From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marc Aurele La France Subject: Re: RFC: MTU for serving NFS on Infiniband Date: Thu, 26 Aug 2010 08:43:42 -0600 (Mountain Daylight Time) Message-ID: References: <20100823080543.319143e3@nehalam> <1282672647.2302.15.camel@achroite.uk.solarflarecom.com> <1282688441.22839.34.camel@localhost> <20100824153920.63360072@s6510> <1282823827.2476.663.camel@edumazet-laptop> Mime-Version: 1.0 Content-Type: MULTIPART/MIXED; BOUNDARY="633328-19643-1282833823=:2008" Cc: Stephen Hemminger , Ben Hutchings , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, "David S. Miller" , Alexey Kuznetsov , "Pekka Savola (ipv6)" , James Morris , Hideaki YOSHIFUJI , Patrick McHardy To: Eric Dumazet Return-path: Received: from smtp.srv.ualberta.ca ([129.128.5.19]:59663 "EHLO mail9.srv.ualberta.ca" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753918Ab0HZOov (ORCPT ); Thu, 26 Aug 2010 10:44:51 -0400 In-Reply-To: <1282823827.2476.663.camel@edumazet-laptop> Sender: netdev-owner@vger.kernel.org List-ID: This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --633328-19643-1282833823=:2008 Content-Type: TEXT/PLAIN; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8BIT On Thu, 26 Aug 2010, Eric Dumazet wrote: > Le jeudi 26 août 2010 à 05:40 -0600, Marc Aurele La France a écrit : >> Steady now. There's no need to YELL nor be arrogant. You and I both know >> there's a place for NFS over UDP. That's not changing any time soon. While >> I'm aware of the issue you brought up, it is separate from the one at hand in >> this discussion. >> I do want to thank you, however, for reminding me of TCP. It's something >> 20/20 hindsight says I should have checked out before starting this thread. >> Logistically, it'll be a few days before I can do so though. If that allows >> me to increase the MTU all the way up to 65520, then this UDP thing will >> likely remain unresolved. > Unfortunately, your infiniband device lacks NETIF_F_SG support. Oh, the device itself probably has something similar, but ipoib (IP-over-Infiniband) doesn't export that capability. > MTU a bit larger than PAGE_SIZE-overhead will need high order > allocations ? Right. And a 65520 MTU allocates sk_buff's with 128K contiguous payloads. Marc. +----------------------------------+----------------------------------+ | Marc Aurele La France | work: 1-780-492-9310 | | Academic Information and | fax: 1-780-492-1729 | | Communications Technologies | email: tsi@ualberta.ca | | 352 General Services Building +----------------------------------+ | University of Alberta | | | Edmonton, Alberta | Standard disclaimers apply | | T6G 2H1 | | | CANADA | | +----------------------------------+----------------------------------+ --633328-19643-1282833823=:2008--