> > > > Like I said the device really is limited to 2.5 GT/s even > > > > though it > > > > should be able to do 8 GT/s. > > > > > > There is Thunderbolt link between the host router (your host > > > system) > > > and > > > the eGPU box. That link is not limited to 2.5 GT/s so even if the > > > slot > > > claims it is PCI gen1 the actual bandwidth can be much higher > > > because > > > of > > > the virtual link. > > > > Not sure I understand correctly, are you saying that TB3 can do 40 > > Gbit/sec even though the kernel thinks it can only do 8 Gbit / sec? > > > > I haven't found a good way to measure the maximum PCIe throughput > > between the CPU and GPU, but I did take a look at AMD's sysfs > > interface > > at /sys/class/drm/card1/device/pcie_bw which while running the > > bottlenecked game. The highest throughput I saw there was only 2.43 > > Gbit /sec. > > > > One more thought. I've also looked at > > /sys/class/drm/card1/device/pp_dpm_pcie - which tells me that > > amdgpu > > thinks it is running on a 2.5GT/s x8 link (as opposed to the > > expected 8 > > GT/s x4). Can this be a problem? > > We limit the speed of the link the the driver to the max speed of any > upstream links. So if there are any links upstream limited to 2.5 > GT/s, it doesn't make sense to clock the local link up to faster > speeds. > > Alex Hi Alex, I have two concerns about it: 1. Why does amdgpu think that the link has 8 lanes, when it only has 4? 2. As far as I understood what Mika said, there isn't really a 2.5 GT/s limitation there, since the virtual link should be running at 40 Gb/s regardless of the reported speed of that device. Would it be possible to run the AMD GPU at 8 GT/s in this case? Best regards, Tim _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
