Advanced Computer Architecture Chapter 7.34
Larger MPs
Separate Memory per Processor
Local or Remote access via memory
controller
1 Cache Coherency solution: non-cached pages
Alternative: directory per cache that tracks state of every block
in every cache
Which caches have a copies of block, dirty
vs. clean, ...
Info per memory block vs. per cache
block?
PLUS: In memory => simpler protocol
(centralized/one location)
MINUS: In memory => directory is ƒ(memory
size) vs. ƒ(cache size)
Prevent directory as bottleneck? distribute directory entries with memory, each keeping track of which Procs have copies of their blocks