From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rik van Riel Subject: Re: [RFC PATCH 2/3] sched: add yield_to function Date: Sat, 04 Dec 2010 08:02:31 -0500 Message-ID: <4CFA3BE7.4050905@redhat.com> References: <20101202144129.4357fe00@annuminas.surriel.com> <20101202144423.3ad1908d@annuminas.surriel.com> <1291382619.32004.2124.camel@laptop> <20101203133056.GF27994@linux.vnet.ibm.com> <1291385010.32004.2165.camel@laptop> <20101203140607.GA9800@linux.vnet.ibm.com> <20101203141037.GE16411@linux.vnet.ibm.com> <1291411391.2032.4.camel@laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: vatsa@linux.vnet.ibm.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Avi Kiviti , Ingo Molnar , Anthony Liguori To: Peter Zijlstra Return-path: Received: from mx1.redhat.com ([209.132.183.28]:32692 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753070Ab0LDNDE (ORCPT ); Sat, 4 Dec 2010 08:03:04 -0500 In-Reply-To: <1291411391.2032.4.camel@laptop> Sender: kvm-owner@vger.kernel.org List-ID: On 12/03/2010 04:23 PM, Peter Zijlstra wrote: > On Fri, 2010-12-03 at 19:40 +0530, Srivatsa Vaddagiri wrote: >> On Fri, Dec 03, 2010 at 07:36:07PM +0530, Srivatsa Vaddagiri wrote: >>> On Fri, Dec 03, 2010 at 03:03:30PM +0100, Peter Zijlstra wrote: >>>> No, because they do receive service (they spend some time spinning >>>> before being interrupted), so the respective vruntimes will increase, at >>>> some point they'll pass B0 and it'll get scheduled. >>> >>> Is that sufficient to ensure that B0 receives its fair share (1/3 cpu in this >>> case)? >> >> Hmm perhaps yes, althought at cost of tons of context switches, which would be >> nice to minimize on? > > Don't care, as long as the guys calling yield_to() pay for that time its > their problem. Also, the context switches are cheaper than spinning entire time slices on spinlocks we're not going to get (because the VCPU holding the lock is not running). -- All rights reversed