3 ms·
64-bit ARM NEON (SIMD instruction set) is much more efficient vs 32-bit. And not just NEON, there are more registers as well, deeper pipeline, etc.
by yalok 7y ago
64-bit ARM NEON (SIMD instruction set) is much more efficient vs 32-bit. And not just NEON, there are more registers as well, deeper pipeline, etc.
- xeeeeeeeeeeenu 7y agoAlso, 32-bit ARMs often (but not always) don't have hardware integer division.
- pm215 7y agoInteger division is mandatory from v7VE on upwards (so roughly Cortex-A9, A15 and later), and it's definitely in the 32-bit support of any 64-bit capable core. If Raspbian is compiling its packages for the lowest common denominator arm v6 cpu some Pis have, then you'd get some slowdown from division being an out-of-line call (to library code that can use the hw insn), but you'd see that part of the speedup just from building for 32-bit but optimised for newer cores than v6, I think.
- xeeeeeeeeeeenu 7y ago>If Raspbian is compiling its packages for the lowest common denominator arm v6 cpu some Pis have It is definitely the case, the official Raspbian images support Raspberry Pi 1.
- my123 7y agoCortex-A9 does not have hardware division. Cortex-A7 and Cortex-A15 onwards do.
- pm215 7y agoYes, you're right, I misremembered. (It came in with CPUs with the virtualization extension, so not A9.)