16-bit memory, caches, and UNIX V/386

[David F. Carlson]

In article <8746 at saturn.ucsc.edu>, laurie at ucscb.UCSC.EDU (60648000) writes:
> 
> I was running a AST premium 386/20 with 2.6mb of 32 bit memory. I then added 
> a 2mb 16 bit 100 ns memory card and when running graphics programs that 
> malloc'ed HUGE data structures (1-2 mb), my box ran about 40-60 % slower. 
> I was really suprised at the diff.
> 
> Ken Chapin

A wish list item of mine is to be able to dedicate certain memory ranges
for the el-cheapo 16 bit memory to be used for LARGE, inexpensive buffer
cache memory.  Ken is quite correct that the large number of WS kill kernel
and user space performance but having 4-8 meg of buffer cache would be much
faster than 350K in cache.  (Besides which, buffer writes from disk or user
space take a performance hit to 32bit cached memory because of write-through
strategies anyway.  (Write-back will have a cache write that will be line
buffered;  not as bad but still not great.)


-- 
David F. Carlson, Micropen, Inc.
micropen!dave at ee.rochester.edu

"The faster I go, the behinder I get." --Lewis Carroll