From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH v2 2/3] KVM: x86: add tracepoints to trace mmio begin and complete Date: Thu, 02 Feb 2012 19:56:22 +0200 Message-ID: <4F2ACE46.4000307@redhat.com> References: <4F2AC707.7020801@gmail.com> <4F2AC790.1090805@gmail.com> <4F2AC9A0.7090904@redhat.com> <4F2ACE04.9040602@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: Marcelo Tosatti , Ingo Molnar , Arnaldo Carvalho de Melo , Stefan Hajnoczi , LKML , KVM To: Xiao Guangrong Return-path: In-Reply-To: <4F2ACE04.9040602@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 02/02/2012 07:55 PM, Xiao Guangrong wrote: > On 02/03/2012 01:36 AM, Avi Kivity wrote: > > > On 02/02/2012 07:27 PM, Xiao Guangrong wrote: > >> From: Xiao Guangrong > >> > >> 'perf kvm-events' will use kvm_exit and kvm_mmio(read...) to calculate > >> mmio read emulated time for the old kernel, in order to trace mmio read > >> event more exactly, we add kvm_mmio_begin to trace the time when mmio read > >> begins > >> > >> Also, add kvm_mmio_done to trace the time when mmio/pio is completed > > > > Previously, we discussed using the kvm_entry to do this. This reduces > > the number of tracepoints, and is backwards compatible. What was the > > conclusion? > > > > > Since using kvm_entry can cause lots of unnecessary calculated, these new two > tracepoints can let the result be exacter. Do you have numbers on the ratio between kvm_entry traces and kvm_mmio_begin/end traces? > And, they are only used in new kernel, we will fall back to using kvm_entry if > they are not existing, that means it does not break backwards compatible. Ah ok. -- error compiling committee.c: too many arguments to function