How do I disable cache?

[E. Robert Tisdale]

I installed Yellow Dog Linux 2.3 on an Apple PowerBook G3
(400MHz/1MB Cache/64MB/6GM HD/8MB Video/DVD).
Now I need to run some performance benchmarks with the cache disabled.
Can somebody point me to detailed instructions
that will permit to turn off the cache while I run these benchmarks?

Thanks in advance.