From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Hutchings Subject: Re: [PATCH v2] net: Allow ethtool to set interface in loopback mode. Date: Thu, 06 Jan 2011 22:13:31 +0000 Message-ID: <1294352011.11825.50.camel@bwh-desktop> References: <1294187401-4662-1-git-send-email-maheshb@google.com> <20110104163645.0b3a3687@nehalam> <1294190504.2992.3.camel@localhost> <4D249ABD.4080209@garzik.org> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: Stephen Hemminger , Mahesh Bandewar , David Miller , Laurent Chavey , Tom Herbert , netdev To: Jeff Garzik Return-path: Received: from mail.solarflare.com ([216.237.3.220]:15982 "EHLO exchange.solarflare.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754355Ab1AFWNf (ORCPT ); Thu, 6 Jan 2011 17:13:35 -0500 In-Reply-To: <4D249ABD.4080209@garzik.org> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, 2011-01-05 at 11:22 -0500, Jeff Garzik wrote: > 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. Well, that would allow the patch to be simplified quite a bit. :-) Ben. From: Ben Hutchings Subject: [PATCH net-2.6] ethtool: Define ETH_FLAG_LOOPBACK Date: Thu, 6 Jan 2011 22:10:55 +0000 Mahesh Bandewar requested this, writing: 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. Signed-off-by: Ben Hutchings --- a/include/linux/ethtool.h +++ b/include/linux/ethtool.h @@ -309,6 +309,7 @@ struct ethtool_perm_addr { * flag differs from the read-only value. */ enum ethtool_flags { + ETH_FLAG_LOOPBACK = (1 << 2), /* Host-side loopback enabled */ ETH_FLAG_TXVLAN = (1 << 7), /* TX VLAN offload enabled */ ETH_FLAG_RXVLAN = (1 << 8), /* RX VLAN offload enabled */ ETH_FLAG_LRO = (1 << 15), /* LRO is enabled */ --- -- Ben Hutchings, Senior Software Engineer, Solarflare Communications Not speaking for my employer; that's the marketing department's job. They asked us to note that Solarflare product names are trademarked.