From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gleb Natapov Subject: Re: vhost + multiqueue + RSS question. Date: Mon, 17 Nov 2014 09:26:18 +0200 Message-ID: <20141117072618.GE7589@cloudius-systems.com> References: <20141116161818.GD7589@cloudius-systems.com> <20141116185604.GA12839@redhat.com> <546987DE.2010701@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "Michael S. Tsirkin" , kvm@vger.kernel.org, virtualization@lists.linux-foundation.org To: Jason Wang Return-path: Received: from mail-wi0-f175.google.com ([209.85.212.175]:45613 "EHLO mail-wi0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751049AbaKQH0Y (ORCPT ); Mon, 17 Nov 2014 02:26:24 -0500 Received: by mail-wi0-f175.google.com with SMTP id l15so4763038wiw.2 for ; Sun, 16 Nov 2014 23:26:23 -0800 (PST) Content-Disposition: inline In-Reply-To: <546987DE.2010701@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On Mon, Nov 17, 2014 at 01:30:06PM +0800, Jason Wang wrote: > On 11/17/2014 02:56 AM, Michael S. Tsirkin wrote: > > On Sun, Nov 16, 2014 at 06:18:18PM +0200, Gleb Natapov wrote: > >> Hi Michael, > >> > >> I am playing with vhost multiqueue capability and have a question about > >> vhost multiqueue and RSS (receive side steering). My setup has Mellanox > >> ConnectX-3 NIC which supports multiqueue and RSS. Network related > >> parameters for qemu are: > >> > >> -netdev tap,id=hn0,script=qemu-ifup.sh,vhost=on,queues=4 > >> -device virtio-net-pci,netdev=hn0,id=nic1,mq=on,vectors=10 > >> > >> In a guest I ran "ethtool -L eth0 combined 4" to enable multiqueue. > >> > >> I am running one tcp stream into the guest using iperf. Since there is > >> only one tcp stream I expect it to be handled by one queue only but > >> this seams to be not the case. ethtool -S on a host shows that the > >> stream is handled by one queue in the NIC, just like I would expect, > >> but in a guest all 4 virtio-input interrupt are incremented. Am I > >> missing any configuration? > > I don't see anything obviously wrong with what you describe. > > Maybe, somehow, same irqfd got bound to multiple MSI vectors? > > To see, can you try dumping struct kvm_irqfd that's passed to kvm? > > > > > >> -- > >> Gleb. > > This sounds like a regression, which kernel/qemu version did you use? Sorry, should have mentioned it from the start. Host is a fedora 20 with kernel 3.16.6-200.fc20.x86_64 and qemu-system-x86-1.6.2-9.fc20.x86_64. Guest is also fedora 20 but with an older kernel 3.11.10-301. -- Gleb.