From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: [RFC] Kernel Control Path (KCP) Date: Fri, 16 Jun 2017 09:48:33 -0700 Message-ID: <20170616094833.701cfb28@xeon-e3> References: <20170526165228.96919-1-ferruh.yigit@intel.com> <3497879.P1UMQ6Rz4g@xps> <3EB4FA525960D640B5BDFFD6A3D891267BA69B98@IRSMSX108.ger.corp.intel.com> <7879b121-fca9-995a-0087-12c840fbc47e@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Alex Rosenbaum , "Wiles, Keith" , "Dumitrescu, Cristian" , Jay Rolette , Thomas Monjalon , DPDK To: Ferruh Yigit Return-path: Received: from mail-pf0-f173.google.com (mail-pf0-f173.google.com [209.85.192.173]) by dpdk.org (Postfix) with ESMTP id 36BF22BD1 for ; Fri, 16 Jun 2017 18:48:42 +0200 (CEST) Received: by mail-pf0-f173.google.com with SMTP id x63so24791334pff.3 for ; Fri, 16 Jun 2017 09:48:42 -0700 (PDT) In-Reply-To: <7879b121-fca9-995a-0087-12c840fbc47e@intel.com> List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On Fri, 16 Jun 2017 16:27:47 +0100 Ferruh Yigit wrote: > Hi Alex, > > On 6/15/2017 1:07 PM, Alex Rosenbaum wrote: > > please excuse me if I missed out of the previous conversation and > > asking these questions again... > > > > Why create a new driver instead of improving the existing KNI driver? > > For control path, KNI uses Linux kernel driver within KNI kernel module. > This method works, but may not be best option, and technically not > extendable for some drivers. KNI control path currently supports only > two drivers, proposed KCP works for all PMDs by default. > > Overall, KCP is outcome of the effort of improving KNI control path. > > Initial proposal was (a year ago I guess) introducing two new modules, > one for control path and one for data path, and replace KNI completely. > But current target is have KCP to have better control path support. > > Also, KNI handles both data and control path. But both are different > functionalities and not need to be in some module. For example an > application may not need exception data path to kernel, but may be > interested in controlling DPDK interfaces via common Linux tools. > > > Can you share a table of the differences between the two driver / > > approaches [KNI vs KCP]? > > KCP differences against KNI: > > - KCP is only for control path > - Linux virtual interfaces created automatically, without DPDK > application modification. > - To create/destroy interfaces KCP uses rtnl, KNI uses ioctl. So > technically it is possible to use "ip" tool to create / destroy > interfaces supported by KCP. > - KCP kernel module and userspace counterpart communicates via netlink, > KNI uses ioctl. > - KCP works for all PMDs without update on PMDs. > > > > > Why do you want to remove features like data path that is provided by KNI today? > > There is not intention to remove exception data path, the focus is to > improve KNI. > > > > > thanks, > > Alex > > > Hopefully KCP can be submitted for upstream kernel, and therefore be supportable over the long term. KNI in its current form is not acceptable upstream for a number of reasons: style, use of ioctl, races with control operations, etc.