table of contents
netpipe(1) | netpipe | netpipe(1) |
NAME¶
NetPIPE - Network Protocol Independent Performance EvaluatorSYNOPSIS¶
NPtcp [-h receiver_hostname] [-b TCP_buffer_sizes] [options]DESCRIPTION¶
Comparing the latency and maximum throughput of various network cards.
Comparing the performance between different types of networks.
Looking for inefficiencies in the message-passing layer by comparing it to the
native communication layer.
Optimizing the message-passing layer and tune OS and driver parameters for
optimal performance of the communication subsystem.
TESTING TCP¶
NPtcp can now be launched in two ways, by manually starting NPtcp on both systems or by using a nplaunch script. To manually start NPtcp, the NetPIPE receiver must be started first on the remote system using the command: NPtcp [options] then the primary transmitter is started on the local system with the command NPtcp -h receiver_hostname [options] Any options used must be the same on both sides.option sets the TCP socket buffer size, which can greatly influence the maximum throughput on some systems. A throughput graph that flattens out suddenly may be a sign of the performance being limited by the socket buffer sizes.
TESTING MPI and MPI-2¶
Use of the MPI interface for NetPIPE depends on the MPI implementation being used. All will require the number of processes to be specified, usually with a -np 2 argument. Clusters environments may require a list of the hosts being used when each job is run. Put the list of hosts in hostlist then, for OpenMPI, run NetPIPE using: mpirun --hostfile hostlist -np 2 NPmpi [NetPIPE options]TESTING PVM¶
Start the pvm system using: pvm and adding a second machine with the PVM command add receiver_hostname Exit the PVM command line interface using quit, then run the PVM NetPIPE receiver on one system with the command: NPpvm [options] and run the TCP NetPIPE transmitter on the other system with the command: NPpvm -h receiver hostname [options] Any options used must be the same on both sides. The nplaunch script may also be used with NPpvm as described above for NPtcp.TESTING METHODOLOGY¶
NetPIPE tests network performance by sending a number of messages at each block size, starting from the lower bound on the message sizes.output file may be graphed using a program such as gnuplot(1). The output file contains three columns: the number of bytes in the block, the transfer rate in bits per second, and the time to transfer the block (half the round-trip time). The first two columns are normally used to graph the throughput vs block size, while the third column provides the latency. For example, the throughput versus block size graph can be created by graphing bytes versus bits per second. Sample gnuplot(1) commands for such a graph would be set logscale x plot "np.out"
OPTIONS¶
- -a
- asynchronous mode: prepost receives (MPI, IB modules)
- -b TCP_buffer_sizes
- Set the send and receive TCP buffer sizes (TCP module
only).
- -B
- Burst mode where all receives are preposted at once (MPI,
IB modules).
- -f
- Use a fence to block for completion (MPI2 module only).
- -g
- Use MPI_Get() instead of MPI_Put() (MPI2 module only).
- -h hostname
- Specify the name of the receiver host to connect to (TCP,
PVM, IB, GM).
- -I
- Invalidate cache to measure performance without cache
effects (mostly affects IB and memcpy modules).
- -i
- Do an integrity check instead of a performance evaluation.
- -l starting_msg_size
- Specify the lower bound for the size of messages to be tested.
- -n nrepeats
- Set the number of repeats for each test to a constant.
Otherwise, the number of repeats is chosen to provide an accurate timing
for each test. Be very careful if specifying a low number so that the time
for the ping-pong test exceeds the timer accuracy.
- -O source_offset,dest_offset
- Specify the source and destination offsets of the buffers from perfect page alignment.
-
- Specify the output filename (default is np.out).
- -p perturbation_size
- NetPIPE chooses the message sizes at regular intervals,
increasing them exponentially from the lower boundary to the upper
boundary. At each point, it also tests perturbations of 3 bytes above and
3 bytes below each test point to find idiosyncrasies in the system. This
perturbation value can be changed using the -p option, or turned
off using -p 0 .
- -r
- This option resets the TCP sockets after every test (TCP
module only). It is necessary for some streaming tests to get good
measurements since the socket window size may otherwise collapse.
- -s
- Set streaming mode where data is only transmitted in one
direction.
- -S
- Use synchronous sends (MPI module only).
- -u upper_bound
- Specify the upper boundary to the size of message being
tested. By default, NetPIPE will stop when the time to transmit a block
exceeds one second.
- -z
- Receive messages using MPI_ANY_SOURCE (MPI module only)
- -2
- Set bi-directional mode where both sides send and receive
at the same time (supported by most modules). You may need to use
-a to choose asynchronous communications for MPI to avoid
freeze-ups. For TCP, the maximum test size will be limited by the TCP
buffer sizes.
FILES¶
- np.out
- Default output file for NetPIPE. Overridden by the
-o option.
AUTHOR¶
The original NetPIPE core plus TCP and MPI modules were written by Quinn Snell, Armin Mikler, Guy Helmer, and John Gustafson. NetPIPE is currently being developed and maintained by Dave Turner with contributions from many students (Bogdan Vasiliu, Adam Oline, Xuehua Chen, and Brian Smith).BUGS¶
As of version 3.6.1, there is a bug that causes NetPIPE to segfault on RedHat Enterprise systems. I will debug this as soon as I get access to a few such systems. -Dave Turner (turner@ameslab.gov)June 1, 2004 | NetPIPE |