RDNA2+ cards seem to be underutilized, because of dual compute unit design? #186
Description
From my understanding of RDNA2 architecture each RDNA2 (and newer) will report only half of CUs to the OpenCL.
(from the whitepaper)
The new dual compute unit design is the essence of the RDNA architecture and replaces the GCN compute unit as the fundamental computational building block of the GPU. As Figure 2 illustrates, the dual compute unit still comprises four SIMDs that operate independently. However, this dual compute unit was specifically designed for wave32 mode; the RDNA SIMDs include 32 ALUs, twice as wide as the vector ALUS in the prior generation, boosting performance by executing a wavefront up to 2X faster. The new SIMDs were built for mixedprecision operation and efficiently compute with a variety of datatypes to enable scientific computing and machine learning. Figure 3 below illustrates how the new dual compute unit exploits instruction-level parallelism within a simple example shader to execute on a SIMD with half the latency in wave32 mode and a 44% reduction in latency for wave64 mode compared to the previous generation GCN SIMD.
The result is that it seems that the GPUs are underutilized.