From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:46288) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TVLLA-0001VH-Fg for qemu-devel@nongnu.org; Mon, 05 Nov 2012 06:59:41 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TVLL9-0001qf-FN for qemu-devel@nongnu.org; Mon, 05 Nov 2012 06:59:40 -0500 Received: from www.maurer-it.com ([213.129.239.114]:38910 helo=proxmox.maurer-it.com) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TVLL9-0001qZ-9B for qemu-devel@nongnu.org; Mon, 05 Nov 2012 06:59:39 -0500 Received: from proxmox.maurer-it.com (localhost.localdomain [127.0.0.1]) by proxmox.maurer-it.com (Proxmox) with ESMTP id 7ACAD26A0912 for ; Mon, 5 Nov 2012 12:51:16 +0100 (CET) From: Dietmar Maurer Date: Mon, 5 Nov 2012 11:51:15 +0000 Message-ID: <24E144B8C0207547AD09C467A8259F75577D5BE5@lisa.maurer-it.com> Content-Language: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Subject: [Qemu-devel] slow virtio network with vhost=on and multiple cores List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "qemu-devel@nongnu.org" Network performance with vhost=3Don is extremely bad if a guest uses multip= le cores: HOST kernel: RHEL 2.6.32-279.11.1.el6 KVM 1.2.0 GuestOS: Debian Squeeze (amd64 or 686), CentOS 6.2 Test with something like (install Debian Squeeze first): ./x86_64-softmmu/qemu-system-x86_64 -smp sockets=3D1,cores=3D2 -m 512 -hda = debian-squeeze-netinst.raw -netdev type=3Dtap,id=3Dnet0,ifname=3Dtap111i0,v= host=3Don -device virtio-net-pci,netdev=3Dnet0,id=3Dnet0 Downloading a larger file with wget inside the guest will show the problem.= Speed drops from 100MB/s to 15MB/s. Can someone reproduce that bug? Any ideas how to fix that? - Dietmar=20