From mboxrd@z Thu Jan 1 00:00:00 1970 From: jamal Subject: Re: [e1000]: flow control on by default - good idea really? Date: Thu, 06 Jul 2006 23:09:18 -0400 Message-ID: <1152241758.5341.9.camel@jzny2> References: <1152033116.5276.22.camel@jzny2> <1152040839.5276.25.camel@jzny2> <20060705.112237.41652489.davem@davemloft.net> <44AC05A8.9030503@intel.com> <1152191018.5103.48.camel@jzny2> <44AD55B2.3030900@intel.com> Reply-To: hadi@cyberus.ca Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: David Miller , netdev@vger.kernel.org, jesse.brandeburg@intel.com, Robert.Olsson@data.slu.se, john.ronciak@intel.com, greearb@candelatech.com, jgarzik@pobox.com, Krzysztof Oledzki Return-path: Received: from mx03.cybersurf.com ([209.197.145.106]:57742 "EHLO mx03.cybersurf.com") by vger.kernel.org with ESMTP id S1751159AbWGGDJY (ORCPT ); Thu, 6 Jul 2006 23:09:24 -0400 Received: from mail.cyberus.ca ([209.197.145.21]) by mx03.cybersurf.com with esmtp (Exim 4.30) id 1Fygih-00056e-Fc for netdev@vger.kernel.org; Thu, 06 Jul 2006 23:09:31 -0400 To: Auke Kok In-Reply-To: <44AD55B2.3030900@intel.com> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Thu, 2006-06-07 at 11:25 -0700, Auke Kok wrote: > jamal wrote: > > hadi@jzny2:~/Desktop/maemo$ sudo ethtool -a eth0 > > Pause parameters for eth0: > > Autonegotiate: on > > RX: off > > TX: off > > mine says it's on :) Dell D610: hadi@jzny2:~$ sudo lspci | grep -i bcm 0000:02:00.0 Ethernet controller: Broadcom Corporation NetXtreme BCM5751 Gigabit Ethernet PCI Express (rev 01) Whats yours? So ok, from what you say below i take it that even with the e1000s you didnt find consistency on different machines. Can you double check at least the kernels are >= 2.6.16? I can tell you this hardware that caused me problems never had flow control working in the earlier kernels. > > Maybe it is read from the eeprom and mine has it off? > > > > Again, note that: It is consuming > 10% (13-15% range) of my bandwidth. > > Granted that is at high speeds with small packets so may not be > > reflective of 96% of the world. But that would be > 50kpps of my > > forwarding capacity being chewed unreasonably. So Auke, did you say > > "performance" was what people mostly bitched about? ;-> > > yes, but that's linked with hardware that doesn't handle flowcontrol events > properly, As i mentioned earlier: This is actually hardware that works with flow control ;-> When it doesnt work - as in the case of the one i found advertising but not respecting flow control the bandwidth being consumed was > 60% ;-> To give you perspective, on average that is > 500Mbps > if you were doing large message TCP transfers over that you'd > probably see even worse performance I bet (retransmits being dropped etc). > I havent tested that, but it does seem unlikely. > Jesse is working on performance stuff, he'll gladly look into it :) > Jesse, if you want to reproduce this talk to me and i will give you a description of how to do it. Make sure you can record flow control packets both in send and receive. > >>> As said earlier, e1000 always honors the EEPROM setting for this, which has > >>> been _on_ by default for all cards (AFAIK, that is). > > > > It has _never ever_ worked on e1000 for as long as i have used e1000. If > > it was intended to work, it must have been fixed in 2.6.16. So it is new > > behavior. > > Turns out that of the e1000 cards I can find around here that are plugged in > actually are 50-50 distributed on/off, so I was wrong about it being on by > default everywhere. > > Looking back through the code I see no changes affecting flow control setup as > early as 2.6.12 ... There are some minor (new) HW changes but nothing that > should have boken fc. > It could be something very basic. Since you have access to a variety of hardware (and variety of kernels i take it), you can go by elimination and find it. cheers, jamal