From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756141Ab2DXBEG (ORCPT ); Mon, 23 Apr 2012 21:04:06 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122]:11573 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756050Ab2DXBEC (ORCPT ); Mon, 23 Apr 2012 21:04:02 -0400 X-Authority-Analysis: v=2.0 cv=V/z/IJbi c=1 sm=0 a=ZycB6UtQUfgMyuk2+PxD7w==:17 a=XQbtiDEiEegA:10 a=unLN5eZtZcEA:10 a=5SG0PmZfjMsA:10 a=Q9fys5e9bTEA:10 a=BuleduMwnqcLhVulvM8A:9 a=elNPHhPqOPENFrO53C4A:7 a=PUjeQqilurYA:10 a=ZycB6UtQUfgMyuk2+PxD7w==:117 X-Cloudmark-Score: 0 X-Originating-IP: 74.67.80.29 Message-ID: <1335229437.28106.131.camel@gandalf.stny.rr.com> Subject: Re: [PATCH 05/16] sched: SCHED_DEADLINE policy implementation. From: Steven Rostedt To: Peter Zijlstra Cc: Tommaso Cucinotta , Juri Lelli , tglx@linutronix.de, mingo@redhat.com, cfriesen@nortel.com, oleg@redhat.com, fweisbec@gmail.com, darren@dvhart.com, johan.eker@ericsson.com, p.faure@akatech.ch, linux-kernel@vger.kernel.org, claudio@evidence.eu.com, michael@amarulasolutions.com, fchecconi@gmail.com, nicola.manica@disi.unitn.it, luca.abeni@unitn.it, dhaval.giani@gmail.com, hgu1972@gmail.com, paulmck@linux.vnet.ibm.com, raistlin@linux.it, insop.song@ericsson.com, liming.wang@windriver.com Date: Mon, 23 Apr 2012 21:03:57 -0400 In-Reply-To: <1335218328.28150.181.camel@twins> References: <1333696481-3433-1-git-send-email-juri.lelli@gmail.com> <1333696481-3433-6-git-send-email-juri.lelli@gmail.com> <1335182113.28150.132.camel@twins> <4F95CFBF.1050000@sssup.it> <1335218328.28150.181.camel@twins> Content-Type: text/plain; charset="ISO-8859-15" X-Mailer: Evolution 3.2.2-1 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2012-04-23 at 23:58 +0200, Peter Zijlstra wrote: > On Mon, 2012-04-23 at 22:55 +0100, Tommaso Cucinotta wrote: > > why not write this straight in asm, i.e., multiply 64*64 then divide by > > 64 keeping the intermediate result on 128 bits? > > If you know of a way to do this for all 30 odd architectures supported > by our beloved kernel, do let me know ;-) > > Yes I can do it for x86_64, but people tend to get mighty upset if you > break the compile for all other arches... Use the draconian method. Make SCHED_DEADLINE dependent on "ARCH_HAS_128_MULT" and any arch maintainer that wants SCHED_DEADLINE for their arch will be responsible for implementing it ;-) -- Steve