On Fri, Apr 3, 2009 at 2:54 PM, Matthew W. Ross <[email protected]> wrote: > Isn't PAE a non-trivial memory performance hit? Or perhaps it used to be > non-trivial, > but newer memory technologies are fast enough to make it trivial today?
I don't know the details, but I believe so. PAE has two major effects that I'm aware of: * The physical address word increases from 32 bits to 36 bits. * A third level of page table indirection is introduced, to allow the MMU to map the additional memory with minimal architectural change. I can't see how additional page table indirection could *not* slow things down. And it wouldn't surprise me to find that the large physical address word means slower operations need to be used for memory management. I don't know much about the memory architecture of long mode (64-bit), but it may be that the page table layout is less cumbersome, being designed for larger memories from day one. There may be a performance gain from running Win64 for that reason, even if one only has a smaller memory system and Win32 software. Anyone have benchmarks? (Obviously a Win64 system will be a win if one has larger memories, but I'm curious if it would pay off on, e.g., a 1 GB RAM system.) -- Ben ~ Finally, powerful endpoint security that ISN'T a resource hog! ~ ~ <http://www.sunbeltsoftware.com/Business/VIPRE-Enterprise/> ~
