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[209.132.180.67]) by mx.google.com with ESMTP id s6-v6si1797354pgg.41.2018.08.17.03.36.25; Fri, 17 Aug 2018 03:36:40 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726950AbeHQNhm (ORCPT + 99 others); Fri, 17 Aug 2018 09:37:42 -0400 Received: from foss.arm.com ([217.140.101.70]:45804 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726608AbeHQNhl (ORCPT ); Fri, 17 Aug 2018 09:37:41 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 0D8C97A9; Fri, 17 Aug 2018 03:34:46 -0700 (PDT) Received: from queper01-lin (queper01-lin.emea.arm.com [10.4.13.27]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 3F2B43F5BD; Fri, 17 Aug 2018 03:34:43 -0700 (PDT) Date: Fri, 17 Aug 2018 11:34:38 +0100 From: Quentin Perret To: Patrick Bellasi Cc: Juri Lelli , linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, Ingo Molnar , Peter Zijlstra , Tejun Heo , "Rafael J . Wysocki" , Viresh Kumar , Vincent Guittot , Paul Turner , Dietmar Eggemann , Morten Rasmussen , Todd Kjos , Joel Fernandes , Steve Muckle , Suren Baghdasaryan Subject: Re: [PATCH v3 01/14] sched/core: uclamp: extend sched_setattr to support utilization clamping Message-ID: <20180817103406.gmve4clcxmhwlmtc@queper01-lin> References: <20180806163946.28380-1-patrick.bellasi@arm.com> <20180806163946.28380-2-patrick.bellasi@arm.com> <20180807123550.GA3062@localhost.localdomain> <20180809091427.4p2c4fbxocpkjaby@darkstar> <20180809095043.GC22465@localhost.localdomain> <20180809152313.lewfhufidhxb2qrk@darkstar> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180809152313.lewfhufidhxb2qrk@darkstar> User-Agent: NeoMutt/20171215 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Patrick, On Thursday 09 Aug 2018 at 16:23:13 (+0100), Patrick Bellasi wrote: > On 09-Aug 11:50, Juri Lelli wrote: > > On 09/08/18 10:14, Patrick Bellasi wrote: > > > On 07-Aug 14:35, Juri Lelli wrote: > > > > On 06/08/18 17:39, Patrick Bellasi wrote: > > [...] > > > > 1) make CAP_SYS_NICE protected the clamp groups, with an optional boot > > > time parameter to relax this check > > > > It seems to me that this might work well with that the intended usage of > > the interface that you depict above. SMS only (or any privileged user) > > will be in control of how groups are configured, so no problem for > > normal users. > > Yes, well... apart normal users still getting a -ENOSPC is they are > requesting one of the not pre-configured clamp values. Which is why > the following bits can be helpful. So IIUC, normal users would still be free of choosing their clamp values as long as they choose one in the list of pre-allocated ones ? Is that correct ? If yes, that would still let normal users make they tasks look bigger no ? They could just choose the clamp group with the highest min_clamp or something. Isn't this a problem too ? I mean, if that can be abused easily, I'm pretty sure people _will_ abuse it ... Or maybe I misunderstood something ? Thanks, Quentin