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diff --git a/Documentation/networking/pktgen.rst b/Documentation/networking/pktgen.rst new file mode 100644 index 000000000..1225f0f63 --- /dev/null +++ b/Documentation/networking/pktgen.rst @@ -0,0 +1,410 @@ +.. SPDX-License-Identifier: GPL-2.0 + +==================================== +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 [kpktgend_0] + root 130 0.3 0.0 0 0 ? SW 2003 509:50 [kpktgend_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 + + +Kernel threads +============== +Pktgen creates a thread for each CPU with affinity to that CPU. +Which is controlled through procfile /proc/net/pktgen/kpktgend_X. + +Example: /proc/net/pktgen/kpktgend_0:: + + Running: + Stopped: eth4@0 + Result: OK: add_device=eth4@0 + +Most important are the devices assigned to the thread. + +The two basic thread commands are: + + * add_device DEVICE@NAME -- adds a single device + * rem_device_all -- remove all associated devices + +When adding a device to a thread, a corresponding procfile is created +which is used for configuring this device. Thus, device names need to +be unique. + +To support adding the same device to multiple threads, which is useful +with multi queue NICs, the device naming scheme is extended with "@": +device@something + +The part after "@" can be anything, but it is custom to use the thread +number. + +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/eth4@0 + + Params: count 100000 min_pkt_size: 60 max_pkt_size: 60 + frags: 0 delay: 0 clone_skb: 64 ifname: eth4@0 + flows: 0 flowlen: 0 + queue_map_min: 0 queue_map_max: 0 + dst_min: 192.168.81.2 dst_max: + src_min: src_max: + src_mac: 90:e2:ba:0a:56:b4 dst_mac: 00:1b:21:3c:9d:f8 + udp_src_min: 9 udp_src_max: 109 udp_dst_min: 9 udp_dst_max: 9 + src_mac_count: 0 dst_mac_count: 0 + Flags: UDPSRC_RND NO_TIMESTAMP QUEUE_MAP_CPU + Current: + pkts-sofar: 100000 errors: 0 + started: 623913381008us stopped: 623913396439us idle: 25us + seq_num: 100001 cur_dst_mac_offset: 0 cur_src_mac_offset: 0 + cur_saddr: 192.168.8.3 cur_daddr: 192.168.81.2 + cur_udp_dst: 9 cur_udp_src: 42 + cur_queue_map: 0 + flows: 0 + Result: OK: 15430(c15405+d25) usec, 100000 (60byte,0frags) + 6480562pps 3110Mb/sec (3110669760bps) errors: 0 + + +Configuring devices +=================== +This is done via the /proc interface, and most easily done via pgset +as defined in the sample scripts. +You need to specify PGDEV environment variable to use functions from sample +scripts, i.e.:: + + export PGDEV=/proc/net/pktgen/eth4@0 + source samples/pktgen/functions.sh + +Examples:: + + pg_ctrl start starts injection. + pg_ctrl stop aborts injection. Also, ^C aborts generator. + + 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 + NO_TIMESTAMP # disable timestamping + pgset 'flag ![name]' Clear a flag to determine behaviour. + Note that you might need to use single quote in + interactive mode, so that your shell wouldn't expand + the specified flag as a history command. + + 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 "rate 300M" set rate to 300 Mb/s + pgset "ratep 1000000" set rate to 1Mpps + + pgset "xmit_mode netif_receive" RX inject into stack netif_receive_skb() + Works with "burst" but not with "clone_skb". + Default xmit_mode is "start_xmit". + +Sample scripts +============== + +A collection of tutorial scripts and helpers for pktgen is in the +samples/pktgen directory. The helper parameters.sh file support easy +and consistent parameter parsing across the sample scripts. + +Usage example and help:: + + ./pktgen_sample01_simple.sh -i eth4 -m 00:1B:21:3C:9D:F8 -d 192.168.8.2 + +Usage::: + + ./pktgen_sample01_simple.sh [-vx] -i ethX + + -i : ($DEV) output interface/device (required) + -s : ($PKT_SIZE) packet size + -d : ($DEST_IP) destination IP. CIDR (e.g. 198.18.0.0/15) is also allowed + -m : ($DST_MAC) destination MAC-addr + -p : ($DST_PORT) destination PORT range (e.g. 433-444) is also allowed + -t : ($THREADS) threads to start + -f : ($F_THREAD) index of first thread (zero indexed CPU number) + -c : ($SKB_CLONE) SKB clones send before alloc new SKB + -n : ($COUNT) num messages to send per thread, 0 means indefinitely + -b : ($BURST) HW level bursting of SKBs + -v : ($VERBOSE) verbose + -x : ($DEBUG) debug + -6 : ($IP6) IPv6 + -w : ($DELAY) Tx Delay value (ns) + -a : ($APPEND) Script will not reset generator's state, but will append its config + +The global variables being set are also listed. E.g. the required +interface/device parameter "-i" sets variable $DEV. Copy the +pktgen_sampleXX scripts and modify them to fit your own needs. + + +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. + +Plus using the device flag QUEUE_MAP_CPU, which maps the SKBs TX queue +to the running threads CPU (directly from smp_processor_id()). + +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 + reset + +**Thread commands**:: + + add_device + rem_device_all + + +**Device commands**:: + + count + clone_skb + burst + debug + + frags + delay + + src_mac_count + dst_mac_count + + pkt_size + min_pkt_size + max_pkt_size + + queue_map_min + queue_map_max + skb_priority + + tos (ipv4) + traffic_class (ipv6) + + mpls + + udp_src_min + udp_src_max + + udp_dst_min + udp_dst_max + + node + + 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 + NO_TIMESTAMP + + spi (ipsec) + + dst_min + dst_max + + src_min + src_max + + dst_mac + src_mac + + clear_counters + + src6 + dst6 + dst6_max + dst6_min + + flows + flowlen + + rate + ratep + + xmit_mode <start_xmit|netif_receive> + + vlan_cfi + vlan_id + vlan_p + + svlan_cfi + svlan_id + svlan_p + + +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. |