From owner-freebsd-net@FreeBSD.ORG Wed Jan 29 19:23:00 2014 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id D119EA18 for ; Wed, 29 Jan 2014 19:23:00 +0000 (UTC) Received: from h2.funkthat.com (gate2.funkthat.com [208.87.223.18]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id ABFEF1D0A for ; Wed, 29 Jan 2014 19:23:00 +0000 (UTC) Received: from h2.funkthat.com (localhost [127.0.0.1]) by h2.funkthat.com (8.14.3/8.14.3) with ESMTP id s0TJLcuF002771 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Wed, 29 Jan 2014 11:21:38 -0800 (PST) (envelope-from jmg@h2.funkthat.com) Received: (from jmg@localhost) by h2.funkthat.com (8.14.3/8.14.3/Submit) id s0TJLbe6002770; Wed, 29 Jan 2014 11:21:37 -0800 (PST) (envelope-from jmg) Date: Wed, 29 Jan 2014 11:21:37 -0800 From: John-Mark Gurney To: Garrett Wollman Subject: Re: Big physically contiguous mbuf clusters Message-ID: <20140129192137.GF93141@funkthat.com> Mail-Followup-To: Garrett Wollman , freebsd-net@freebsd.org References: <21225.20047.947384.390241@khavrinen.csail.mit.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <21225.20047.947384.390241@khavrinen.csail.mit.edu> User-Agent: Mutt/1.4.2.3i X-Operating-System: FreeBSD 7.2-RELEASE i386 X-PGP-Fingerprint: 54BA 873B 6515 3F10 9E88 9322 9CB1 8F74 6D3F A396 X-Files: The truth is out there X-URL: http://resnet.uoregon.edu/~gurney_j/ X-Resume: http://resnet.uoregon.edu/~gurney_j/resume.html X-TipJar: bitcoin:13Qmb6AeTgQecazTWph4XasEsP7nGRbAPE X-to-the-FBI-CIA-and-NSA: HI! HOW YA DOIN? can i haz chizburger? X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.2.2 (h2.funkthat.com [127.0.0.1]); Wed, 29 Jan 2014 11:21:38 -0800 (PST) Cc: freebsd-net@freebsd.org X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.17 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 29 Jan 2014 19:23:00 -0000 Garrett Wollman wrote this message on Wed, Jan 29, 2014 at 13:54 -0500: > Resolved: that mbuf clusters longer than one page ought not be > supported. There is too much physical-memory fragmentation for them > to be of use on a moderately active server. 9k mbufs are especially > bad, since in the fragmented case they waste 3k per allocation. I agree, but I am split on removing the code as there are still very broken controllers that may require them, though in those cases, it might be helpful to have a tunable that lets you set how many jumbo frames are allocated at boot, and these pages are never released back to the system... We definately need to fix all the drivers that use MJUM9BYTES which apparently are quite a few: http://fxr.watson.org/fxr/ident?im=excerpts;i=MJUM9BYTES -- John-Mark Gurney Voice: +1 415 225 5579 "All that I will do, has been done, All that I have, has not."