From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: [PATCH v2] net: Allow ethtool to set interface in loopback mode. Date: Wed, 05 Jan 2011 11:22:21 -0500 Message-ID: <4D249ABD.4080209@garzik.org> 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=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: Stephen Hemminger , Mahesh Bandewar , David Miller , Laurent Chavey , Tom Herbert , netdev To: Ben Hutchings Return-path: Received: from mail-qy0-f181.google.com ([209.85.216.181]:32841 "EHLO mail-qy0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751245Ab1AEQW2 (ORCPT ); Wed, 5 Jan 2011 11:22:28 -0500 Received: by qyk12 with SMTP id 12so17533153qyk.19 for ; Wed, 05 Jan 2011 08:22:27 -0800 (PST) In-Reply-To: <1294190504.2992.3.camel@localhost> Sender: netdev-owner@vger.kernel.org List-ID: On 01/04/2011 08:21 PM, 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 doesn't have to be. As Stephen guessed, [GS]FLAGS are basically common flags -- as differentiated from private, driver-specific/hardware-specific flags. Jeff