From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761588AbZE0Rke (ORCPT ); Wed, 27 May 2009 13:40:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758971AbZE0RkZ (ORCPT ); Wed, 27 May 2009 13:40:25 -0400 Received: from victor.provo.novell.com ([137.65.250.26]:42464 "EHLO victor.provo.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760469AbZE0RkX (ORCPT ); Wed, 27 May 2009 13:40:23 -0400 Message-ID: <4A1D7AFD.40004@novell.com> Date: Wed, 27 May 2009 13:40:13 -0400 From: Gregory Haskins User-Agent: Thunderbird 2.0.0.21 (Macintosh/20090302) MIME-Version: 1.0 To: Mark McLoughlin CC: Avi Kivity , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Davide Libenzi , mtosatti@redhat.com Subject: Re: [KVM PATCH v4 3/3] kvm: add iosignalfd support References: <20090526191010.20860.75372.stgit@dev.haskins.net> <20090526191539.20860.1385.stgit@dev.haskins.net> <4A1D01F8.8080508@redhat.com> <4A1D285C.9050008@novell.com> <4A1D2DD8.2050709@redhat.com> <1243445144.16318.15.camel@blaa> In-Reply-To: <1243445144.16318.15.camel@blaa> X-Enigmail-Version: 0.95.7 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig14254BC946717CCE5FEC045F" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig14254BC946717CCE5FEC045F Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Mark McLoughlin wrote: > On Wed, 2009-05-27 at 15:11 +0300, Avi Kivity wrote: > > =20 >> Multiple cookies on the same address are required by virtio. You can'= t=20 >> mux since the data doesn't go anywhere. >> >> Virtio can survive by checking all rings on a notify, and we can later= =20 >> add a mechanism that has a distinct address for each ring, but let's s= ee=20 >> if we can cope with multiple cookies. Mark? >> =20 > > Trying to catch up, but you're talking about replacing virtio-pci > QUEUE_NOTIFY handling with iosignalfd ? > > For a perfect replacement, what you really need is to be able to > register multiple cookies per address range, but only have them trigger= > if the written data matches a provided value. > =20 Hmm..thats an interesting idea. To date, the "cookie" has really been for identifying the proper range selected for deassignment. I never thought of using it as an actual trigger value at run-time. > If the data is lost, virtio has no way of knowing which queue is being > notified, so we either end up with per-device, rather than per-queue, > notifications (probably not too bad for net, at least) or a different > notify address per queue (limiting the number of queues per device). > =20 The addr-per-queue is how I was envisioning it, but the trigger value concept hadn't occurred to me. I could make this an option during assignment (e.g. "COOKIE" flag means only trigger on writes of the provided cookie, otherwise trigger on any write). Sound good? Thanks Mark, -Greg --------------enig14254BC946717CCE5FEC045F Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG/MacGPG2 v2.0.11 (Darwin) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iEYEARECAAYFAkodewAACgkQlOSOBdgZUxnBrACeMUoZEoIaIDGBzRkJW+44v6at +18An1ikOi+GgoLkoob104UtA58RHnOY =j0VY -----END PGP SIGNATURE----- --------------enig14254BC946717CCE5FEC045F--