How to use qfq qdisc of tc?

https://access.redhat.com/solutions/1459623

 SOLUTION 已验证 - 已更新 2015年五月26日09:34 - 

English 

环境

• Red Hat Enterprise Linux 6.3 or later
• tc traffic control utility
• qfq Quick Fair Scheduler queueing discipline

问题

• How to use qfq qdisc of tc?
• In Red Hat Enterprise Linux 6.3, the tc utility has been updated to work with the Quick Fair Scheduler (QFQ) kernel features. Users can now take advantage of the new QFQ traffic queuing discipline from userspace. This feature is considered a Technology Preview.

决议

The following bash script is an example of how to add a qdisc, classes, and matches:

Raw

#!/bin/bash

### pass the interface name as a variable if desired
if [ -z "$1" ]; then
    DEV="eth0"
else
    DEV="$1"
fi

### delete any existing qdiscs on the interface
tc qdisc del dev "$DEV" root

### add a root qdisc to the interface
tc qdisc add dev "$DEV" root handle 1: qfq

### add rate limit classes
## here we add two rates, traffic is balanced at a ratio of 100:200 between the two classes
## if using jumboframes, append "maxpkt 9000" onto the end of these
tc class add dev "$DEV" parent 1: classid 1:1 qfq weight 100
tc class add dev "$DEV" parent 1: classid 1:2 qfq weight 200

### match packets into rate limiters
## this matches outgoing ssh into the first rate limiter
tc filter add dev "$DEV" parent 1: protocol all prio 1 u32 match ip dport 22 0xffff flowid 1:1
## match all remaining packets into the second rate limiter
tc filter add dev "$DEV" parent 1: protocol all prio 2 u32 match u32 0 0 flowid 1:2

Results

• View the qdisc active on the interface

Raw

# tc -s -d qdisc show dev eth0
sc qfq 1: root refcnt 2 
 Sent 91325 bytes 468 pkt (dropped 40, overlimits 0 requeues 0) 
  rate 0bit 0pps backlog 0b 0p requeues 0 

• View the classes active on the qdisc

Raw

# tc -s -d class show dev eth0
class qfq 1:1 root weight 1000 maxpkt 1514 
 Sent 10847 bytes 67 pkt (dropped 0, overlimits 0 requeues 0) 
 rate 0bit 0pps backlog 0b 0p requeues 0 
class qfq 1:2 root weight 2000 maxpkt 2962 
 Sent 80720 bytes 402 pkt (dropped 0, overlimits 0 requeues 0) 
 rate 0bit 0pps backlog 0b 0p requeues 0 

• View the filters on the classes

Raw

# tc filter show dev eth0
filter parent 1: protocol all pref 1 u32 
filter parent 1: protocol all pref 1 u32 fh 800: ht divisor 1 
filter parent 1: protocol all pref 1 u32 fh 800::800 order 2048 key ht 800 bkt 0 flowid 1:1 
  match 00000016/0000ffff at 20
filter parent 1: protocol all pref 2 u32 
filter parent 1: protocol all pref 2 u32 fh 801: ht divisor 1 
filter parent 1: protocol all pref 2 u32 fh 801::800 order 2048 key ht 801 bkt 0 flowid 1:2 
  match 00000000/00000000 at 0

Further Reading

Building a more complex classifier chain and classifying traffic into filters is described in the upstream Linux Advanced Routing & Traffic Control HOWTO, the steps are common to any classful qdisc.