From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: [RFT] IRQ sharing for assigned devices - method selection Date: Fri, 07 Jan 2011 10:33:12 +0100 Message-ID: <4D26DDD8.5040707@web.de> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig816D95E8D9044DEFE90BDC11" Cc: Alex Williamson , "Michael S. Tsirkin" , Avi Kivity To: kvm Return-path: Received: from fmmailgate02.web.de ([217.72.192.227]:53161 "EHLO fmmailgate02.web.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752337Ab1AGJeF (ORCPT ); Fri, 7 Jan 2011 04:34:05 -0500 Sender: kvm-owner@vger.kernel.org List-ID: This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig816D95E8D9044DEFE90BDC11 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: quoted-printable Hi, to finally select the approach for adding overdue IRQ sharing support for PCI pass-through, I hacked up two versions based on Thomas' patches and his suggestion to use a timeout-based mode transition: git://git.kiszka.org/linux-kvm.git queues/dev-assign.notify git://git.kiszka.org/linux-kvm.git queues/dev-assign.timeout git://git.kiszka.org/qemu-kvm.git queues/dev-assign Both approaches work, but I'm either lacking a sufficiently stressing test environment to tickle out a relevant delta, even between masking at irqchip vs. PCI config space level - or there is none... Yes, there are differences at micro level but they do not manifest in measurable (ie. above the noise level) load increase or throughput/latency decrease in my limited tests here. I that actually turns out to be true, I would happily bury all this dynamic mode switching again. So, if you have a good high-bandwidth test case at hand, I would appreciate if you could give this a try and report your findings. Does switching from exclusive to shared IRQ mode decrease the throughput or increase the host load? Is there a difference to current kvm? Thanks in advance, Jan --------------enig816D95E8D9044DEFE90BDC11 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.15 (GNU/Linux) Comment: Using GnuPG with SUSE - http://enigmail.mozdev.org/ iEYEARECAAYFAk0m3dgACgkQitSsb3rl5xRIEQCePJzjjNcuVleA/G7G2/Q/3k/w bB0AoMVUWhxEX6sDWhnYDwMnPpxaqyiA =lSZQ -----END PGP SIGNATURE----- --------------enig816D95E8D9044DEFE90BDC11--