From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ingo Molnar Subject: Re: [PATCH v2 00/31] Implement user mode network for kvm tools Date: Sun, 3 Jul 2011 21:42:15 +0200 Message-ID: <20110703194215.GA27022@elte.hu> References: <1309423279-3093-1-git-send-email-asias.hejun@gmail.com> <4E0C96FF.4090801@codemonkey.ws> <4E0D1238.3020506@gmail.com> <20110701115308.GJ20990@elte.hu> <27C3F9A0-8814-41A4-A45E-05A9B57DC139@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Asias He , Anthony Liguori , Stefan Hajnoczi , Pekka Enberg , Cyrill Gorcunov , Sasha Levin , Prasad Joshi , kvm@vger.kernel.org To: Alexander Graf Return-path: Received: from mx3.mail.elte.hu ([157.181.1.138]:43887 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752284Ab1GCTmX (ORCPT ); Sun, 3 Jul 2011 15:42:23 -0400 Content-Disposition: inline In-Reply-To: <27C3F9A0-8814-41A4-A45E-05A9B57DC139@suse.de> Sender: kvm-owner@vger.kernel.org List-ID: * Alexander Graf wrote: > > That's pretty impressive (if it does not come at the expensive of > > features that Qemu's slirp code has) - and the thing is that we > > don't actually have to implement the vast majority of TCP-IP > > features, because the transport between the guest and the host is > > obviously reliable. > > I don't see how it would. Once you overrun device buffers, you have > to do something. Either you drop packets or you stall the guest. > I'd usually prefer the former :). What scenario do you see where we'd have to drop packets? When the guest sends packets, we send them over to the host TCP socket - no blocking. When the host receives packets it should only read data out of the host socket(s) if the vring buffer suggests that there's space available. So i don't see we'd need to drop packets or block things - we just have to react to packets and to vring space availability in a straightforward way. Thanks, Ingo