> > Thanks Marek, I didn't know about that option. > > Tried it, here is the output: https://pastebin.com/raw/9SAAbbAA > > > > I'm not quite sure how to interpret the numbers, they are > > inconsistent > > with the results from both pcie_bw and amdgpu.benchmark, for > > example > > GTT->VRAM at a 128 KB is around 1400 MB/s (I assume that is > > megabytes / > > sec, right?). > > Based on the SDMA results, you have 2.4 GB/s. For 128KB, it's 2.2 > GB/s for GTT->VRAM copies. > In the meantime I had a chat with Michel on IRC and he suggested that maybe amdgpu.benchmark=3 gives lower results because it uses a less than optimal way to do the benchmark. Looking at the results from the mesa benchmark a bit more closely, I see that the SDMA can do: VRAM->GTT: 3087 MB/s = 24 Gbit/sec GTT->VRAM: 2433 MB/s = 19 Gbit/sec So on Polaris at least, the SDMA is the fastest, and the other transfer methods can't match it. I also did the same test on Navi, where it's different: all other transfer methods are much closer to the SDMA, but the max speed is still around 20-24 Gbit / sec. I still have a few questions: 1. Why is the GTT->VRAM copy so much slower than the VRAM->GTT copy? 2. Why is the bus limited to 24 Gbit/sec? I would expect the Thunderbolt port to give me at least 32 Gbit/sec for PCIe traffic. Mika, do you maybe have an explanation? Thanks & best regards, Tim _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
