Re: genet0 speeds under NetBSD/aarch64 on Rpi4 8 GB using UEFI/ACPI v1.17 firmware

[Jared McNeill <jmcneill%invisible.ca@localhost>]

On Thu, 23 Jul 2020, Paul Mather wrote:

> Thanks for the tips.  I was hoping I would be able to achieve GbE max speeds without any special tuning.  That is what seemed to happen under Raspberry Pi OS.  As someone observed elsewhere in this thread, it's likely the driver in Raspberry Pi OS is implementing hardware offloading and other things that improve throughput.

Hi Paul --

Author of the driver here. A few things about the driver that could 
explain the performance differences you are seeing:

 - No support for polled operation, so we have to deal with the overhead
   of an IRQ per packet.
 - The hardware supports multiple TX and RX queues, but the driver
   currently only uses one for each.
 - NET_MPSAFE option is disabled by default in the kernel, so we can't
   take advantage of multiple CPUs. Even with this option on, the single
   queue limitation above will be a bottleneck.
 - As others have mentioned already in this thread, no support for
   checksum offload.

Take care,
Jared