3 ms·
The NEON coprocessor runs at the same CPU clock, but 20 cycles behind the main CPU. It has its own instruction queue, and as long as the queue isn't full the ma
by 0xfaded 9y ago
The NEON coprocessor runs at the same CPU clock, but 20 cycles behind the main CPU. It has its own instruction queue, and as long as the queue isn't full the main CPU will simply forward instructions to it. If you want to read from the wide registers though, you need to wait the 20 cycles for the coprocessor to catch up.
- pm215 9y agoA quick google suggests this was true for the Cortex-A8 (released in 2005, over a decade ago), but is unlikely to be true for any implementation since, and I would definitely not expect it to be true for a modern 64-bit implementation like the one the article author tested.
- 0xfaded 9y agoThanks for the reply. After much sifting I finally found modern numbers. Gen -> NEON 6 cycles NEON -> Gen 8 cycles So yes, definitely much closer. http://infocenter.arm.com/help/topic/com.arm.doc.uan0015b/Cortex_A57_Software_Optimization_Guide_external.pdf http://infocenter.arm.com/help/topic/com.arm.doc.uan0015b/Co...