Description

The kernel module of PIAS (Practical Information-Agnostic flow Scheduling). The kernel module matains the per-flow state (flow.h and flow.c) and marks packets with different priorities (DSCP) (network.h and network.c).

Compiling

I have tested this kernel module with Linux kernel 2.6.38.3 and 3.18.11. You need the kernel headers to compile it:

$ cd pias4

$ make

Then you can get a kernel module called pias.ko.

Installing

pias.ko hooks into the data path using Netfilter hooks. To install it:

$ insmod pias.ko

$ dmesg|tail

PIAS: start on any interface (TCP port 0)

By default, pias.ko filters all TCP packets (0=all) on all NICs. You can also specify the NIC and TCP port number. For exmaple, to make pias.ko only filters TCP packets whose (source or destination) port numbers are 5001 on eth1:

$ insmod pias.ko param_dev=eth1 param_port=5001

$ dmesg|tail

PIAS: start on eth1 (TCP port 5001)

To remove the packet tagging module:

$ rmmod pias

$ dmesg|tail

PIAS: stop working

Usage

PIAS packet tagging module exports two types of configurations interfaces: a sysfs file to control flow table and several sysctl interfaces to configure priority parameters (see params.h and params.c for their definitions).

To print the information of all flows in current flow table:

$ echo -n print > /sys/module/pias/parameters/param_table_operation

$ dmesg|tail

PIAS: current flow table

PIAS: flowlist 136

PIAS: flow record from 192.168.101.11:60410 to 192.168.101.12:5001, bytes_sent=481926280, seq=2365093177, ACK=2364897698

PIAS: flowlist 160

PIAS: flow record from 192.168.101.11:60411 to 192.168.101.12:5001, bytes_sent=578661368, seq=3795198569, ACK=3794930690

PIAS: flowlist 184

PIAS: flow record from 192.168.101.11:60412 to 192.168.101.12:5001, bytes_sent=385470656, seq=3374872543, ACK=3374742224

PIAS: flowlist 208

PIAS: flow record from 192.168.101.11:60413 to 192.168.101.12:5001, bytes_sent=433638376, seq=215506294, ACK=215310815

PIAS: there are 4 flows in total

To clear all the information in current flow table:

$ echo -n clear > /sys/module/pias/parameters/param_table_operation

To show the DSCP value of highest priority:

$ sysctl pias.prio_dscp_0

pias.prio_dscp_0 = 0

To set the first demoting threshold to 50KB:

$ sysctl -w pias.prio_thresh_0=51200