3 ms·
> A 32 entry iTLB helps cache virtual to physical address translations on the instruction side. Why are TLBs so small? Are they super expensive or what? With 3
by codedokode 3y ago
> A 32 entry iTLB helps cache virtual to physical address translations on the instruction side.
Why are TLBs so small? Are they super expensive or what? With 32 entries TLB it can cover only 1 Mb of RAM if using legacy 4k pages.
- johndoe0815 3y agoYes, TLBs are pretty expensive (in area and power) since they are associative memories. The virtual (non-offset) part of an address to be translated is compared to all TLB entries simultaneously to keep latencies down since the TLB is on the critical path from CPU to memory. Accordingly, you need one comparator (lots of XOR gates in a simple implementation) per TLB entry.