From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gregory Haskins Subject: Re: Bandwith limitation with KVM VMs Date: Mon, 03 Aug 2009 12:52:28 -0400 Message-ID: <4A7715CC.7030901@gmail.com> References: <20090803163205.GJ23503@defiant.freesoftware.org> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig3756CA95EDF8E21783491645" To: dbareiro@gmx.net, KVM General Return-path: Received: from mail-pz0-f196.google.com ([209.85.222.196]:44385 "EHLO mail-pz0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751971AbZHCQwc (ORCPT ); Mon, 3 Aug 2009 12:52:32 -0400 Received: by pzk34 with SMTP id 34so2521944pzk.4 for ; Mon, 03 Aug 2009 09:52:32 -0700 (PDT) In-Reply-To: <20090803163205.GJ23503@defiant.freesoftware.org> Sender: kvm-owner@vger.kernel.org List-ID: This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig3756CA95EDF8E21783491645 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Daniel Bareiro wrote: > Hi all! >=20 > I have a KVM VM that it has installed a MRTG on the network interface > and that it doesn't register more than 10 Mbps, seeming that per moment= s > it is saturated in this value. >=20 > Has KVM some bandwidth limitation of the virtualized network interfaces= ? > In such case, exists some way to increase that limitation? >=20 There is no set artificial limit afaict, though there are a large number of factors that can affect performance. Of course, everything has an ultimate ceiling (KVM included) but I have found this limit in KVM to be orders of magnitude faster than 10Mbps. Properly tuned, you should easily be able to saturate a GE link at line rate, or even 4Gbps-5Gpbs of a 10GE link. If you need even more than that, I would suggest taking a look at my recently announced project which focuses on IO performance: http://developer.novell.com/wiki/index.php/AlacrityVM However, since you are only hitting 10Mb/s now, there is ton of headroom left even on upstream KVM so you might find it to be satisfactory as is, once you address the current bottleneck in your setup. Things to check: What linkspeed does the host see to the next hop? How much bandwidth does the host see to the same end-point? What is your overall topology, especially for the VM (are you using -net tap, etc). What MTU are you using. Etc. Good luck! -Greg --------------enig3756CA95EDF8E21783491645 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/ iEYEARECAAYFAkp3FcwACgkQP5K2CMvXmqH34gCfY/47lP10cuJlckZTt/bIhHgo nCEAniydS4W3TYYb8NztJQRYcikkFCG4 =z+Gs -----END PGP SIGNATURE----- --------------enig3756CA95EDF8E21783491645--