaHyDgm8HiHCu8J1ew4sFgdPDZx4hxasdWAHtZCucAHSRWGnbwC7jZVoJViGqTT509hDXAtYd+sGJ88Jy8jOWgkUtUWQXNdsOfNlXcNo70NIE/BiWOqj7KaWCo3yuwRT1eHSVho3zpeQttUQhAqBOI6Pw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788265319; c=relaxed/simple; bh=GTAV1btrciy8QWORbwi47W3ulx/1ZieXdXfDbZrZxsk=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=IInOFpHSLHpHcpifuEGX0j0lFArLgf9ePbsb3jfGWCnGo3xqVYTAj/OW79gQnXjpVjjA3RFeQjtn0uEVnkLuH+69GVeJwk42+xf7YXO3LKqxdehYDp/ELGJAaJRAV1UJQE/kqoAgRk+MO1Gy5Pu2f6B3EvghTNvlxaqkThRdDsA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=fTQWBEmy; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="fTQWBEmy" Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id D8F351756; Tue, 1 Sep 2026 05:21:51 -0700 (PDT) Received: from [192.168.178.6] (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 68BBE3F85F; Tue, 1 Sep 2026 05:21:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1788265315; bh=GTAV1btrciy8QWORbwi47W3ulx/1ZieXdXfDbZrZxsk=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=fTQWBEmyPuLjDIFIOCsXXBnQ6v5dqPWKi5VUWTFfbkkypETbpDop7Xbd0kaRH7EON /M7epJ8PP7scyLzzpTqJSvL6JOuikn59kEtFuQqudt4R8rEQinSRDadvhPXOKsqu6F 9/2xo6l5xY0mb4wZQFr8kq6RHiln9PGVi2UeGvJs= Message-ID: <3368b089-32ce-4521-ab19-e37c9f029b8b@arm.com> Date: Tue, 1 Sep 2026 14:21:40 +0200 Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v11 05/12] sched/core: Try to use a preferred CPU in is_cpu_allowed To: Vincent Guittot , Yury Norov Cc: Shrikanth Hegde , linux-kernel@vger.kernel.org, mingo@kernel.org, peterz@infradead.org, juri.lelli@redhat.com, yury.norov@gmail.com, kprateek.nayak@amd.com, iii@linux.ibm.com, corbet@lwn.net, meted@linux.ibm.com, tglx@kernel.org, gregkh@linuxfoundation.org, pbonzini@redhat.com, seanjc@google.com, vschneid@redhat.com, huschle@linux.ibm.com, rostedt@goodmis.org, maddy@linux.ibm.com, srikar@linux.ibm.com, hdanton@sina.com, chleroy@kernel.org, vineeth@bitbyteword.org, frederic@kernel.org, arighi@nvidia.com, pauld@redhat.com, christian.loehle@arm.com, tj@kernel.org, tommaso.cucinotta@gmail.com, maz@kernel.org, rafael@kernel.org, rdunlap@infradead.org, kernellwp@gmail.com, linux-doc@vger.kernel.org, jgross@suse.com, virtualization@lists.linux.dev, sunlightlinux@gmail.com References: <20260825103855.721013-1-sshegde@linux.ibm.com> <20260825103855.721013-6-sshegde@linux.ibm.com> <8262d2f9-9f2f-4821-8497-991d7c8448a3@arm.com> <53035ba4-53ec-4907-93b8-c8b957d1fa61@linux.ibm.com> Content-Language: en-GB From: Dietmar Eggemann In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 01.09.26 08:21, Vincent Guittot wrote: > On Mon, 31 Aug 2026 at 18:54, Yury Norov wrote: >> >> On Mon, Aug 31, 2026 at 05:09:41PM +0200, Vincent Guittot wrote: >> >>>> Dietmar/Vincent, >>>> Do you think it makes sense to enable the driver on ARM64 now? >>>> Or you think it is better to delay it and once the feature is stable >>>> ARM ecosystem can enable it? >>> >>> It's always better to support all arch by default, unless something is >>> missing which is not the case here. >> >> ARM64 testing is obviously missed. > > But the cpumask is already available not like if you need to create a new one IMHO, when testing the steal_governor on arm64 w/o `allow_mismatched_32bit_el0`, I wouldn't expect much difference in this respect compared to the architectures already tested. Also, AFAIK, `allow_mismatched_32bit_el0` was mainly relevant for Android devices up to Android 13 that supported 32-bit userspace, so I wouldn't expect it to be commonly enabled on recent devices. As Vincent pointed out, `task_cpu_possible_mask(p)` (which defaults to `cpu_possible_mask`) is already used in `kernel/sched/core.c` and `kernel/cgroup/cpuset.c` to support `allow_mismatched_32bit_el0`.