[Info-vax] RealWorldTech on Poulson

[JF Mezei]

re: chache coherency and virtual machines.

Say you have a 32 core system running 16 instances of some OS versus the
same system running one instance of the OS.

>From a cache performance/coherency point of view, does this make a
difference ?


With  a single instance, you'd have 32 cores accessing the same memory.
So obviously, the scalability issue mentioned in this thread will matter.

But in the case of 16 instances of 2 cores each, wouldn't the cache
become effectively split 16 ways since no OS instance could touch
another's memory ? If each portion of the cache that is being used by
one OS instance is only accessed by 2 CPUs then scalability wouldn't be
an issue ? or would it ?

I realise that the cache manager would still see the big picture and not
realise that memory has been split 16 ways.