Re: Why doesn't the socketcan prio qdisc work for first 10 can frames?

[Oliver Hartkopp <socketcan@hartkopp.net>]

Please try to reduce the tx queue length of the CAN netdevice to 1

E.g.

ip link set can0 txqueuelen 1

Does that help?

Regards,
Oliver

On 27.11.2014 10:43, Ruan TingQuan (ST-FIR/ENG1-Zhu) wrote:
> Hello Linux-can-team,
>
> A prio qdisc is created with 8 bands for my different priority sending requirement.
> My test environment: ubuntu 12.04 (kernel 3.11) + PEAK-USB pro (can0 is connect to can1).
> The frame will be send on can0 and receive on can1 (candump)
> Below is the setting on can0:
> 	> ip link set can0 type can bitrate 5000
> 	> ip link set can1 type can bitrate 5000
> 	> tc qdisc add dev can0 root handle 1: prio bands 8
> 	> tc filter add dev $1 parent 1:0 prio 1 basic match canid\(eff 0x1:0x7\) flowid 1:1
> 	> tc filter add dev $1 parent 1:0 prio 2 basic match canid\(eff 0x2:0x7\) flowid 1:2
> 	> tc filter add dev $1 parent 1:0 prio 3 basic match canid\(eff 0x3:0x7\) flowid 1:3
> 	> tc filter add dev $1 parent 1:0 prio 4 basic match canid\(eff 0x4:0x7\) flowid 1:4
> 	> tc filter add dev $1 parent 1:0 prio 5 basic match canid\(eff 0x5:0x7\) flowid 1:5
> 	> tc filter add dev $1 parent 1:0 prio 6 basic match canid\(eff 0x6:0x7\) flowid 1:6
> 	> tc filter add dev $1 parent 1:0 prio 7 basic match canid\(eff 0x7:0x7\) flowid 1:7
> 	> tc filter add dev $1 parent 1:0 prio 8 basic match canid\(sff 0x0:0x0 eff 0x0:0x0\) flowid 1:8
>
> Then, I made a test program to send 10 frames on can0 socket quickly.
>    	can0  81234560   [8]  00 00 00 00 50 50 50 50
>    	can0  81234567   [8]  07 07 07 07 4F 4F 4F 4F
>    	can0  81234566   [8]  06 06 06 06 4E 4E 4E 4E
>    	can0  81234565   [8]  05 05 05 05 4D 4D 4D 4D
> 	can0  81234564   [8]  04 04 04 04 4C 4C 4C 4C
>    	can0  81234563   [8]  03 03 03 03 4B 4B 4B 4B
>    	can0  81234562   [8]  02 02 02 02 4A 4A 4A 4A
>    	can0  81234561   [8]  01 01 01 01 49 49 49 49
>    	can0  81234560   [8]  00 00 00 00 48 48 48 48
>    	can0  81234567   [8]  07 07 07 07 47 47 47 47
>
> I expect the frames from can1 with priority sequence high to low:
> 	can1  01234560   [8]  00 00 00 00 50 50 50 50
> 	can1  01234561   [8]  01 01 01 01 49 49 49 49
> 	can1  01234562   [8]  02 02 02 02 4A 4A 4A 4A
> 	can1  01234563   [8]  03 03 03 03 4B 4B 4B 4B
> 	can1  01234564   [8]  04 04 04 04 4C 4C 4C 4C
> 	can1  01234565   [8]  05 05 05 05 4D 4D 4D 4D
> 	can1  01234566   [8]  06 06 06 06 4E 4E 4E 4E
> 	can1  01234567   [8]  07 07 07 07 4F 4F 4F 4F
> 	can1  01234560   [8]  00 00 00 00 48 48 48 48
>
> But actually, I got the frames with same sequence
> 	can1  01234560   [8]  00 00 00 00 50 50 50 50
> 	can1  01234567   [8]  07 07 07 07 4F 4F 4F 4F
> 	can1  01234566   [8]  06 06 06 06 4E 4E 4E 4E
> 	can1  01234565   [8]  05 05 05 05 4D 4D 4D 4D
> 	can1  01234564   [8]  04 04 04 04 4C 4C 4C 4C
> 	can1  01234563   [8]  03 03 03 03 4B 4B 4B 4B
> 	can1  01234562   [8]  02 02 02 02 4A 4A 4A 4A
> 	can1  01234561   [8]  01 01 01 01 49 49 49 49
> 	can1  01234560   [8]  00 00 00 00 48 48 48 48
> 	can1  01234567   [8]  07 07 07 07 47 47 47 47
> 	can1  01234566   [8]  06 06 06 06 46 46 46 46
>
> And I found that just happens for first 10 frames. After that, prio qdisc works fine.
> Why? Or What am I missing?
>
> Regards!
> Leo Ruan
>
>
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