dman <[EMAIL PROTECTED]> writes: > On Tue, Dec 11, 2001 at 01:17:30PM -0500, David Teague wrote: > | > | > | If you put more RAM in a computer system than the caching system > | will suppport, the system will run more slowly than it would with > | less RAM. IF I understand correctly, the amount of RAM depends on > | the amount of tag RAM. > | > | I have 512 MB on my Abit MoBo with a 1GHz Athlon. > | > | How do I determine how much RAM the L1 cache in a 1GHz Athlon will > | support? > > According to > http://www.amd.com/us-en/Processors/ProductInformation/ > 0,,30_118_756_759%5E1151,00.html > > (all on one line) > > Cache Architecture: The AMD Athlon processor boasts a 384K total > full-speed on-chip system cache including 128K L1 cache--four > times that of Intel's Pentium III processor--and 256K on-chip > full-speed L2 cache. > > > There is no limit on the amount of system RAM based on processor > cache. Certainly when you have many cache misses, you lose > performance, but the whole purpose of cache is to try and guess which > memory you will need next (through some hueristic algorithms) so that > you have a cache hit and don't have to go all the way out to that very > (relatively!) slow memory.
Umm, not quite. There can be a limit on the amount of RAM that can be cached based on the processor, but more common is a limit based on the chipset, which I believe is what David was basing his question on. Namely the 430(FX|VX|TX|HX) chipsets were, generally, limited to caching 64MB of RAM. Even given the chipset you can't automatically say what amount of RAM it could cache. A quick google search pulled up the following that may be of interest: http://www.makeitsimple.com/articles/ramguide/ramguidep6.htm http://www.stud.fernuni-hagen.de/q3998142/pcchips/howto/cache.html http://www.tomshardware.com/site/faq.html Of course, David was asking about an Athlon system. As far as I know neither the latest PIV or the Athlon boards/CPUs have a limit on the amount of RAM that can be cached. At least to the limit of RAM the particular board supports. Gary
