linux-kernel - NET_SCHED cbq dropping too many packets on a bonding interface

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Date:	Thu, 15 May 2008 12:25:19 +0930
From:	"Kingsley Foreman" <kingsley@...ernode.com.au>
To:	<linux-kernel@...r.kernel.org>
Subject: NET_SCHED cbq dropping too many packets on a bonding interface

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
 

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