On Fri, 2019-06-28 at 17:14 +0300, Mika Westerberg wrote: > On Fri, Jun 28, 2019 at 03:33:56PM +0200, Timur Kristóf wrote: > > I have two more questions: > > > > 1. What is the best way to test that the virtual link is indeed > > capable > > of 40 Gbit / sec? So far I've been unable to figure out how to > > measure > > its maximum throughput. > > I don't think there is any good way to test it but the Thunderbolt > gen 3 > link is pretty much always 40 Gb/s (20 Gb/s x 2) from which the > bandwidth is shared dynamically between different tunnels (virtual > links). That's unfortunate, I would have expected there to be some sort of PCIe speed test utility. Now that I gave it a try, I can measure ~20 Gbit/sec when I run Gnome Wayland on this system (which forces the eGPU to send the framebuffer back and forth all the time - for two 4K monitors). But it still doesn't give me 40 Gbit/sec. > > > 2. Why is it that the game can only utilize as much as 2.5 Gbit / > > sec > > when it gets bottlenecked? The same problem is not present on a > > desktop > > computer with a "normal" PCIe port. > > This is outside of my knowledge, sorry. How that game even knows it > can > "utilize" only 2.5 Gbit/s. Does it go over the output of "lspci" as > well? :-) > > The PCIe links itself should to get you the 8 GT/s x 4 and I'm quite > sure the underlying TBT link works fine as well so my guess is that > the > issue lies somewhere else but where, I have no idea. > > Maybe the problem is in the game itself? I had a brief discussion with Marek about this earlier, and he said that this has to do with latency too, not just bandwidth, but he didn't explain any further. _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
