Re: NET_SCHED cbq dropping too many packets on a bonding interface

[Andrew Morton <akpm@linux-foundation.org>]

(cc netdev)

On Thu, 15 May 2008 12:25:19 +0930 "Kingsley Foreman" <kingsley@internode.com.au> wrote:

> Ive been using qdisc for quite a while without any problems,
> I just rebuilt a gentoo box with 2.6.25 kernel that does a lot of traffic
> ~1000mbits+ over a bonded interface
> 
> Im however seeing a big problem with cbq class dropping packets for no
> reason i can see, and it is causing a lot of speed issues.
> 
> the basic config is this
> _____________________________________________________________________
> /sbin/tc qdisc del dev bond0 root
> /sbin/tc qdisc add dev bond0 root handle 1 cbq bandwidth 2000Mbit avpkt 1000
> cell 8
> /sbin/tc class change dev bond0 root cbq weight 200Mbit allot 1514
> 
> /sbin/tc class add dev bond0 parent 1: classid 1:1280 cbq bandwidth 2000Mbit
> rate 1200Mbit weight 120Mbit prio 1 allot 1514 cell 8 maxburst 120 minburst
> 1 minidle 0 avpkt 1000 bounded
> /sbin/tc filter add dev bond0 parent 1:0 protocol ip prio 300 route to 5
> classid 1:1280
> 
> /sbin/tc class add dev bond0 parent 1: classid 1:1281 cbq bandwidth 2000Mbit
> rate 400Mbit weight 40Mbit prio 6 allot 1514 cell 8 maxburst 120 minburst 1
> minidle 0 avpkt 1000 bounded
> /sbin/tc filter add dev bond0 parent 1:0 protocol ip prio 300 route to 6
> classid 1:1281
> ____________________________________________________________________
> 
> So there is a lot of bandwidth handed out but it is still dropping a lot of
> packets  for very small ammounts of traffic eg 300mbits.
> 
> However the biggest problem im seeing is if i just do this
> 
> __________________________________________________________________
> /sbin/tc qdisc del dev bond0 root
> /sbin/tc qdisc add dev bond0 root handle 1 cbq bandwidth 2000Mbit avpkt 1000
> cell 8
> /sbin/tc class change dev bond0 root cbq weight 200Mbit allot 1514
> ___________________________________________________________________
> 
> after 30sec I get results like
> ___________________________________________________________________
> 
> ### bond0: queueing disciplines
> 
> qdisc cbq 1: root rate 2000Mbit (bounded,isolated) prio no-transmit
>  Sent 574230043 bytes 407156 pkt (dropped 2524, overlimits 0 requeues 0)
>  rate 0bit 0pps backlog 0b 0p requeues 0
>   borrowed 0 overactions 0 avgidle 3 undertime 0
> 
> ### bond0: traffic classes
> 
> class cbq 1: root rate 2000Mbit (bounded,isolated) prio no-transmit
>  Sent 574330783 bytes 407225 pkt (dropped 2525, overlimits 0 requeues 0)
>  rate 0bit 0pps backlog 0b 0p requeues 0
>   borrowed 0 overactions 0 avgidle 3 undertime 0
> __________________________________________________________________
> 
> I can't for the life if me work out why it is dropping so many packets for 
> while doing so little traffic when i enable  cbq the transfer rate drops by 
> approx 30%, any help would be great, and any improvements to my command 
> lines would be good also.
> 
> 
> Kingsley Foreman