From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH v7 2/3] KVM: x86: trace mmio begin and complete Date: Mon, 03 Sep 2012 14:07:30 +0300 Message-ID: <50448F72.80702@redhat.com> References: <1346061106-5364-1-git-send-email-haodong@linux.vnet.ibm.com> <1346061106-5364-3-git-send-email-haodong@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: acme@infradead.org, mtosatti@redhat.com, mingo@elte.hu, xiaoguangrong@linux.vnet.ibm.com, linux-kernel@vger.kernel.org, kvm@vger.kernel.org To: Dong Hao Return-path: In-Reply-To: <1346061106-5364-3-git-send-email-haodong@linux.vnet.ibm.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 08/27/2012 12:51 PM, Dong Hao wrote: > From: Xiao Guangrong > > 'perf kvm stat record/report' 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_io_done to trace the time when mmio/pio is > completed > Why is this so critical? If a lot of time is spent in in-kernel mmio, then 'perf top' will report it. Otherwise the time between kvm_exit and kvm_entry describes the time spent in the host. Not all of it is mmio handling, but it is quite close. -- error compiling committee.c: too many arguments to function