Date: Wed, 26 Apr 2000 10:49:20 -0400 (EDT) From: Andrew Gallatin <gallatin@cs.duke.edu> To: Dennis <dennis@etinc.com> Cc: hackers@freebsd.org Subject: Re: Large mbufs? Message-ID: <14598.65443.725745.6119@grasshopper.cs.duke.edu> In-Reply-To: <200004261359.JAA16855@etinc.com> References: <200004261359.JAA16855@etinc.com>
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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
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