🚀 go-pugleaf

Hi folks.

>chuckf@charm.net (Chuck Frain) writes:
some snipping...
>>Just a little note here....256k cache is worth getting up to 32 megs of 
>>ram. After 32 megs go to 512k. If you go to 512k with less than 32megs 
>>of RAM it will actually slow the system down. At my part itme job we 
>>did some benchmarking with this and found it to be true with every MB 
>>that we tried. 
That may very well be true but I would like to know what benchmark you
were running. In general the larger cache gives a better hit rate and 
thus higher performance no matter how much main memory you have and what
OS you are running, measured with normal bench marks. If not, the
motherboard maybe flushes the cache too often and it really takes longer
to flush a larger cache. A good design never flushes the cache except at
boot time. Another reason is the fact that a 512k asyncrounus cache often
is configured as dual bank and sometimes need an extra clock either 
between even and odd addresses (poor design) or between the banks.
The 32 Mb limit is interesting. If the cache is a direct mapped 256k and
has 7 tag bits it's able to cover 32 Mb. Adding more memory in this
case will actually slow the system down depending on OS! The memory above
32Mb will not be cached.

Jan