From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: Remaining passthrough/VT-d tasks list Date: Wed, 24 Sep 2008 12:22:53 +0300 Message-ID: <48DA06ED.9090605@redhat.com> References: <0122C7C995D32147B66BF4F440D3016301C49E61@pdsmsx415.ccr.corp.intel.com> <200809241642.54667.sheng.yang@intel.com> <48D9FFFB.5040505@redhat.com> <200809241708.31835.sheng.yang@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: "Han, Weidong" , "kvm@vger.kernel.org" , Amit Shah , "benami@il.ibm.com" , "muli@il.ibm.com" , "Kay, Allen M" , "Zhang, Xiantao" To: "Yang, Sheng" Return-path: Received: from mx2.redhat.com ([66.187.237.31]:44192 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751234AbYIXJYG (ORCPT ); Wed, 24 Sep 2008 05:24:06 -0400 In-Reply-To: <200809241708.31835.sheng.yang@intel.com> Sender: kvm-owner@vger.kernel.org List-ID: Yang, Sheng wrote: >> We only have three pci interrupts at this point (though this could be >> easily extended); if you start the guest with a non-trivial number of >> devices, you will have shared guest interrupts. >> >> (of course, when I pointed this out during review, people said it could >> be done later, then forgot all about it) >> >> > ..... > > I think it's a performance issue, not break it? How about do it like Xen side? > Try best to avoid the share, extended the pci interrupts, improve hash > algorithm. Is there anything else we can do? > Two separate issues: 1. only three guest pci interrupts That's a performance issue, not correctness. can be fixed by using gsi 16-23 in APIC mode, and by adding another IOAPIC (so we can use gsi 16-47). Anthony Xu posted some patches for this, not sure where this stands, but it was the right approach. 2. shared guest pci interrupts That's a correctness issue. No matter how many interrupts we have, we may have sharing issues. Of course with only three the issue is very pressing since we will get sharing with just a few devices. Currently if two assigned devices share a guest interrupts, or if an emulated device shares an interrupt with an assigned device, things will break. They need to be fixed independently. -- error compiling committee.c: too many arguments to function