Commit ca5b542c authored by Ben Hutchings's avatar Ben Hutchings Committed by David S. Miller

pktgen: Fix grammar errors and some poor wording in documentation

Thanks to Rob Jones for suggesting some of the changes.

Cc: Rob Jones <rob.jones@codethink.co.uk>
Signed-off-by: default avatarBen Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 98e688f4
......@@ -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.
......
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