[pups] Progress on 2.11BSD kernel

David Evans dfevans at bbcr.uwaterloo.ca
Thu Mar 20 09:15:16 AEST 2003

On Wed, Mar 19, 2003 at 03:08:46PM -0800, Steven M. Schultz wrote:
> >   OK.  From what I recall (that turned-off machine again...) the entire
> > discussion on tuning MAXUSERS and friends is based on allocation of UMRs.
> > Might be a good idea to slip in a note about what to do when you don't have
> 	It is less a matter of MAXUSERS than it is of NBUF.   NBUF sets
> 	the number of disc cache buffers.

  Yeah, sorry, it was NBUF that I was thinking of.  It's been aboutn a month
since I've had a chance to fiddle with my /73.

> 	The other constraint, even for Qbus systems, is the D space requirement.
> 	The 1KB portion of the disc buffer is "external" to the kernel (is 
> 	mapped in/out as needed) but there is a header structure which is
> 	part of the kernel's permanent address space.  Each buffer header is
> 	24 bytes so even without UMRs around it's not feasible to have a 200KB
> 	cache because that'd use 4800 bytes of kernel D space (which is always
> 	on the edge of being overflowed it seems).

  Cool, thanks.

David Evans          (NeXTMail/MIME OK)             dfevans at bbcr.uwaterloo.ca
Ph.D. Candidate, Computer/Synth Junkie     http://bbcr.uwaterloo.ca/~dfevans/
University of Waterloo         "Default is the value selected by the composer
Ontario, Canada           overridden by your command." - Roland TR-707 Manual

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