From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752793Ab0CPWan (ORCPT ); Tue, 16 Mar 2010 18:30:43 -0400 Received: from 8bytes.org ([88.198.83.132]:40202 "EHLO 8bytes.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751104Ab0CPWam (ORCPT ); Tue, 16 Mar 2010 18:30:42 -0400 Date: Tue, 16 Mar 2010 23:30:40 +0100 From: oerg Roedel To: Ingo Molnar Cc: Avi Kivity , "Zhang, Yanmin" , Peter Zijlstra , Sheng Yang , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Marcelo Tosatti , Jes Sorensen , Gleb Natapov , Zachary Amsden , ziteng.huang@intel.com Subject: Re: [PATCH] Enhance perf to collect KVM guest os statistics from host side Message-ID: <20100316223040.GH13108@8bytes.org> References: <4B9F19F7.6000309@redhat.com> <20100316072449.GB11881@elte.hu> <4B9F4D74.4090403@redhat.com> <20100316095336.GI7961@elte.hu> <4B9F59DE.1060008@redhat.com> <20100316102052.GC10069@elte.hu> <4B9F603B.4080004@redhat.com> <20100316105021.GA14344@elte.hu> <4B9F671D.5060001@redhat.com> <20100316112500.GA5337@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100316112500.GA5337@elte.hu> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 16, 2010 at 12:25:00PM +0100, Ingo Molnar wrote: > Hm, that sounds rather messy if we want to use it to basically expose kernel > functionality in a guest/host unified way. Is the qemu process discoverable in > some secure way? Can we trust it? Is there some proper tooling available to do > it, or do we have to push it through 2-3 packages to get such a useful feature > done? Since we want to implement a pmu usable for the guest anyway why we don't just use a guests perf to get all information we want? If we get a pmu-nmi from the guest we just re-inject it to the guest and perf in the guest gives us all information we wand including kernel and userspace symbols, stack traces, and so on. In the previous thread we discussed about a direct trace channel between guest and host kernel (which can be used for ftrace events for example). This channel could be used to transport this information to the host kernel. The only additional feature needed is a way for the host to start a perf instance in the guest. Opinions? Joerg