From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e06smtp09.uk.ibm.com (e06smtp09.uk.ibm.com [195.75.94.105]) by dpdk.org (Postfix) with ESMTP id A6B285A62 for ; Thu, 21 Jan 2016 16:38:42 +0100 (CET) Received: from localhost by e06smtp09.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 21 Jan 2016 15:38:41 -0000 Received: from d06dlp03.portsmouth.uk.ibm.com (9.149.20.15) by e06smtp09.uk.ibm.com (192.168.101.139) with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted; Thu, 21 Jan 2016 15:38:38 -0000 X-IBM-Helo: d06dlp03.portsmouth.uk.ibm.com X-IBM-MailFrom: cornelia.huck@de.ibm.com X-IBM-RcptTo: dev@dpdk.org Received: from b06cxnps4075.portsmouth.uk.ibm.com (d06relay12.portsmouth.uk.ibm.com [9.149.109.197]) by d06dlp03.portsmouth.uk.ibm.com (Postfix) with ESMTP id 76B0C1B08067 for ; Thu, 21 Jan 2016 15:38:43 +0000 (GMT) Received: from d06av08.portsmouth.uk.ibm.com (d06av08.portsmouth.uk.ibm.com [9.149.37.249]) by b06cxnps4075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id u0LFcc8w3146142 for ; Thu, 21 Jan 2016 15:38:38 GMT Received: from d06av08.portsmouth.uk.ibm.com (localhost [127.0.0.1]) by d06av08.portsmouth.uk.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id u0LFccZs003396 for ; Thu, 21 Jan 2016 08:38:38 -0700 Received: from gondolin (dyn-9-152-224-197.boeblingen.de.ibm.com [9.152.224.197]) by d06av08.portsmouth.uk.ibm.com (8.14.4/8.14.4/NCO v10.0 AVin) with ESMTP id u0LFcbS7003383; Thu, 21 Jan 2016 08:38:37 -0700 Date: Thu, 21 Jan 2016 16:38:36 +0100 From: Cornelia Huck To: "Michael S. Tsirkin" Message-ID: <20160121163836.1091943d.cornelia.huck@de.ibm.com> In-Reply-To: <20160121145418-mutt-send-email-mst@redhat.com> References: <20160121145418-mutt-send-email-mst@redhat.com> Organization: IBM Deutschland Research & Development GmbH Vorsitzende des Aufsichtsrats: Martina Koederitz =?UTF-8?B?R2VzY2jDpGZ0c2bDvGhydW5nOg==?= Dirk Wittkopp Sitz der Gesellschaft: =?UTF-8?B?QsO2Ymxpbmdlbg==?= Registergericht: Amtsgericht Stuttgart, HRB 243294 X-Mailer: Claws Mail 3.8.0 (GTK+ 2.24.10; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16012115-0037-0000-0000-000005569C36 X-Mailman-Approved-At: Thu, 21 Jan 2016 20:21:48 +0100 Cc: virtio-dev@lists.oasis-open.org, kvm@vger.kernel.org, dev@dpdk.org, linux-kernel@vger.kernel.org, qemu-devel@nongnu.org, virtio@lists.oasis-open.org, virtualization@lists.linux-foundation.org Subject: Re: [dpdk-dev] virtio ring layout changes for optimal single-stream performance X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 21 Jan 2016 15:38:43 -0000 On Thu, 21 Jan 2016 15:39:26 +0200 "Michael S. Tsirkin" wrote: > Hi all! > I have been experimenting with alternative virtio ring layouts, > in order to speed up single stream performance. > > I have just posted a benchmark I wrote for the purpose, and a (partial) > alternative layout implementation. This achieves 20-40% reduction in > virtio overhead in the (default) polling mode. > > http://article.gmane.org/gmane.linux.kernel.virtualization/26889 > > The layout is trying to be as simple as possible, to reduce > the number of cache lines bouncing between CPUs. Some kind of diagram or textual description would really help to review this. > > For benchmarking, the idea is to emulate virtio in user-space, > artificially adding overhead for e.g. signalling to match what happens > in case of a VM. Hm... is this overhead comparable enough between different platform so that you can get a halfway realistic scenario? What about things like endianness conversions? > > I'd be very curious to get feedback on this, in particular, some people > discussed using vectored operations to format virtio ring - would it > conflict with this work? > > You are all welcome to post enhancements or more layout alternatives as > patches. Let me see if I can find time to experiment a bit.