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=-5.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 BCDF1C433ED for ; Thu, 20 May 2021 15:08:22 +0000 (UTC) Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (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 87F08611ED for ; Thu, 20 May 2021 15:08:22 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 87F08611ED 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=desiato.20200630; h=Sender:Content-Transfer-Encoding :Content-Type:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:Cc:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=W23/b7E0j7FOykg/hYw0VYg1Xqrq6V+xM7E4tGfUEqw=; b=gDf8J4t1PXlwCY3RWDumqe3BwJ KqNvlKiZnvdNkbQDzOJFQH6TNK/cEnLvB0DHSjChE4IFxgOBhPG7ggYIJ2cYyiaiyBsToUFKKqjwI rOXMApiv2RU2QBoKg8xKLLyp+ycLGv2ZGir/LKGoqrHbotXfionJoIKlasDoUbFN/4QzaCIBsVsKq 0EA6zeGb0cZ0HnWKLbVFBEiikqCAGXNSXdh/QuWFp26sClkI+1Z2ZWApnlyRyA/WcfD7ec3CoQp/T cPSe9UfuvGPODMYRmqlSU/EJHV+lXubzozqYsB66jHU8xrMQKP+bHv8yNKYXLaX2SfOyuhilmw8q8 jGu4Zwgg==; Received: from localhost ([::1] helo=desiato.infradead.org) by desiato.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1ljkGM-001bI6-Uv; Thu, 20 May 2021 15:07:04 +0000 Received: from bombadil.infradead.org ([2607:7c80:54:e::133]) by desiato.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1ljkGI-001bFO-LA for linux-arm-kernel@desiato.infradead.org; Thu, 20 May 2021 15:06:58 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=Content-Transfer-Encoding: Content-Type:In-Reply-To:MIME-Version:Date:Message-ID:From:References:Cc:To: Subject:Sender:Reply-To:Content-ID:Content-Description; bh=SviB3QizcBXT6g9KSQCEykm/xsseOYusSC/YUp1bIiY=; b=A/tK1wrhjmUnrTXeGx11SpO2J+ JsQKOGqiQlnOIY6cs7sGb8xWiV29prBFM+TgBkgzaEjpjTTd6FOaiJHmAgnh/kCErueuK+ZACxH30 Pj/qkf57TsLhcSbEB43KQQ1zLrhi07sPdIMn1IO/u52FRUdP8LSCwOdOKAVNKqYHck8E7JORemFah u8QVm5sZ325wRfFFKoHJDcRaKMWN2cmFBbAozmi7akqJV2FuitMWGHvv8AmwlPM8MRrL6/69YhlB3 RhnG2Z2X7JsJwgMyS8OJKHTesEJKVTJCJUEX4ldelvCppoeLQ2CIXa/g74t9MkEsG8gijkOtuXGu6 +r/EFKNg==; Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1ljkGF-00GRs6-Uo for linux-arm-kernel@lists.infradead.org; Thu, 20 May 2021 15:06:57 +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 CC3FD101E; Thu, 20 May 2021 08:06:51 -0700 (PDT) Received: from [192.168.1.16] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 5D5E53F73B; Thu, 20 May 2021 08:06:48 -0700 (PDT) Subject: Re: [PATCH v6 13/21] sched: Admit forcefully-affined tasks into SCHED_DEADLINE To: Daniel Bristot de Oliveira , Quentin Perret , Will Deacon Cc: Juri Lelli , linux-arm-kernel@lists.infradead.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, Catalin Marinas , Marc Zyngier , Greg Kroah-Hartman , Peter Zijlstra , Morten Rasmussen , Qais Yousef , Suren Baghdasaryan , Tejun Heo , Johannes Weiner , Ingo Molnar , Vincent Guittot , "Rafael J. Wysocki" , kernel-team@android.com References: <20210518094725.7701-1-will@kernel.org> <20210518094725.7701-14-will@kernel.org> <20210518102833.GA7770@willie-the-truck> <20210518105951.GC7770@willie-the-truck> <20210520101640.GA10065@willie-the-truck> From: Dietmar Eggemann Message-ID: <0dbdfe1e-dede-d33d-ca89-768a1fa3c907@arm.com> Date: Thu, 20 May 2021 17:06:42 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210520_080656_073847_D2BB4501 X-CRM114-Status: GOOD ( 20.45 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 20/05/2021 14:38, Daniel Bristot de Oliveira wrote: > On 5/20/21 12:33 PM, Quentin Perret wrote: >> On Thursday 20 May 2021 at 11:16:41 (+0100), Will Deacon wrote: >>> Ok, thanks for the insight. In which case, I'll go with what we discussed: >>> require admission control to be disabled for sched_setattr() but allow >>> execve() to a 32-bit task from a 64-bit deadline task with a warning (this >>> is probably similar to CPU hotplug?). >> >> Still not sure that we can let execve go through ... It will break AC >> all the same, so it should probably fail as well if AC is on IMO >> > > If the cpumask of the 32-bit task is != of the 64-bit task that is executing it, > the admission control needs to be re-executed, and it could fail. So I see this > operation equivalent to sched_setaffinity(). This will likely be true for future > schedulers that will allow arbitrary affinities (AC should run on affinity > change, and could fail). > > I would vote with Juri: "I'd go with fail hard if AC is on, let it > pass if AC is off (supposedly the user knows what to do)," (also hope nobody > complains until we add better support for affinity, and use this as a motivation > to get back on this front). > > -- Daniel (1) # chrt -d -T 5000000 -P 16666666 0 ./32bit_app (2) # ./32bit_app & # chrt -d -T 5000000 -P 16666666 -p 0 pid_of(32bit_app) Wouldn't the behaviour of (1) and (2) be different w/o this patch? In (1) __sched_setscheduler() happens before execve so it operates on p->cpus_ptr equal span. In (2) span != p->cpus_ptr so DL AC will fail. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel