HOWTO for the linux packet generator ------------------------------------ Date: 041221 Enable CONFIG_NET_PKTGEN to compile and build pktgen.o either in kernel or as module. Module is preferred. insmod pktgen if needed. Once running pktgen creates a thread on each CPU where each thread has affinity to its CPU. Monitoring and controlling is done via /proc. Easiest to select a suitable a sample script and configure. 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 setting 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 CPUs L1/L2 cache, 2) because it allow more queueing in the NIC HW layer (which is bad for bufferbloat). One should be careful to conclude, that packets/descriptors in the HW TX ring cause delay. Drivers usually delay cleaning up the ring-buffers (for various performance reasons), thus packets stalling the TX ring, might just be waiting for cleanup. This cleanup issues is specifically the case, for the driver ixgbe (Intel 82599 chip). This driver (ixgbe) combine 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 the devices assigned to thread. Note! A device can only belong to one thread. Viewing devices =============== Parm section holds configured info. Current hold running stats. Result is printed after 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 easiest done via pgset in the 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 "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 Example scripts =============== A collection of small tutorial scripts for pktgen is in examples dir. 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 It does all the setup including sending. Interrupt affinity =================== Note when adding devices to a specific CPU there good idea to also assign /proc/irq/XX/smp_affinity so the TX-interrupts gets bound to the same CPU. as this reduces cache bouncing when freeing skb's. Enable IPsec ============ Default IPsec transformation with ESP encapsulation plus Transport mode could be enabled by simply setting: pgset "flag IPSEC" pgset "flows 1" To avoid breaking existing testbed scripts for using AH type and tunnel mode, user could use "pgset spi SPI_VALUE" to specify which formal of transformation 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.