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Last time i looked at intel scatter/gather I got the impression it only works for a very narrow use case, and getting it to perform wasn’t easy. Did I miss something?

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The post says, about SIMT / GPU programming, "This loss results from the DRAM architecture quite directly, the GPU being unable to do much about it – similarly to any other processor."

I would say that for SIMD the situation is basically the same. gather/scatter don't magically make the memory hierarchy a non-issue, but they're no longer adding any unnecessary pain on top.

Barrel threaded machines like GPUs have easier time hiding the latency of bank conflict resolution when gathering/scattering against local memory/cache than a machine running a single instruction thread. So pretty sure they have a fundamental advantage when it comes to the throughput of scatter/gather operations that gets bigger with a larger number of vector lanes

vpgatherdd - I think that for newer CPUs it is faster than many loads + inserts, but if you are going to fault a lot, then it becomes slow.

> The VGATHER instructions are implemented as micro-coded flow. Latency is ~50 cycles.

https://www.intel.com/content/www/us/en/content-details/8141...

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