From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:60292) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TWOa6-00052C-2k for qemu-devel@nongnu.org; Thu, 08 Nov 2012 04:39:27 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TWOa4-0008QZ-UW for qemu-devel@nongnu.org; Thu, 08 Nov 2012 04:39:26 -0500 Received: from mout.web.de ([212.227.17.12]:58619) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TWOa4-0008QG-Ip for qemu-devel@nongnu.org; Thu, 08 Nov 2012 04:39:24 -0500 Message-ID: <509B7DC4.3010802@web.de> Date: Thu, 08 Nov 2012 10:39:16 +0100 From: Jan Kiszka MIME-Version: 1.0 References: <24E144B8C0207547AD09C467A8259F75577D5BE5@lisa.maurer-it.com> <24E144B8C0207547AD09C467A8259F75577E90B9@lisa.maurer-it.com> <24E144B8C0207547AD09C467A8259F75577EC2E1@lisa.maurer-it.com> <5098D7B9.9020205@web.de> <24E144B8C0207547AD09C467A8259F75577EC39A@lisa.maurer-it.com> <5098E288.9060505@web.de> <24E144B8C0207547AD09C467A8259F75577EC4B2@lisa.maurer-it.com> In-Reply-To: <24E144B8C0207547AD09C467A8259F75577EC4B2@lisa.maurer-it.com> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig3DC7E927ED0F5BB417DF0DD3" Subject: Re: [Qemu-devel] slow virtio network with vhost=on and multiple cores List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Dietmar Maurer Cc: Stefan Hajnoczi , Peter Lieven , "qemu-devel@nongnu.org" , "Michael S. Tsirkin" This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig3DC7E927ED0F5BB417DF0DD3 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On 2012-11-06 12:24, Dietmar Maurer wrote: >> On 2012-11-06 10:46, Dietmar Maurer wrote: >>>>> This obviously breaks vhost when using multiple cores. >>>> >>>> With "obviously" you mean you already have a clue why? >>>> >>>> I'll try to reproduce. >>> >>> No, sorry - just meant the performance regression is obvious (factor = 20 to >> 40). >>> >> >> OK. Did you try to bisect over qemu-kvm as well? >=20 > No (I thought that is the same code base?) Already answered, though accidentally in private only: it is the same code base now, but qemu-kvm has a different history and may contain versions that didn't suffer from the issue. Meanwhile I quickly tried to reproduce but didn't succeed so far (>10GBit between host and guest with vhost=3Don and 2 guest cores). However, I finally realized that we are talking about a pretty special host kernel which I don't have around. I guess this is better dealt with by Red Hat folks. Specifically, they should know what features that kernel exposes and what it lacks. Jan --------------enig3DC7E927ED0F5BB417DF0DD3 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.16 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://www.enigmail.net/ iEYEARECAAYFAlCbfcgACgkQitSsb3rl5xRHJQCg7rWzmEDVXu5GdTn84h09nElS POkAoMUxV4kOefUcLXP5nCL1XCDI5E3G =ZtSJ -----END PGP SIGNATURE----- --------------enig3DC7E927ED0F5BB417DF0DD3--