From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933166AbXCNUXq (ORCPT ); Wed, 14 Mar 2007 16:23:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933226AbXCNUXq (ORCPT ); Wed, 14 Mar 2007 16:23:46 -0400 Received: from smtp-outbound-1.vmware.com ([65.113.40.141]:44522 "EHLO smtp-outbound-1.vmware.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933166AbXCNUXp (ORCPT ); Wed, 14 Mar 2007 16:23:45 -0400 Message-ID: <45F859CF.8040100@vmware.com> Date: Wed, 14 Mar 2007 12:23:43 -0800 From: Zachary Amsden User-Agent: Thunderbird 1.5.0.10 (X11/20070221) MIME-Version: 1.0 To: Benjamin LaHaise CC: Jeremy Fitzhardinge , Andi Kleen , Andrew Morton , linux-kernel@vger.kernel.org, virtualization@lists.osdl.org, xen-devel@lists.xensource.com, Chris Wright , Rusty Russell , Ingo Molnar , Andi Kleen Subject: Re: [patch 28/34] Xen-pv_ops: Xen SMP guest support References: <20070313233017.933601256@goop.org> <20070313233034.586018620@goop.org> <20070314132820.GL6209@kvack.org> In-Reply-To: <20070314132820.GL6209@kvack.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Benjamin LaHaise wrote: > >> +/* >> + * We aggressively remove defunct pgd from cr3. We execute unmap_vmas() >> + * *much* faster this way. >> + */ >> > > Are you switching mms in order to avoid all of the overhead associated with > flushing an active mm during task exit? If so, it makes much more sense to > do this in the generic helper, as it should be a win on x86 and x86-64 > where switching to init_mm is relatively low cost given the support for > global pages. I'll run some tests on a couple of systems this evening and > post the results. > I tried this experiment on both x86 and x86-64 and I recall not seeing any effect. The mmu_gather optimization does most of this already. Zach