> I had to move SSD cards around so they'd use separate PCIe root complexes to avoid a PCIe <-> CPU data transfer bottleneck I am doing similar things. Have yo

> I had to move SSD cards around so they'd use separate PCIe root complexes to avoid a PCIe <-> CPU data transfer bottleneck I am doing similar things. Have you considered looking at how to control by software the PCI lanes assignment? Intel HSIO seems to be software configurable - except that usually, it's all done just by the bios. But as PCI specs allow for both device-side and host-side negotiations, it should be doable without "moving SSDs around" > The throughput differs depending on which specific CPU cores happen to run the processes doing I/Os against different SSDs. That strikes me as odd. I would check the detail of the PCI lanes and their routing. You could have something funky going on. My first guess would be that it's slow on one core because it's also handling something else, by design or by accident. There're some bad hardware designs out there. But thanks to stuff like HSIO, it should now be possible to fix the worst ones by software (how else would the bios do it otherwise!) just like in the old days of isapnptools!