Messages in this thread | | | From | Alexander Stein <> | Subject | Re: [bug, bisected] pfifo_fast causes packet reordering | Date | Mon, 19 Mar 2018 07:07:05 +0100 |
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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
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