On Friday, March 16, 2018, 11:26:47 AM CET Jakob Unterwurzacher wrote: > 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
This reminds me somewhat of this thread: https://marc.info/?l=linux-can&m=148007442317274&w=2 Best regards, Alexander
