Was curious if anybody has any expected performance numbers for the AMD DMA engine "ptdma"? I'm doing some testing utilizing the "ntb_netdev" module for TCP/IP communication between servers via NTB (Non-Transparent Bridge) using "iperf". I find that on Intel based boxes, utilizing IOAT DMA, I can get approximately 19-20 Gb/s for a simple untuned single iperf instance. However, when running on AMD based boxes (Milan CPUs), and running the latest ptdma driver from the Linux tree, I can only achieve about 2-3 Gb/s. I'm thinking there must be some driver knob that I need to tweek or something. Any help is greatly appreciated. Thanks, Eric
