Messages in this thread | | | From | Jakob Unterwurzacher <> | Subject | Re: [bug, bisected] pfifo_fast causes packet reordering | Date | Wed, 14 Mar 2018 11:09:02 +0100 |
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On 14.03.18 05:03, John Fastabend wrote: >>> During stress-testing our "ucan" USB/CAN adapter SocketCAN driver on Linux >>> v4.16-rc4-383-ged58d66f60b3 we observed that a small fraction of packets are >>> delivered out-of-order. >>> > > Is the stress-testing tool available somewhere? What type of packets > are being sent?
Not public, no, the problem is that you'd need a CAN adapter as well.
The test is simple, sending CAN frames with an increasing counter and a random length payload:
[ tx thread rx thread ] | ^ v | [ interface 0 ] ---- cable ----> [ interface 1 ]
I'll see if I can come up with a UDP testcase that works with normal ethernet interfaces.
> Is this a single queue device or a multiqueue device? Running > 'tc -s qdisc show dev foo' would help some.
Here you go:
root@rk3399-q7:~# tc -s qdisc show dev can0 qdisc pfifo_fast 0: root refcnt 2 bands 3 priomap 1 2 2 2 1 2 0 0 1 1 1 1 1 1 1 1 Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0) backlog 0b 0p requeues 0
> If we introduced a OOO edge case somewhere that was not > intended so I'll take a look into it. But, if you can provide > a bit more details on how stress testing is done to cause the > issue that would help.
Will do.
Thanks, Jakob
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