From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CF4A1C55178 for ; Wed, 21 Oct 2020 14:33:30 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 4ABBE22249 for ; Wed, 21 Oct 2020 14:33:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="Lq5Bu2hi" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4ABBE22249 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=hVzBYWLsUoyZ0+g0dweGmTUIa4JEMKqQ5mgwTj/7ECk=; b=Lq5Bu2hiRm2ZYxcEOH3L+/Z4a 5/uCXxlt513GgcF70BKTBoG+S5vQ+2tQn2zIeKhMeYmGPMKAR1s6xY6Kb22D+9MJW7K28Tm3xA0nF ew9maaCacqOo2c8a2LJju/AD9sRbUqdpx3NJNyU3M1PNDV0w30KwCBxR3pf/gPCJU3QMqOXGdPoTW 6AgRPREyboLnvkYiBYWCHDbJmim4ktt1iDBoL7hdBbPFBmxuIxWVkJi7DRvvcRSF9cot2zbj8Hma5 HI5BFKd/cR3T6j9KmDdhYEsrTSDSx0YmOAKRH6uUxKa1qQCx+5m/RUNkAuvWFwZWgGEg4GBEtt3SQ hdjd1movg==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kVF9m-0004zQ-6X; Wed, 21 Oct 2020 14:32:03 +0000 Received: from foss.arm.com ([217.140.110.172]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kVF9j-0004ya-Ep for linux-arm-kernel@lists.infradead.org; Wed, 21 Oct 2020 14:32:00 +0000 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 AF398D6E; Wed, 21 Oct 2020 07:31:57 -0700 (PDT) Received: from e107158-lin (e107158-lin.cambridge.arm.com [10.1.194.78]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 5E3783F66B; Wed, 21 Oct 2020 07:31:56 -0700 (PDT) Date: Wed, 21 Oct 2020 15:31:53 +0100 From: Qais Yousef To: Morten Rasmussen Subject: Re: [RFC PATCH v2 4/4] arm64: Export id_aar64fpr0 via sysfs Message-ID: <20201021143153.7ef7n7gdd42l4rbc@e107158-lin> References: <20201021104611.2744565-1-qais.yousef@arm.com> <20201021104611.2744565-5-qais.yousef@arm.com> <63fead90e91e08a1b173792b06995765@kernel.org> <20201021121559.GB3976@gaia> <20201021133316.GF8004@e123083-lin> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20201021133316.GF8004@e123083-lin> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201021_103159_591487_A487C278 X-CRM114-Status: GOOD ( 15.94 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arch@vger.kernel.org, Marc Zyngier , "Peter Zijlstra \(Intel\)" , Catalin Marinas , Linus Torvalds , James Morse , Greg Kroah-Hartman , Will Deacon , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 10/21/20 15:33, Morten Rasmussen wrote: > On Wed, Oct 21, 2020 at 01:15:59PM +0100, Catalin Marinas wrote: > > one, though not as easy as automatic task placement by the scheduler (my > > first preference, followed by the id_* regs and the aarch32 mask, though > > not a strong preference for any). > > Automatic task placement by the scheduler would mean giving up the > requirement that the user-space affinity mask must always be honoured. > Is that on the table? > > Killing aarch32 tasks with an empty intersection between the user-space > mask and aarch32_mask is not really "automatic" and would require the > aarch32 capability to be exposed anyway. I just noticed this nasty corner case too. Documentation/admin-guide/cgroup-v1/cpusets.rst: Section 1.9 "If such a task had been bound to some subset of its cpuset using the sched_setaffinity() call, the task will be allowed to run on any CPU allowed in its new cpuset, negating the effect of the prior sched_setaffinity() call." So user space must put the tasks into a valid cpuset to fix the problem. Or make the scheduler behave like the affinity is associated with a cpuset. Can user space put the task into the correct cpuset without a race? Clone3 syscall learnt to specify a cgroup to attach to when forking. Should we do the same for execve()? Thanks -- Qais Yousef _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel