Ubuntu Manpage: NetPIPE - Network Protocol Independent Performance Evaluator

Provided by: netpipe-lam_3.7.2-7build1_amd64

NAME

       NetPIPE - Network Protocol Independent Performance Evaluator

SYNOPSIS

       NPtcp [-h receiver_hostname] [-b TCP_buffer_sizes] [options]

       mpirun [-machinefile hostlist] -np 2 NPmpi [-a] [-S] [-z] [options]

       mpirun [-machinefile hostlist] -np 2 NPmpi2 [-f] [-g] [options]

       NPpvm [options]

       See  the  TESTING  sections below for a more complete description of how to run NetPIPE in
       each environment.  The OPTIONS section describes the general  options  available  for  all
       modules.       See      the      README      file      from      the      tar-ball      at
       http://www.scl.ameslab.gov/Projects/NetPIPE/ for  documentation  on  the  InfiniBand,  GM,
       SHMEM, LAPI, and memcpy modules.

DESCRIPTION

NetPIPE uses a simple series of ping-pong tests over a range of message sizes to provide a
complete measure of the performance of a network. It bounces messages of increasing size
between two processes, whether across a network or within an SMP system. Message sizes
are chosen at regular intervals, and with slight perturbations, to provide a complete
evaluation of the communication system. Each data point involves many ping-pong tests to
provide an accurate timing. Latencies are calculated by dividing the round trip time in
half for small messages ( less than 64 Bytes ).

The communication time for small messages is dominated by the overhead in the
communication layers, meaning that the transmission is latency bound. For larger
messages, the communication rate becomes bandwidth limited by some component in the
communication subsystem (PCI bus, network card link, network switch).

These measurements can be done at the message-passing layer (MPI, MPI-2, and PVM) or at
the native communications layers that that run upon (TCP/IP, GM for Myrinet cards,
InfiniBand, SHMEM for the Cray T3E systems, and LAPI for IBM SP systems). Recent work is
being aimed at measuring some internal system properties such as the memcpy module that
measures the internal memory copy rates, or a disk module under development that measures
the performance to various I/O devices.

Some uses for NetPIPE include:

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.

NetPIPE is provided with many modules allowing it to interface with a wide variety of
communication layers. It is fairly easy to write new interfaces for other reliable
protocols by using the existing modules as examples.

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.

       The  nplaunch  script  uses  ssh  to  launch the remote receiver before starting the local
       transmitter.  To use rsh, simply change the nplaunch script.

       nplaunch NPtcp -h receiver_hostname [options]

       The -b TCP_buffer_sizes 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]

       For MPICH2 use instead:

       mpirun -machinefile hostlist -np 2 NPmpi [NetPIPE options]

       To test the 1-sided communications of the MPI-2 standard, compile using:

       make mpi2

       Running  as  described  above and MPI will use 1-sided MPI_Put() calls in both directions,
       with each receiver blocking until the last byte has been overwritten before  bouncing  the
       message  back.   Use  the  -f  option  to  force  usage of a fence to block rather than an
       overwrite of the last byte.  The -g option will use MP_Get()  functions  to  transfer  the
       data rather than MP_Put().

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.

       The message size is incremented until the upper bound on the message size  is  reached  or
       the  time  to transmit a block exceeds one second, which ever occurs first.  Message sizes
       are chosen at regular intervals, and for slight perturbations from them to provide a  more
       complete evaluation of the communication subsystem.

       The  NetPIPE  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.

-o output_filename
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).

       Send comments/bug-reports to: <netpipe@scl.ameslab.gov>.

       Additional   information   about   NetPIPE   can  be  found  on  the  World  Wide  Web  at
       http://www.scl.ameslab.gov/Projects/NetPIPE/

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)