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HOWTO for the linux packet generator
------------------------------------
Enable CONFIG_NET_PKTGEN to compile and build pktgen either in-kernel
or as a module. A module is preferred; modprobe pktgen if needed. Once
running, pktgen creates a thread for each CPU with affinity to that CPU.
Monitoring and controlling is done via /proc. It is easiest to select a
suitable sample script and configure that.
On a dual CPU:
ps aux | grep pkt
root 129 0.3 0.0 0 0 ? SW 2003 523:20 [pktgen/0]
root 130 0.3 0.0 0 0 ? SW 2003 509:50 [pktgen/1]
For monitoring and control pktgen creates:
/proc/net/pktgen/pgctrl
/proc/net/pktgen/kpktgend_X
/proc/net/pktgen/ethX
Tuning NIC for max performance
==============================
The default NIC settings are (likely) not tuned for pktgen's artificial
overload type of benchmarking, as this could hurt the normal use-case.
Specifically increasing the TX ring buffer in the NIC:
# ethtool -G ethX tx 1024
A larger TX ring can improve pktgen's performance, while it can hurt
in the general case, 1) because the TX ring buffer might get larger
than the CPU's L1/L2 cache, 2) because it allows more queueing in the
NIC HW layer (which is bad for bufferbloat).
One should hesitate to conclude that packets/descriptors in the HW
TX ring cause delay. Drivers usually delay cleaning up the
ring-buffers for various performance reasons, and packets stalling
the TX ring might just be waiting for cleanup.
This cleanup issue is specifically the case for the driver ixgbe
(Intel 82599 chip). This driver (ixgbe) combines TX+RX ring cleanups,
and the cleanup interval is affected by the ethtool --coalesce setting
of parameter "rx-usecs".
For ixgbe use e.g. "30" resulting in approx 33K interrupts/sec (1/30*10^6):
# ethtool -C ethX rx-usecs 30
Viewing threads
===============
/proc/net/pktgen/kpktgend_0
Name: kpktgend_0 max_before_softirq: 10000
Running:
Stopped: eth1
Result: OK: max_before_softirq=10000
Most important are the devices assigned to the thread. Note that a
device can only belong to one thread.
Viewing devices
===============
The Params section holds configured information. The Current section
holds running statistics. The Result is printed after a run or after
interruption. Example:
/proc/net/pktgen/eth1
Params: count 10000000 min_pkt_size: 60 max_pkt_size: 60
frags: 0 delay: 0 clone_skb: 1000000 ifname: eth1
flows: 0 flowlen: 0
dst_min: 10.10.11.2 dst_max:
src_min: src_max:
src_mac: 00:00:00:00:00:00 dst_mac: 00:04:23:AC:FD:82
udp_src_min: 9 udp_src_max: 9 udp_dst_min: 9 udp_dst_max: 9
src_mac_count: 0 dst_mac_count: 0
Flags:
Current:
pkts-sofar: 10000000 errors: 39664
started: 1103053986245187us stopped: 1103053999346329us idle: 880401us
seq_num: 10000011 cur_dst_mac_offset: 0 cur_src_mac_offset: 0
cur_saddr: 0x10a0a0a cur_daddr: 0x20b0a0a
cur_udp_dst: 9 cur_udp_src: 9
flows: 0
Result: OK: 13101142(c12220741+d880401) usec, 10000000 (60byte,0frags)
763292pps 390Mb/sec (390805504bps) errors: 39664
Configuring threads and devices
================================
This is done via the /proc interface, and most easily done via pgset
as defined in the sample scripts.
Examples:
pgset "clone_skb 1" sets the number of copies of the same packet
pgset "clone_skb 0" use single SKB for all transmits
pgset "burst 8" uses xmit_more API to queue 8 copies of the same
packet and update HW tx queue tail pointer once.
"burst 1" is the default
pgset "pkt_size 9014" sets packet size to 9014
pgset "frags 5" packet will consist of 5 fragments
pgset "count 200000" sets number of packets to send, set to zero
for continuous sends until explicitly stopped.
pgset "delay 5000" adds delay to hard_start_xmit(). nanoseconds
pgset "dst 10.0.0.1" sets IP destination address
(BEWARE! This generator is very aggressive!)
pgset "dst_min 10.0.0.1" Same as dst
pgset "dst_max 10.0.0.254" Set the maximum destination IP.
pgset "src_min 10.0.0.1" Set the minimum (or only) source IP.
pgset "src_max 10.0.0.254" Set the maximum source IP.
pgset "dst6 fec0::1" IPV6 destination address
pgset "src6 fec0::2" IPV6 source address
pgset "dstmac 00:00:00:00:00:00" sets MAC destination address
pgset "srcmac 00:00:00:00:00:00" sets MAC source address
pgset "queue_map_min 0" Sets the min value of tx queue interval
pgset "queue_map_max 7" Sets the max value of tx queue interval, for multiqueue devices
To select queue 1 of a given device,
use queue_map_min=1 and queue_map_max=1
pgset "src_mac_count 1" Sets the number of MACs we'll range through.
The 'minimum' MAC is what you set with srcmac.
pgset "dst_mac_count 1" Sets the number of MACs we'll range through.
