Messages in this thread | | | Subject | Re: [bug, bisected] pfifo_fast causes packet reordering | From | Jakob Unterwurzacher <> | Date | Fri, 16 Mar 2018 11:26:47 +0100 |
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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
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