From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752990AbbKPJDr (ORCPT ); Mon, 16 Nov 2015 04:03:47 -0500 Received: from bombadil.infradead.org ([198.137.202.9]:42035 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752376AbbKPJDj (ORCPT ); Mon, 16 Nov 2015 04:03:39 -0500 Date: Mon, 16 Nov 2015 10:03:33 +0100 From: Peter Zijlstra To: Luiz Capitulino Cc: Marcelo Tosatti , Thomas Gleixner , Vikas Shivappa , Tejun Heo , Yu Fenghua , linux-kernel@vger.kernel.org Subject: Re: [PATCH RFC] ioctl based CAT interface Message-ID: <20151116090333.GL17308@twins.programming.kicks-ass.net> References: <20151113163933.GA10222@amt.cnet> <20151113165100.GI17308@twins.programming.kicks-ass.net> <20151113172740.GA13490@amt.cnet> <20151113140438.3d8e2e11@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20151113140438.3d8e2e11@redhat.com> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 13, 2015 at 02:04:38PM -0500, Luiz Capitulino wrote: > I guess that what Peter is saying is that we don't want tasks > attached to a reservation landing on a CPU where the reservation > might be different or not existent at all. Correct. > This way, the ATTACH_RESERVATION command would fail if any > of the CPUs in the cpumask are not part of the reservation. > And then our code would have to be notified any time the process' > affinity mask is changed (we either fail the affinity change > or detach the process automatically from the reservation). Does > this sound like a good solution? No. We're not going to have random drivers muck about with affinity masks, and most certainly not some manky ioctl.