Increasing buffer cache

[orjan]

I have some questions re. an ICL Clan 6 running Tahoe/SysVR2 (an OEM of
some CCI machine)
I want to increase the buffer cache by defining 'buffers' in the
config file (ie nbuf in /usr/src/uts/machine/cf/space.c).
Increasing buffers to much gives a messages when booting
saying 'system page table to small' or something similar and a
non-working system (process tables etc messed up etc).
The system administrator manual says (in 'Configuring the system/run time
calculations') that
"the amount of physical memory allocated to the buffer cache is
constrained by the size of the system page tables, among other things".
                                                   ^^^^^^^^^^^^^^^^^^
My questions are:

Sysptsize is defined in .../machine/cf/space.c and SYSPTSIZE in 
.../machine/ml/sysmap.s.
How much should/can I increase them to get like a 5 Mb buffer cache
on a 16 Mb system. At present I only get up to 3.2 Mb without running
into the system page table limit.

What are the "other things"  mentioned ?

E-mail any answers please - I will summarize if there is any interest.
Any help will be appreciated!

   . .
	Orjan

-- 
     Orjan Petersson           |  orjan at im.se
     Industrimatematik Data AB |  orjan at cs.chalmers.se
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