From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751621AbaLQMtM (ORCPT ); Wed, 17 Dec 2014 07:49:12 -0500 Received: from service87.mimecast.com ([91.220.42.44]:52114 "EHLO service87.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751118AbaLQMtL convert rfc822-to-8bit (ORCPT ); Wed, 17 Dec 2014 07:49:11 -0500 Message-ID: <54917BCC.9070001@arm.com> Date: Wed, 17 Dec 2014 12:49:16 +0000 From: Juri Lelli User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 MIME-Version: 1.0 To: Luca Abeni , Peter Zijlstra CC: Ingo Molnar , Juri Lelli , Dario Faggioli , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH 0/2] SCHED_DEADLINE fixes References: <1418813432-20797-1-git-send-email-luca.abeni@unitn.it> In-Reply-To: <1418813432-20797-1-git-send-email-luca.abeni@unitn.it> X-OriginalArrivalTime: 17 Dec 2014 12:49:07.0590 (UTC) FILETIME=[D8A2AA60:01D019F7] X-MC-Unique: 114121712490814901 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Luca, On 17/12/14 10:50, Luca Abeni wrote: > Hi all, > > I noticed some discrepancies between the schedule produced > by SCHED_DEADLINE and the expectations from real-time > scheduling theory. After some investigations, it turned out > that such discrepancies are due to two bugs in deadline.c, > which are particularly visible when using global scheduling > on multiple CPUs (see the two patches for more details). > > I think the first bug (fixed in patch 0001) is particularly > critical, because it causes a violation of the SCHED_DEADLINE > guarantee (if the total load is smaller than the number of > CPUs, there is an upper bound for the response times. This is > a well known property for global EDF, but is not respected by > SCHED_DEADLINE - see patch 0001 for more details). > The second patch is IMHO also important, but less critical. > I already reviewed and tested them. They looks ok and are important fixes. ACK for both. :) Thanks a lot! - Juri > Luca Abeni (2): > Fix migration of SCHED_DEADLINE tasks > Avoid double-accounting in case of missed deadlines > > kernel/sched/deadline.c | 25 ++++--------------------- > 1 file changed, 4 insertions(+), 21 deletions(-) >