From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH v4] kvm: Use a bitmap for tracking used GSIs Date: Wed, 13 May 2009 16:00:03 +0300 Message-ID: <4A0AC453.2000907@redhat.com> References: <20090512220142.5663.72948.stgit@dl380g6-3.ned.telco.ned.telco> <20090513043835.6696.27384.stgit@dl380g6-3.ned.telco.ned.telco> <4A0A973A.9020502@redhat.com> <1242217702.4786.59.camel@2710p.home> <4A0ABEA8.6030103@redhat.com> <1242219343.4786.66.camel@2710p.home> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, sheng.yang@intel.com, mst@redhat.com To: Alex Williamson Return-path: Received: from mx2.redhat.com ([66.187.237.31]:44777 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757972AbZEMNAE (ORCPT ); Wed, 13 May 2009 09:00:04 -0400 In-Reply-To: <1242219343.4786.66.camel@2710p.home> Sender: kvm-owner@vger.kernel.org List-ID: Alex Williamson wrote: >> >> When you say "multiple times", it is several, or a lot more? >> >> Maybe it is NAPI? >> > > The system would run out of the ~1000 available GSIs in a minute or two > with just an e1000e available to the guest. So that's something on the > order of 10/s. This also causes a printk in the host ever time the > interrupt in enabled, which can't help performance and gets pretty > annoying for syslog. I was guessing some kind of interrupt mitigation, > such as NAPI, but a qlogic FC card seems to do it too (seemingly at a > slower rate). > I see. And what is the path by which it is disabled? The mask bit in the MSI entry? -- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain.