From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH 0/2] eventfd: new EFD_STATE flag Date: Thu, 20 Aug 2009 20:55:41 +0300 Message-ID: <20090820175540.GA9232@redhat.com> References: <20090820155655.GA8764@redhat.com> <4A8D8A28.2050004@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Davide Libenzi , gleb@redhat.com, kvm@vger.kernel.org, Linux Kernel Mailing List To: Avi Kivity Return-path: Content-Disposition: inline In-Reply-To: <4A8D8A28.2050004@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On Thu, Aug 20, 2009 at 08:38:48PM +0300, Avi Kivity wrote: > On 08/20/2009 07:20 PM, Davide Libenzi wrote: >> >> I briefly looked at this while in vacation, although I did not reply >> hoping the horrible feeling about this code would go away. >> It didn't. >> I find this to be an ugly and ad-hoc multiplexing of eventfd with added >> functionalities of questionable general use. >> I'm pretty sure you can do better on KVM side, to solve the problem w/out >> littering eventfd. >> >> > > While we could argue about this my feeling is that we should drop this, > at least until we can quantify what benefit it has and whether there are > any Davide-acceptable alternatives. > > In the meanwhile, we can let vhost-net support edge-triggered interrupts > only, let qemu terminate those eventfds and convert then to > level-triggered interrupts (which it can then inject using the existing > ioctl). It will keep vhost-net and kvm simpler at the cost of some > performance penalty to guests using level interrupts. These suck anyway > so we'll point users at msi. I thought the point was to move assigned devices out of KVM? > -- > I have a truly marvellous patch that fixes the bug which thisb > signature is too narrow to contain.