[zamadatix]

> PCIe P2P transfers go through the CPU

PCIe P2P transfers can go direct through a downstream PCIe switch such as found on chipsets without having to bump back up through the CPU.

[namibj]

And even with e.g. AMD Matisse, aka Desktop Ryzen Zen3 on AM4, it turns around in the PCIe root complex instead of consuming infinity fabric bandwidth.