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Diffstat (limited to 'Documentation/networking/pktgen.txt')
| -rw-r--r-- | Documentation/networking/pktgen.txt | 56 |
1 files changed, 30 insertions, 26 deletions
diff --git a/Documentation/networking/pktgen.txt b/Documentation/networking/pktgen.txt index 560c84ba9abd..fa0ad87e6597 100644 --- a/Documentation/networking/pktgen.txt +++ b/Documentation/networking/pktgen.txt @@ -3,11 +3,11 @@ HOWTO for the linux packet generator ------------------------------------ -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. +Enable CONFIG_NET_PKTGEN to compile and build pktgen.o either in-kernel +or as a module. A module is preferred; insmod 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: @@ -25,7 +25,7 @@ For monitoring and control pktgen creates: Tuning NIC for max performance ============================== -The default NIC setting are (likely) not tuned for pktgen's artificial +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: @@ -33,20 +33,20 @@ Specifically increasing the TX ring buffer in the NIC: 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 +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 be careful to conclude, that packets/descriptors in the HW +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), thus packets stalling -the TX ring, might just be waiting for cleanup. +ring-buffers for various performance reasons, and 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, +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): +For ixgbe use e.g. "30" resulting in approx 33K interrupts/sec (1/30*10^6): # ethtool -C ethX rx-usecs 30 @@ -58,15 +58,16 @@ 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. +Most important are the devices assigned to the thread. Note that 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: +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 @@ -91,7 +92,8 @@ Result: OK: 13101142(c12220741+d880401) usec, 10000000 (60byte,0frags) Configuring threads and devices ================================ -This is done via the /proc interface easiest done via pgset in the scripts +This is done via the /proc interface, and most easily done via pgset in +the scripts. Examples: @@ -193,7 +195,8 @@ Examples: Example scripts =============== -A collection of small tutorial scripts for pktgen is in examples dir. +A collection of small tutorial scripts for pktgen is in the examples +directory: pktgen.conf-1-1 # 1 CPU 1 dev pktgen.conf-1-2 # 1 CPU 2 dev @@ -204,25 +207,26 @@ 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. +Run in shell: ./pktgen.conf-X-Y +This 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. +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 -could be enabled by simply setting: +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, -user could use "pgset spi SPI_VALUE" to specify which formal of transformation +you can use "pgset spi SPI_VALUE" to specify which transformation mode to employ. |