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The thread specifically says that they bet on fast transfer on and off of the gpu becoming common, and then the exact opposite of that happened. When you care a
by plorkyeran 5y ago
The thread specifically says that they bet on fast transfer on and off of the gpu becoming common, and then the exact opposite of that happened. When you care about a performance characteristic that no one else cares about, you're going to get very weird performance results and it's not a given that a gpu better for normal workloads will be better for you.
- terafo 5y agoTransfer on and off the GPU is limited mostly by PCIe and the latest Mac Pro that performs almost like M1 Max in rasterization has only PCIe3.0, while PCIe gen 4 with double the bandwidth is available on many PCs. If you look closely at the benchmarks performance doesn't correlate with PCIe bandwidth, and even if it did, it doesn't explain nearly 3x difference between 3090 and W6900X.
- MobiusHorizons 5y agoIIUC on the M1, transfer happens using unified memory. This should mean the bandwidth is not limited by pcie but rather by the memory bandwidth, which was quite high if I remember correctly. I
- terafo 5y agoMemory bandwidth in w6900x is roughly 500gb/s. In 3090 it's more than 900gb/s. Yet, 3090 performs like 5500M(which is laughable). In M1 Max bandwidth is 400gb/s(but there is 200gb/s version). I'm comparing only raster performance which should be heavily GPU dependent.
- MobiusHorizons 5y agoThe difference is that with the w6900x, the memory bandwidth is not used to transfer data between the dGPU and main memory. That happens over PCIe instead.