From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Marchand Subject: Re: [Qemu-devel] Why I advise against using ivshmem Date: Wed, 18 Jun 2014 16:58:25 +0200 Message-ID: <53A1A911.9040407@6wind.com> References: <20140612094413.15e56938@nbschild1> <87vbs6qjhj.fsf_-_@blackfin.pond.sub.org> <5399CF09.8030803@6wind.com> <87ppidnqmy.fsf@blackfin.pond.sub.org> <539AC3E0.9090404@6wind.com> <539ACDE6.7020709@redhat.com> <539AFF7C.7090702@6wind.com> <539B064D.2050501@redhat.com> <53A00464.8090609@6wind.com> <20140618105120.GI14030@stefanha-thinkpad.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Paolo Bonzini , Vincent JARDIN , Henning Schild , Olivier MATZ , kvm , qemu-devel , Linux Virtualization , "thomas.monjalon@6wind.com" To: Stefan Hajnoczi Return-path: Received: from mail-we0-f172.google.com ([74.125.82.172]:46583 "EHLO mail-we0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750961AbaFRO6c (ORCPT ); Wed, 18 Jun 2014 10:58:32 -0400 Received: by mail-we0-f172.google.com with SMTP id u57so1024086wes.3 for ; Wed, 18 Jun 2014 07:58:30 -0700 (PDT) In-Reply-To: <20140618105120.GI14030@stefanha-thinkpad.redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 06/18/2014 12:51 PM, Stefan Hajnoczi wrote: >> >> Actually, you can avoid this memory copy using frameworks like DPDK. > > I guess it's careful to allocate all packets in the mmapped BAR? Yes. > That's fine if you can modify applications but doesn't work for > unmodified applications using regular networking APIs. If you have access to source code, this should not be a problem. -- David Marchand From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:58850) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WxHJu-000129-RZ for qemu-devel@nongnu.org; Wed, 18 Jun 2014 10:58:46 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WxHJn-0005hd-Ce for qemu-devel@nongnu.org; Wed, 18 Jun 2014 10:58:38 -0400 Received: from mail-wi0-f177.google.com ([209.85.212.177]:49578) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WxHJn-0005g6-6U for qemu-devel@nongnu.org; Wed, 18 Jun 2014 10:58:31 -0400 Received: by mail-wi0-f177.google.com with SMTP id r20so1311465wiv.4 for ; Wed, 18 Jun 2014 07:58:30 -0700 (PDT) Message-ID: <53A1A911.9040407@6wind.com> Date: Wed, 18 Jun 2014 16:58:25 +0200 From: David Marchand MIME-Version: 1.0 References: <20140612094413.15e56938@nbschild1> <87vbs6qjhj.fsf_-_@blackfin.pond.sub.org> <5399CF09.8030803@6wind.com> <87ppidnqmy.fsf@blackfin.pond.sub.org> <539AC3E0.9090404@6wind.com> <539ACDE6.7020709@redhat.com> <539AFF7C.7090702@6wind.com> <539B064D.2050501@redhat.com> <53A00464.8090609@6wind.com> <20140618105120.GI14030@stefanha-thinkpad.redhat.com> In-Reply-To: <20140618105120.GI14030@stefanha-thinkpad.redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] Why I advise against using ivshmem List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Hajnoczi Cc: Henning Schild , Olivier MATZ , kvm , qemu-devel , Linux Virtualization , Paolo Bonzini , Vincent JARDIN , "thomas.monjalon@6wind.com" On 06/18/2014 12:51 PM, Stefan Hajnoczi wrote: >> >> Actually, you can avoid this memory copy using frameworks like DPDK. > > I guess it's careful to allocate all packets in the mmapped BAR? Yes. > That's fine if you can modify applications but doesn't work for > unmodified applications using regular networking APIs. If you have access to source code, this should not be a problem. -- David Marchand