ESDI caching disk controllers: Reprise

[Richard Foulk]

>> With a 768K cache memory on one card I routinely get 32% cache hits
>> and with 4Mb on the one in ssbn I get 48-52% cache hits.
>
>I have never understood this.  If a caching disk controller with 4Mb gives
>you a high hit rate, why not put the 4Mb of RAM into your CPU, and
>let UNIX use it as a cache?  The hit rate should be the same.
>The win is that the OS should be able to divide the RAM between disk
>cache and process space (I assume UNIX isn't brain-dead in this regard?).
>Then you have the best of both worlds.

I have vague recollections of several different sets of research into
the disk cache versus more main-memory question using Unix.  Adding to
main memory almost always won out as I recall -- at least with proper
tuning.

The disk cache is certainly a win with MESS-DOS since it doesn't have
any idea what to do with more memory.  I think that's where these
boards are coming from.

-- 
Richard Foulk		richard at pegasus.com