4 ms·
The CPU does know the physical address, because the MMU is part of the CPU; so you can have a physically indexed cache if you want. The problem is just that you
by pm215 10y ago
The CPU does know the physical address, because the MMU is part of the CPU; so you can have a physically indexed cache if you want. The problem is just that you can't do the cache lookup in parallel with the MMU physical-to-virtual lookup, so it's slower than if you used a virtually-indexed cache.
- bogomipz 10y agoSure, I didn't articulate my comment very well. I meant to say that the L1-3 caches operate on virtual addresses because they don't know the physical address but the MMU does since all memory access must transit through the MMU.