Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753410Ab2BTLxl (ORCPT ); Mon, 20 Feb 2012 06:53:41 -0500 Received: from e23smtp08.au.ibm.com ([202.81.31.141]:42393 "EHLO e23smtp08.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750951Ab2BTLxk (ORCPT ); Mon, 20 Feb 2012 06:53:40 -0500 From: Nikunj A Dadhania To: Peter Zijlstra , Avi Kivity Cc: Ingo Molnar , Rik van Riel , linux-kernel@vger.kernel.org, vatsa@linux.vnet.ibm.com, bharata@linux.vnet.ibm.com Subject: Re: [RFC PATCH 0/4] Gang scheduling in CFS In-Reply-To: <1329735073.2293.305.camel@twins> References: <20111230095147.GA10543@elte.hu> <878vlu4bgh.fsf@linux.vnet.ibm.com> <87pqf5mqg4.fsf@abhimanyu.in.ibm.com> <4F017AD2.3090504@redhat.com> <87mxa3zqm1.fsf@abhimanyu.in.ibm.com> <4F046536.5080207@redhat.com> <4F048295.1050907@redhat.com> <4F04898B.1080600@redhat.com> <1325712710.3084.10.camel@laptop> <4F04C789.40209@redhat.com> <20120105091059.GA3249@elte.hu> <87fwe6ork3.fsf@abhimanyu.in.ibm.com> <1329735073.2293.305.camel@twins> User-Agent: Notmuch/0.10.2+70~gf0e0053 (http://notmuchmail.org) Emacs/23.3.1 (x86_64-redhat-linux-gnu) Date: Mon, 20 Feb 2012 17:23:16 +0530 Message-ID: <877gzhpvpv.fsf@abhimanyu.in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii x-cbid: 12022001-5140-0000-0000-000000C597E8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1083 Lines: 26 On Mon, 20 Feb 2012 11:51:13 +0100, Peter Zijlstra wrote: > On Mon, 2012-02-20 at 13:38 +0530, Nikunj A Dadhania wrote: > > +#ifdef CONFIG_PARAVIRT_FLUSH_TLB > > + while (!cpumask_empty(to_cpumask(f->flush_cpumask)) && --loop) > > + cpu_relax(); > > + if (!loop && !cpumask_empty(to_cpumask(f->flush_cpumask))) > > + halt(); > > > That's just vile, you don't need to wait for it, all you need to make > sure is that when that vcpu wakes up it does the flush. > Yes, but we are not sure the vcpu will be sleeping or running. In the case where vcpus are running, it might be beneficial to wait a while. For example: If its a remote flush to only one of the vcpu and its already running, is it worthed to halt and come back? Regards, Nikunj -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/