The 'minimum' MAC is what you set with dstmac.
pgset "flag [name]" Set a flag to determine behaviour. Current flags
are: IPSRC_RND # IP source is random (between min/max)
IPDST_RND # IP destination is random
UDPSRC_RND, UDPDST_RND,
MACSRC_RND, MACDST_RND
TXSIZE_RND, IPV6,
MPLS_RND, VID_RND, SVID_RND
FLOW_SEQ,
QUEUE_MAP_RND # queue map random
QUEUE_MAP_CPU # queue map mirrors smp_processor_id()
UDPCSUM,
IPSEC # IPsec encapsulation (needs CONFIG_XFRM)
NODE_ALLOC # node specific memory allocation
pgset spi SPI_VALUE Set specific SA used to transform packet.
pgset "udp_src_min 9" set UDP source port min, If < udp_src_max, then
cycle through the port range.
pgset "udp_src_max 9" set UDP source port max.
pgset "udp_dst_min 9" set UDP destination port min, If < udp_dst_max, then
cycle through the port range.
pgset "udp_dst_max 9" set UDP destination port max.
pgset "mpls 0001000a,0002000a,0000000a" set MPLS labels (in this example
outer label=16,middle label=32,
inner label=0 (IPv4 NULL)) Note that
there must be no spaces between the
arguments. Leading zeros are required.
Do not set the bottom of stack bit,
that's done automatically. If you do
set the bottom of stack bit, that
indicates that you want to randomly
generate that address and the flag
MPLS_RND will be turned on. You
can have any mix of random and fixed
labels in the label stack.
pgset "mpls 0" turn off mpls (or any invalid argument works too!)
pgset "vlan_id 77" set VLAN ID 0-4095
pgset "vlan_p 3" set priority bit 0-7 (default 0)
pgset "vlan_cfi 0" set canonical format identifier 0-1 (default 0)
pgset "svlan_id 22" set SVLAN ID 0-4095
pgset "svlan_p 3" set priority bit 0-7 (default 0)
pgset "svlan_cfi 0" set canonical format identifier 0-1 (default 0)
pgset "vlan_id 9999" > 4095 remove vlan and svlan tags
pgset "svlan 9999" > 4095 remove svlan tag
pgset "tos XX" set former IPv4 TOS field (e.g. "tos 28" for AF11 no ECN, default 00)
pgset "traffic_class XX" set former IPv6 TRAFFIC CLASS (e.g. "traffic_class B8" for EF no ECN, default 00)
pgset stop aborts injection. Also, ^C aborts generator.
pgset "rate 300M" set rate to 300 Mb/s
pgset "ratep 1000000" set rate to 1Mpps
Sample scripts
==============
A collection of small tutorial scripts for pktgen is in the
samples/pktgen directory:
pktgen.conf-1-1 # 1 CPU 1 dev
pktgen.conf-1-2 # 1 CPU 2 dev
pktgen.conf-2-1 # 2 CPU's 1 dev
pktgen.conf-2-2 # 2 CPU's 2 dev
pktgen.conf-1-1-rdos # 1 CPU 1 dev w. route DoS
pktgen.conf-1-1-ip6 # 1 CPU 1 dev ipv6
pktgen.conf-1-1-ip6-rdos # 1 CPU 1 dev ipv6 w. route DoS
pktgen.conf-1-1-flows # 1 CPU 1 dev multiple flows.
Run in shell: ./pktgen.conf-X-Y
This does all the setup including sending.
Interrupt affinity
===================
Note that when adding devices to a specific CPU it is a good idea to
also assign /proc/irq/XX/smp_affinity so that the TX interrupts are bound
to the same CPU. This reduces cache bouncing when freeing skbs.
Enable IPsec
============
Default IPsec transformation with ESP encapsulation plus transport mode
can be enabled by simply setting:
pgset "flag IPSEC"
pgset "flows 1"
To avoid breaking existing testbed scripts for using AH type and tunnel mode,
you can use "pgset spi SPI_VALUE" to specify which transformation mode
to employ.
Current commands and configuration options
==========================================
** Pgcontrol commands:
start
stop
** Thread commands:
add_device
rem_device_all
max_before_softirq
** Device commands:
count
clone_skb
debug
frags
delay
src_mac_count
dst_mac_count
pkt_size
min_pkt_size
max_pkt_size
mpls
udp_src_min
udp_src_max
udp_dst_min
udp_dst_max
flag
IPSRC_RND
IPDST_RND
UDPSRC_RND
UDPDST_RND
MACSRC_RND
MACDST_RND
TXSIZE_RND
IPV6
MPLS_RND
VID_RND
SVID_RND
FLOW_SEQ
QUEUE_MAP_RND
QUEUE_MAP_CPU
UDPCSUM
IPSEC
NODE_ALLOC
dst_min
dst_max
src_min
src_max
dst_mac
src_mac
clear_counters
dst6
src6
flows
flowlen
rate
ratep
References:
ftp://robur.slu.se/pub/Linux/net-development/pktgen-testing/
ftp://robur.slu.se/pub/Linux/net-development/pktgen-testing/examples/
Paper from Linux-Kongress in Erlangen 2004.
ftp://robur.slu.se/pub/Linux/net-development/pktgen-testing/pktgen_paper.pdf
Thanks to:
Grant Grundler for testing on IA-64 and parisc, Harald Welte, Lennert Buytenhek
Stephen Hemminger, Andi Kleen, Dave Miller and many others.
Good luck with the linux net-development.
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