From mboxrd@z Thu Jan  1 00:00:00 1970
From: Peter Rabbitson <rabbit+list@rabbit.us>
Date: Fri, 26 Oct 2007 22:39:58 +0000
Subject: Re: [LARTC] TC (HTB) doesn't work well when network is congested?
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To: lartc@vger.kernel.org

William Xu wrote:
> Hi Peter, thanks for looking at this.
> 
> Here are the information I got after running tests. The client1 got 
> 7MB/s instead of 40MB/s for SEND,
> and 40MB/s for RECV during the test.
> 
> Thanks,
> william
> 
> # ip link show
> 
> ...
> 5: eth2: <BROADCAST,MULTICAST,UP,LUP> mtu 9000 qdisc htb qlen 1000
>    link/ether 00:e0:ed:04:9f:a2 brd ff:ff:ff:ff:ff:ff
> ...
> 12: ifb0: <BROADCAST,NOARP,UP,LUP> mtu 9000 qdisc htb qlen 32
>    link/ether f2:f2:77:f9:cf:30 brd ff:ff:ff:ff:ff:ff
> 
> #tc qdisc show
> qdisc pfifo_fast 0: dev eth0 root bands 3 priomap  1 2 2 2 1 2 0 0 1 1 1 
> 1 1 1 1 1
> qdisc ingress ffff: dev eth2 ----------------
> qdisc htb 1: dev eth2 r2q 100 default 30 direct_packets_stat 0
> qdisc pfifo_fast 0: dev eth3 root bands 3 priomap  1 2 2 2 1 2 0 0 1 1 1 
> 1 1 1 1 1
> qdisc pfifo_fast 0: dev eth4 root bands 3 priomap  1 2 2 2 1 2 0 0 1 1 1 
> 1 1 1 1 1
> qdisc pfifo_fast 0: dev eth5 root bands 3 priomap  1 2 2 2 1 2 0 0 1 1 1 
> 1 1 1 1 1
> qdisc pfifo_fast 0: dev eth6 root bands 3 priomap  1 2 2 2 1 2 0 0 1 1 1 
> 1 1 1 1 1
> qdisc pfifo_fast 0: dev eth7 root bands 3 priomap  1 2 2 2 1 2 0 0 1 1 1 
> 1 1 1 1 1
> qdisc pfifo_fast 0: dev eth8 root bands 3 priomap  1 2 2 2 1 2 0 0 1 1 1 
> 1 1 1 1 1
> qdisc htb 1: dev ifb0 r2q 100 default 30 direct_packets_stat 0
> 
> #tc -s -d class show dev ifb0
> class htb 1:10 parent 1:1 prio 0 quantum 200000 rate 320000Kbit ceil 
> 960000Kbit burst 169000b/64 mpu 0b overhead 0b cburst 489000b/64 mpu 0b 
> overhead 0b level 0
> Sent 2366125838 bytes 928639 pkt (dropped 0, overlimits 0 requeues 0)
> rate 0bit 0pps backlog 0b 0p requeues 0
> lended: 925807 borrowed: 2832 giants: 0
> tokens: 4224 ctokens: 4075
> 
> class htb 1:1 root rate 960000Kbit ceil 960000Kbit burst 489000b/64 mpu 
> 0b overhead 0b cburst 489000b/64 mpu 0b overhead 0b level 7
> Sent 36927678674 bytes 6132723 pkt (dropped 0, overlimits 0 requeues 0)
> rate 2672bit 1pps backlog 0b 0p requeues 0
> lended: 1131873 borrowed: 0 giants: 0
> tokens: 4074 ctokens: 4074
> 
> class htb 1:30 parent 1:1 prio 1 quantum 200000 rate 640000Kbit ceil 
> 960000Kbit burst 328960b/64 mpu 0b overhead 0b cburst 489000b/64 mpu 0b 
> overhead 0b level 0
> Sent 34561552836 bytes 5204084 pkt (dropped 44, overlimits 0 requeues 0)
> rate 528bit 0pps backlog 0b 0p requeues 0
> lended: 4075043 borrowed: 1129041 giants: 0
> tokens: 4108 ctokens: 4074
> 
> #tc -s -d class show dev eth2
> class htb 1:10 parent 1:1 prio 0 quantum 200000 rate 320000Kbit ceil 
> 960000Kbit burst 169000b/64 mpu 0b overhead 0b cburst 489000b/64 mpu 0b 
> overhead 0b level 0
> Sent 12092794712 bytes 1544210 pkt (dropped 0, overlimits 0 requeues 0)
> rate 56bit 0pps backlog 0b 0p requeues 0
> lended: 1543687 borrowed: 523 giants: 0
> tokens: 4224 ctokens: 4075
> 
> class htb 1:1 root rate 960000Kbit ceil 960000Kbit burst 489000b/64 mpu 
> 0b overhead 0b cburst 489000b/64 mpu 0b overhead 0b level 7
> Sent 36872760531 bytes 7346321 pkt (dropped 0, overlimits 0 requeues 0)
> rate 288bit 0pps backlog 0b 0p requeues 0
> lended: 40477 borrowed: 0 giants: 0
> tokens: 4073 ctokens: 4073
> 
> class htb 1:30 parent 1:1 prio 1 quantum 200000 rate 640000Kbit ceil 
> 960000Kbit burst 328960b/64 mpu 0b overhead 0b cburst 489000b/64 mpu 0b 
> overhead 0b level 0
> Sent 24779965819 bytes 5802111 pkt (dropped 0, overlimits 0 requeues 0)
> rate 176bit 0pps backlog 0b 0p requeues 0
> lended: 5762157 borrowed: 39954 giants: 0
> tokens: 4109 ctokens: 4073
> 
> 

The setup looks good. There are only two things that come to mind - you 
have problems with TSO, or your clock is too slow. For the first use 
ethtool -K to disable all 6 offloading parameters. For the second check 
what is the value of CONFIG_HZ in the current kernel config 
(/boot/config-<your-kernel-version>), and if it is less than 1000 this 
might be your problem as well. If none of those help - I am out of 
ideas, hopefully someone else can help you.

Peter
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