From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: KVM performance vs. Xen Date: Thu, 30 Apr 2009 10:08:50 -0500 Message-ID: <49F9BF02.7090707@codemonkey.ws> References: <49F8672E.5080507@linux.vnet.ibm.com> <49F967AE.4040905@redhat.com> <49F9AB64.20506@codemonkey.ws> <49F9AD6B.3050300@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Andrew Theurer , kvm-devel To: Avi Kivity Return-path: Received: from mail-qy0-f196.google.com ([209.85.221.196]:53098 "EHLO mail-qy0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756300AbZD3PIx (ORCPT ); Thu, 30 Apr 2009 11:08:53 -0400 Received: by qyk34 with SMTP id 34so2417163qyk.33 for ; Thu, 30 Apr 2009 08:08:53 -0700 (PDT) In-Reply-To: <49F9AD6B.3050300@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: Avi Kivity wrote: > Anthony Liguori wrote: >> >>>> 2) cpu_physical_memory_rw due to not using preadv/pwritev? >>> >>> I think both virtio-net and virtio-blk use memcpy(). >> >> With latest linux-2.6, and a development snapshot of glibc, >> virtio-blk will not use memcpy() anymore but virtio-net still does on >> the receive path (but not transmit). > > There's still the kernel/user copy, so we have two copies on rx, one > on tx. That won't show up as cpu_physical_memory_rw. stl_phys/ldl_phys are suspect though as they degrade to cpu_physical_memory_rw. Regards, Anthony Liguori