From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [RFC][PATCH 1/2] kvm: Introduce basic MSI support in-kernel irqchips Date: Wed, 28 Mar 2012 13:44:41 +0200 Message-ID: <4F72F9A9.6000700@redhat.com> References: <865ef757142e5b9a670dfc9bcd8eb0ff7ab5d58b.1332371825.git.jan.kiszka@web.de> <4F72F165.8020009@redhat.com> <4F72F6F5.5020202@siemens.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Marcelo Tosatti , kvm@vger.kernel.org, qemu-devel , "Michael S. Tsirkin" To: Jan Kiszka Return-path: Received: from mx1.redhat.com ([209.132.183.28]:62104 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752648Ab2C1Los (ORCPT ); Wed, 28 Mar 2012 07:44:48 -0400 In-Reply-To: <4F72F6F5.5020202@siemens.com> Sender: kvm-owner@vger.kernel.org List-ID: On 03/28/2012 01:33 PM, Jan Kiszka wrote: > On 2012-03-28 13:09, Avi Kivity wrote: > > On 03/22/2012 01:17 AM, Jan Kiszka wrote: > >> From: Jan Kiszka > >> > >> This patch basically adds kvm_irqchip_send_msi, a service for sending > >> arbitrary MSI messages to KVM's in-kernel irqchip models. > >> > >> As the current KVI API requires us to establish a static route from a > > > > s/KVI/KVM/ > > > >> pseudo GSI to the target MSI message and inject the MSI via toggling > >> that GSI, we need to play some tricks to make this unfortunately > > > > s/unfortunately/unfortunate/ > > Will fix these. Only needed if you end up reposting. > > > >> interface transparent. We create those routes on demand and keep them > >> in a hash table. Succeeding messages can then search for an existing > >> route in the table first and reuse it whenever possible. If we should > >> run out of limited GSIs, we simply flush the table and rebuild it as > >> messages are sent. > >> > >> This approach is rather simple and could be optimized further. However, > >> it is more efficient to enhance the KVM API so that we do not need this > >> clumsy dynamic routing over futures kernels. > > > > Two APIs are clumsier than one. > > The current one is very clumsy for user-injected MSIs while the new one > won't be. It will also be very simple it implement if you recall the > patch. I think that is worth it. Don't see why. The clumsiness will be retained. The cpu doesn't care how clumsy the API is, only the reader. > > > > > wet the patch itself, suggest replacing the home grown hash with > > http://developer.gnome.org/glib/2.30/glib-Caches.html. > > Let's keep it simple :). We have no need for many of those features, and > it would not be possible to implement the logic as compact as it is > right now. Due to the callbacks? What if the code grows? -- error compiling committee.c: too many arguments to function