From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030284Ab2CMJ5l (ORCPT ); Tue, 13 Mar 2012 05:57:41 -0400 Received: from damascus.uab.es ([158.109.168.135]:62614 "EHLO damascus.uab.es" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965083Ab2CMJ5j (ORCPT ); Tue, 13 Mar 2012 05:57:39 -0400 Date: Tue, 13 Mar 2012 11:58:05 +0100 From: Davidlohr Bueso Subject: Re: [PATCH] KVM: VMX: add tracepoint for vpids In-reply-to: <4F5DD140.7040605@redhat.com> To: Avi Kivity Cc: Marcelo Tosatti , lkml , KVM Message-id: <1331636285.12394.4.camel@offworld> Organization: GNU MIME-version: 1.0 X-Mailer: Evolution 3.0.3-2 Content-type: text/plain; charset=UTF-8 Content-transfer-encoding: 7BIT X-Spam-Tests: ALL_TRUSTED=-1 X-imss-version: 2.054 X-imss-result: Passed X-imss-scanInfo: M:P L:N SM:0 X-imss-tmaseResult: TT:0 TS:0.0000 TC:00 TRN:0 TV:6.5.1024(18770.005) X-imss-scores: Clean:99.90000 C:2 M:3 S:5 R:5 X-imss-settings: Baseline:3 C:3 M:3 S:3 R:3 (0.5000 0.5000) References: <1331481472.17316.1.camel@offbook> <4F5DB245.9060205@redhat.com> <1331551781.1334.3.camel@offworld> <4F5DD140.7040605@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2012-03-12 at 12:34 +0200, Avi Kivity wrote: > On 03/12/2012 01:29 PM, Davidlohr Bueso wrote: > > On Mon, 2012-03-12 at 10:22 +0200, Avi Kivity wrote: > > > On 03/11/2012 05:57 PM, Davidlohr Bueso wrote: > > > > From: Davidlohr Bueso > > > > > > > > Add a new tracepoint for vpid allocation and freeing associated to all vCPUs. > > > > > > > > > > Why? > > > > > > > We have been using this tracepoint for some time now to help debug vpids > > and simulating tagged TLB behavior and performance. This gets to be non > > trivial when working with large amounts of guests and vCPUs. > > I don't follow. Can you give an example of when this tracepoint would > be useful? > For example when running lots of guests with many different hardware configurations (ept on/off, vpid on/off) I trace what vcpu has or doesn't have a corresponding vpid associated. Perhaps this is more useful for experimental things than actual KVM development.