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GPUs aren't cache-coherent yet. That said, they have fantastic atomic ops performance relative to CPUs. I'd guess that the lack of performance benefit so far
by varelse 11y ago
GPUs aren't cache-coherent yet. That said, they have fantastic atomic ops performance relative to CPUs. I'd guess that the lack of performance benefit so far is because it's possible to write many algorithms with the assumption that there is no cache coherency.
- robmccoll 11y agoTheir atomic operations used to be extremely costly from a utilization perspective. They would shut down all other threads in a warp while the thread performing the atomic ran alone. Is that still the case?
- varelse 11y agoFixed as of Maxwell to the best of my knowledge. But even then, I found them more efficient for reduction operations in global memory than any other method (using fixed-point math for places where a deterministic sum was required).