3 ms·

It absolutely can! On ARM you can just enter a block entree in a non-leaf page table to allocate an entire block of physically contiguous memory in a single TLB

It absolutely can! On ARM you can just enter a block entree in a non-leaf page table to allocate an entire block of physically contiguous memory in a single TLB entry. From the ARM docs [1], any CPU supporting 16K translation granules will support 32MB L2 blocks. I suspect, however, that apple can't really allocate that many (if any at all) 32MB regions of memory at runtime due to fragmentation unless they've substantially changed their contiguous memory allocator since I last looked. [1] https://developer.arm.com/documentation/den0024/a/The-Memory-Management-Unit/Translation-tables-in-ARMv8-A/Effect-of-granule-sizes-on-translation-tables https://developer.arm.com/documentation/den0024/a/The-Memory...

scottlamb 5y ago
Interesting, thanks! > I suspect, however, that apple can't really allocate that many (if any at all) 32MB regions of memory at runtime due to fragmentation unless they've substantially changed their contiguous memory allocator since I last looked. That's unfortunate but at least is something they could fix in upcoming software versions. Some folks have put a lot of effort into huge pages on Linux, and it's still ongoing. [1] Not too surprising that macOS could have some room for improvement... [1] https://lwn.net/Articles/887753/ https://lwn.net/Articles/887753/