From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755090Ab2IFIFv (ORCPT ); Thu, 6 Sep 2012 04:05:51 -0400 Received: from mx1.redhat.com ([209.132.183.28]:22560 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752054Ab2IFIFo (ORCPT ); Thu, 6 Sep 2012 04:05:44 -0400 Message-ID: <50485954.50204@redhat.com> Date: Thu, 06 Sep 2012 11:05:40 +0300 From: Avi Kivity User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:14.0) Gecko/20120717 Thunderbird/14.0 MIME-Version: 1.0 To: dave@gnu.org CC: Marcelo Tosatti , KVM , lkml Subject: Re: [PATCH] KVM: VMX: invalidate vpid for invlpg instruction References: <1346429448.2823.1.camel@offbook> <20120831173707.GA3895@amt.cnet> <1346628440.3170.3.camel@offbook> <50447442.2050307@redhat.com> <1346882061.6304.17.camel@offbook> In-Reply-To: <1346882061.6304.17.camel@offbook> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/06/2012 12:54 AM, Davidlohr Bueso wrote: > On Mon, 2012-09-03 at 12:11 +0300, Avi Kivity wrote: >> On 09/03/2012 02:27 AM, Davidlohr Bueso wrote: >> > On Fri, 2012-08-31 at 14:37 -0300, Marcelo Tosatti wrote: >> >> On Fri, Aug 31, 2012 at 06:10:48PM +0200, Davidlohr Bueso wrote: >> >> > For processors that support VPIDs we should invalidate the page table entry >> >> > specified by the lineal address. For this purpose add support for individual >> >> > address invalidations. >> >> >> >> Not necessary - a single context invalidation is performed through >> >> KVM_REQ_TLB_FLUSH. >> > >> > Since vpid_sync_context() supports both single and all-context vpid >> > invalidations, wouldn't it make sense to also add individual address >> > ones as well, supporting further granularity? >> >> It might. Do you have benchmarks supporting this? >> > > I ran two benchmarks: Java Dacapo[1] Sunflow (renders a set of images > using ray tracing) and a vanilla 3.2 kernel build (with 1 job and -j8). > > The host configuration is an Intel i7-2635QM (4 cores + HT) with 4Gb RAM > running Linus's latest and only running standard system daemons. For KVM > I disabled EPT. That's not very interesting. In all real machines, if you have VPID you also have EPT. Intel are unlikely to produce a processor without EPT. > The guest configuration is a 64bit 4 core 4Gb RAM, running Linux 3.2 > (debian) and only running the benchmark. > > All results represent the mean of 5 runs, with time(1). The results are impressive, but lack real-world relevance. Individual-address invalidation isn't very useful with EPT, since we let the guest issue INVLPG itself and otherwise don't bother with guest page tables. Individual-address INVEPT would probably be more useful, but there is no such instruction variant. -- error compiling committee.c: too many arguments to function