From owner-freebsd-hackers Wed Apr 26 7:49:26 2000 Delivered-To: freebsd-hackers@freebsd.org Received: from duke.cs.duke.edu (duke.cs.duke.edu [152.3.140.1]) by hub.freebsd.org (Postfix) with ESMTP id DE7F837BDA7 for ; Wed, 26 Apr 2000 07:49:22 -0700 (PDT) (envelope-from gallatin@cs.duke.edu) Received: from grasshopper.cs.duke.edu (grasshopper.cs.duke.edu [152.3.145.30]) by duke.cs.duke.edu (8.9.3/8.9.3) with ESMTP id KAA26767; Wed, 26 Apr 2000 10:49:21 -0400 (EDT) Received: (from gallatin@localhost) by grasshopper.cs.duke.edu (8.9.3/8.9.1) id KAA29394; Wed, 26 Apr 2000 10:49:20 -0400 (EDT) (envelope-from gallatin@cs.duke.edu) From: Andrew Gallatin MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Date: Wed, 26 Apr 2000 10:49:20 -0400 (EDT) To: Dennis Cc: hackers@freebsd.org Subject: Re: Large mbufs? In-Reply-To: <200004261359.JAA16855@etinc.com> References: <200004261359.JAA16855@etinc.com> X-Mailer: VM 6.43 under 20.4 "Emerald" XEmacs Lucid Message-ID: <14598.65443.725745.6119@grasshopper.cs.duke.edu> Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG Dennis writes: > Is there support for large mbufs in v4.0? (that is, allocations of any size?) > There are 2 ways to use large mbufs: o options MCLSHIFT=XXXX in your kernel config file. Where XXX is 1 << XXX bytes. Eg, MCLSHIFT=12 is 4K mbuf clusters, MCLSHIFT=13 is 8k clusters, etc. config will complain, but it will work. There are several drawbacks to this method. The most glaring is that you'll probably be wasting an awfully large amount of space. o allocate & manage them yourself, using m_ext mbufs, within the subsystem you feel needs them. See the Tigon (sys/pci/if_ti.c) driver's management of jumbo frame receive buffers for an example of how this is done. Hope this helps, Drew ------------------------------------------------------------------------------ Andrew Gallatin, Sr Systems Programmer http://www.cs.duke.edu/~gallatin Duke University Email: gallatin@cs.duke.edu Department of Computer Science Phone: (919) 660-6590 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message