From owner-freebsd-net@FreeBSD.ORG Fri Sep 5 23:21:18 2014 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 57425E5; Fri, 5 Sep 2014 23:21:18 +0000 (UTC) Received: from esa-annu.net.uoguelph.ca (esa-annu.mail.uoguelph.ca [131.104.91.36]) by mx1.freebsd.org (Postfix) with ESMTP id A93281DD9; Fri, 5 Sep 2014 23:21:16 +0000 (UTC) X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AqwEALJEClSDaFve/2dsb2JhbABag2BXBIJ4xhsKhnlTAYEad4QEAQEEAQEBICsdAwsbEgYCAg0ZAikBCRgOBggHBAEcBIghDal3lTkBF4EsjVABAQEaNAeCeYFTBZVug3uEX5NKg30hLweBCDmBBwEBAQ X-IronPort-AV: E=Sophos;i="5.04,476,1406606400"; d="scan'208";a="153076390" Received: from muskoka.cs.uoguelph.ca (HELO zcs3.mail.uoguelph.ca) ([131.104.91.222]) by esa-annu.net.uoguelph.ca with ESMTP; 05 Sep 2014 19:21:15 -0400 Received: from zcs3.mail.uoguelph.ca (localhost.localdomain [127.0.0.1]) by zcs3.mail.uoguelph.ca (Postfix) with ESMTP id 8C263B404B; Fri, 5 Sep 2014 19:21:15 -0400 (EDT) Date: Fri, 5 Sep 2014 19:21:15 -0400 (EDT) From: Rick Macklem To: Hans Petter Selasky Message-ID: <1527367342.33029385.1409959275542.JavaMail.root@uoguelph.ca> In-Reply-To: <540A3C91.406@selasky.org> Subject: Re: [RFC] Patch to improve TSO limitation formula in general MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Originating-IP: [172.17.91.203] X-Mailer: Zimbra 7.2.6_GA_2926 (ZimbraWebClient - FF3.0 (Win)/7.2.6_GA_2926) Cc: freebsd-net@freebsd.org, Eric Joyner , FreeBSD Current , Scott Long , Jack F Vogel X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 05 Sep 2014 23:21:18 -0000 Hans Petter Selasky wrote: > On 09/06/14 00:09, Rick Macklem wrote: > > Hans Petter Selesky wrote: > >> On 09/05/14 23:19, Eric Joyner wrote: > >>> There are some concerns if we use this with devices that ixl > >>> supports: > >>> > >>> - The maximum fragment size is 16KB-1, which isn't a power of 2. > >>> > >> > >> Hi Eric, > >> > >> Multiplying by powers of two are more fast, than non-powers of > >> two. > >> So > >> in this case you would have to use 8KB as a maximum. > >> > > Well, I'm no architecture expert, but I really doubt the CPU delay > > of a > > non-power of 2 multiply/divide is significant related to doing > > smaller > > TSO segments. Long ago (as in 1970s) I did work on machines where > > shifts > > for power of 2 multiply/divide was preferable, but these days I > > doubt it > > is going to matter?? > > > > Hi, > > You also need to patch LAGG and VLAN drivers? > Yep. I already ran into the fact that these drivers didn't pass if_hw_tsomax up and patched them for that recently. The same will be necessary for if_hw_tsomaxseg if/when it goes into head. As I said, this patch is currently completely untested and, even once I get it tested/working, there will need to be a discussion on freebsd-net@ w.r.t. whether it is appropriate for head. I will take a look at your patch around Monday. Btw, when setting if_hw_tsomax as I suggested in the first post, you will still end up doing a lot of m_defrag() calls for NFS RPC messages, but at least they will get through. rick > --HPS > > _______________________________________________ > freebsd-net@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-net > To unsubscribe, send any mail to > "freebsd-net-unsubscribe@freebsd.org" >