On 15.03.18 23:30, John Fastabend wrote:
I have reproduced it using two USB network cards connected to each other. The
test tool sends UDP packets containing a counter and listens on the other
interface, it is available at
https://github.com/jakob-tsd/pfifo_stress/blob/master/pfifo_stress.py
Great thanks, can you also run this with taskset to bind to
a single CPU,
# taskset 0x1 ./pifof_stress.py
And let me know if you still see the OOO.
Interesting. Looks like it depends on which core it runs on. CPU0 is
clean, CPU1 is not.
Clean: taskset --cpu-list 0 ./pfifo_stress.py
Broken: taskset --cpu-list 1 ./pfifo_stress.py
Maybe related: CPU0 is where USB interrupts are handled:
root@rk3399-q7:~# cat /proc/interrupts
CPU0 CPU1 CPU2 CPU3 CPU4 CPU5
217: 2175353 0 0 0 0 0
GICv3 142 Level xhci-hcd:usb5
Thanks,
Jakob
