alt Hacker NewsUSB doesn’t provide any DMA (until USB 4) and requires more host cpu resources to meet the same bandwidth. It also has less consistent performance by virtue of the USB protocol itself.
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mianos • 01/17/2025
I am confused by this, I worked on a Linux USB driver that used DMA in 2003.
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at least for Gigabit speeds, the CPU usage is negligible if the device and the driver are communicating through CDC-NCM protocol, but yeah it's a significant hit if you're using CDC-ECM...,