Hi!

I've been using HTB in a Linux bridge and recently I noticed that, for

high speed, the configured rate/ceil is not respected as for lower

speeds.

I'm using a packet generator/analyser to inject over 950Mpbs, and see

what returns back to it, in the other side of my bridge. Generated

packets have 800bytes. I noticed that, for several tc HTB rate/ceil

configurations the amount of traffic received by the analyser stays

the same. See this values:
HTB conf      Analyser reception

476000Kbit    544.260.329

500000Kbit    545.880.017

510000Kbit    544.489.469

512000Kbit    546.890.972

-------------------------

513000Kbit    596.061.383

520000Kbit    596.791.866

550000Kbit    596.543.271

554000Kbit    596.193.545

-------------------------

555000Kbit    654.773.221

570000Kbit    654.996.381

590000Kbit    655.363.253

605000Kbit    654.112.017

-------------------------

606000Kbit    728.262.237

665000Kbit    727.014.365

-------------------------
There are these steps and it looks like doesn't matter if I configure

HTB to 555Mbit or to 605Mbit - the result is the same: 654Mbit. This

is 18% more traffic than the configured value. I also realise that for

smaller packets it gets worse, reaching 30% more traffic than what I

configured. For packets of 1514bytes the accuracy is quiet good.

I'm using kernel 2.6.25
My 'tc -s -d class ls dev eth1' output:
class htb 1:10 parent 1:2 rate 1000Mbit ceil 1000Mbit burst 126375b/8

mpu 0b overhead 0b cburst 126375b/8 mpu 0b overhead 0b level 5

 Sent 51888579644 bytes 62067679 pkt (dropped 0, overlimits 0 requeues 0)

 rate 653124Kbit 97656pps backlog 0b 0p requeues 0

 lended: 0 borrowed: 0 giants: 0

 tokens: 113 ctokens: 113
class htb 1:1 root rate 1000Mbit ceil 1000Mbit burst 126375b/8 mpu 0b

overhead 0b cburst 126375b/8 mpu 0b overhead 0b level 7

 Sent 51888579644 bytes 62067679 pkt (dropped 0, overlimits 0 requeues 0)

 rate 653123Kbit 97656pps backlog 0b 0p requeues 0

 lended: 0 borrowed: 0 giants: 0

 tokens: 113 ctokens: 113
class htb 1:2 parent 1:1 rate 1000Mbit ceil 1000Mbit burst 126375b/8

mpu 0b overhead 0b cburst 126375b/8 mpu 0b overhead 0b level 6

 Sent 51888579644 bytes 62067679 pkt (dropped 0, overlimits 0 requeues 0)

 rate 653124Kbit 97656pps backlog 0b 0p requeues 0

 lended: 0 borrowed: 0 giants: 0

 tokens: 113 ctokens: 113
class htb 1:108 parent 1:10 leaf 108: prio 7 quantum 1514 rate

555000Kbit ceil 555000Kbit burst 70901b/8 mpu 0b overhead 0b cburst

70901b/8 mpu 0b overhead 0b level 0

 Sent 51888579644 bytes 62067679 pkt (dropped 27801917, overlimits 0 requeues 0)

 rate 653124Kbit 97656pps backlog 0b 0p requeues 0

 lended: 62067679 borrowed: 0 giants: 0

 tokens: -798 ctokens: -798
As you can see, class htb 1:108 rate's is 653124Kbit! Much bigger that

it's ceil.
I also note that, for HTB rate configurations over 500Mbit/s on leaf

class, when I stop the traffic, in the output of "tc -s -d class ls

dev eth1" command, I see that leaf's rate (in bits/s) is growing

instead of decreasing (as expected since I've stopped the traffic).

Rate in pps is ok and decreases until 0pps. Rate in bits/s increases

above 1000Mbit and stays there for a few minutes. After two or three

minutes it becomes 0bit. The same happens for it's ancestors (also for

root class).Here's tc output of my leaf class for this situation:
class htb 1:108 parent 1:10 leaf 108: prio 7 quantum 1514 rate

555000Kbit ceil 555000Kbit burst 70901b/8 mpu 0b overhead 0b cburst

70901b/8 mpu 0b overhead 0b level 0

 Sent 120267768144 bytes 242475339 pkt (dropped 62272599, overlimits 0

requeues 0)

 rate 1074Mbit 0pps backlog 0b 0p requeues 0

 lended: 242475339 borrowed: 0 giants: 0

 tokens: 8 ctokens: 8
  Antonio Almeida

--

To unsubscribe from this list: send the line "unsubscribe netdev" in

the body of a message to majordomo@vger.kernel.org

More majordomo info at  http://vger.kernel.org/majordomo-info.html