lkml.org 
[lkml]   [2018]   [Mar]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [bug, bisected] pfifo_fast causes packet reordering
From
Date
Hi,

On Fri, 2018-03-16 at 11:26 +0100, 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


Is not clear to me if you can reproduce the bug with the vanilla
kernel, or if you need some out-of-tree nic driver. Can you please
clarify which NIC/driver are you using?

Thanks,

Paolo

\
 
 \ /
  Last update: 2018-03-19 13:33    [W:0.105 / U:0.112 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site