From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: [PATCH v2] net: Allow ethtool to set interface in loopback mode. Date: Tue, 4 Jan 2011 17:29:39 -0800 Message-ID: <20110104172939.711b758d@nehalam> References: <1294187401-4662-1-git-send-email-maheshb@google.com> <20110104163645.0b3a3687@nehalam> <1294190504.2992.3.camel@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Mahesh Bandewar , David Miller , Laurent Chavey , Tom Herbert , netdev To: Ben Hutchings Return-path: Received: from mail.vyatta.com ([76.74.103.46]:45656 "EHLO mail.vyatta.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751163Ab1AEB3o (ORCPT ); Tue, 4 Jan 2011 20:29:44 -0500 In-Reply-To: <1294190504.2992.3.camel@localhost> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, 05 Jan 2011 01:21:44 +0000 Ben Hutchings wrote: > On Tue, 2011-01-04 at 16:36 -0800, Stephen Hemminger wrote: > > On Tue, 4 Jan 2011 16:30:01 -0800 > > Mahesh Bandewar wrote: > > > > > This patch enables ethtool to set the loopback mode on a given interface. > > > By configuring the interface in loopback mode in conjunction with a policy > > > route / rule, a userland application can stress the egress / ingress path > > > exposing the flows of the change in progress and potentially help developer(s) > > > understand the impact of those changes without even sending a packet out > > > on the network. > > > > > > Following set of commands illustrates one such example - > > > a) ip -4 addr add 192.168.1.1/24 dev eth1 > > > b) ip -4 rule add from all iif eth1 lookup 250 > > > c) ip -4 route add local 0/0 dev lo proto kernel scope host table 250 > > > d) arp -Ds 192.168.1.100 eth1 > > > e) arp -Ds 192.168.1.200 eth1 > > > f) sysctl -w net.ipv4.ip_nonlocal_bind=1 > > > g) sysctl -w net.ipv4.conf.all.accept_local=1 > > > # Assuming that the machine has 8 cores > > > h) taskset 000f netserver -L 192.168.1.200 > > > i) taskset 00f0 netperf -t TCP_CRR -L 192.168.1.100 -H 192.168.1.200 -l 30 > > > > > > Signed-off-by: Mahesh Bandewar > > > Reviewed-by: Ben Hutchings > > > > Since this is a boolean it SHOULD go into ethtool_flags rather than > > being a high level operation. > > It could do, but I though ETHTOOL_{G,S}FLAGS were intended for > controlling offload features. It just seems the number of hooks keeps growing which takes more space and increases complexity. There was some talk about changing GRO/TSO/UFO .. to be bits in FLAGS but not sure how far along that is. --