Hacker News Reader

I was not very specific. What I meant to get at was that if your bottleneck is memory, then optimizing for instructions is not going to help. is_sort is an example algorithm that's far more dependent on memory than it is on instruction throughput.

If your bottleneck isn't memory, then yeah, SIMD is a real boon.

View on HN

It’s not all about compute. SIMD instructions allow you to load more bits per instruction cycle. When you are doing sequential access on a modern processor, this can make a huge difference. It allows you to use the memory bandwidth to its full capacity.

It's rare to have a meaningful algorithm where memory is the absolute only bottleneck. Not much else aside from memcpy and even that can see a benefit from SIMD tuning on many systems.

Especially since high performance software is glad to have even a 1% boost in speed.

Reply on news.ycombinator.com