Device to host bandwidth limiting factor
I would like to know if anyone could explain what is the limiting factor that leads to a device to host bandwidth of 2.6GiB/s as benchmark in the above link?
Thunderbolt 3 with PCIe 3 x4 is 32Gib/s so we should in theory be able to achieve 4GiB/s.
Also, on the same page, the GTX 1070 shows 6GiB/s of memory read, how is this possible?
Thanks for any insights.
There is no clear explanation. Thunderbolt 3 is limited to 22 Gbps (2750 MB/s) because reasons...
Even if you try to raid both Thunderbolt ports of a Thunderbolt 3 controller, you only get about 23 Gbps.
When USB4 arrives, we'll see if the same is true for that. At least with USB4, the spec is open and available. In the USB4 spec, it mentions a tradeoff between latency and throughput. Maybe this also applies to Thunderbolt 3 (it refers to PCIe tunnelling which Thunderbolt supports, and also USB4 tunnelling which of course is new to USB4).
DisplayPort tunnelling has different behaviour because a certain bandwidth is required (depends on resolution and color depth).