Subject: Re: Configuring memory parameters for large network-based services
To: Michael Graff <>
From: Jason Thorpe <>
List: tech-kern
Date: 03/22/1999 17:07:00
On Mon, 22 Mar 1999 12:48:21 -0800 
 Jason Thorpe <> wrote:

 >  > That is, what units is this in?  I'm guessing 2048 (cluster size)
 >  > bytes.
 > No, "clusters" in this sense is the historic "page cluster", i.e.
 > VM page size (as opposed to hardware page size :-)  In the NetBSD
 > kernel, CLBYTES == PAGE_SIZE :-)
 > Confusing enough yet? :-)
 > So, on i386, 4k.  On Alpha, 8k.  On SPARC, 8k.  Etc.

BTW, after reexamination of the code, NMBCLUSTERS does in fact mean
"number of mbuf clusters", not "number of VM pages in map".  I have
clarified this in options(4), and fixed the ports which defined it
incorrectly (the PowerPC ports).

        -- Jason R. Thorpe <>