NETTEST(8) BSD System Manager's Manual NETTEST(8)NAMEnettest - Perform client functions for timing data throughput
nettestd - Perform server functions for timing data throughput
SYNOPSISnettest [-cCdfFhmw] [-b bufsize] [-n conns] [-p tcp|udp|iso] [-s n] [-S
tos] [host [count [size [ port ]]]]
nettest [-cCdfhw] [-b bufsize] -p local|locald|pipe [-n conns] [count
[size [filename]]]
nettest [-cCdfh] [-b bufsize] -p file writefile readfile [count [size]]
nettest-V
nettestd [-d] [-p tcp|udp|iso] [port]
nettestd [-d] -p local|locald|pipe [filename]
nettestd [-d] -p file readfile writefile
nettestd -V
DESCRIPTION
The nettest and nettestd commands invoke client and server programs that
are used for timing data throughput of various methods of interprocess
communication. For TCP and OSI connections, the nettest program estab-
lishes a connection with the nettestd program, and then it does count
writes of size bytes, followed by count reads of size bytes. For UDP,
the nettest program performs only writes; reads are not performed. The
nettestd program, if used with UDP connections, reads the data packets
and prints a message for each data packet it receives. The number and
size of the reads and writes may not correlate with the number and size
of the actual data packets that are transferred; it depends on the proto-
col that is chosen. If you append an optional k (or K) to the size,
count, or bufsize value, the number specified is multiplied by 1024.
The nettest and nettestd commands accept the following arguments:
-b bufsize
This option applies only to nettest. For TCP and UDP connections,
use the -b option to specify the amount of kernel buffering al-
lowed.
-b This option applies only to nettestd. Run as a background daemon.
In this mode, nettestd will detach itself from its controlling
terminal, and put itself into the background. In addition, all
error messages are logged via syslog(3), instead of via
perror(3). Note that if both the -C and -v options are used in
conjunction with the -b option, any errors that are detected in
the data stream will not be reported.
-c To specify that the data must be checked to verify its accuracy,
use the -c option.
Because this is done by comparing one character at a time, using
the -c option can cause noticeable throughput degradation. The
data is verified by filling up the data buffer with a 32-byte re-
peating pattern of all the lower case letters and the first 6 up-
per case letters of the alphabet. This option is useful for de-
tecting data that has been corrupted. If there is a problem with
lost or duplicated data, this option may generate a large number
of error messages.
-C Similar to -c, except that the data is written out as a sequence
of sequential 64-bit numbers in network byte order.
Because this is done by comparing one word at a time, it is
slightly faster than the -c option, but it can still cause notice-
able throughput degradation. This option is useful for detecting
data that has been lost or duplicated, as it resyncronizes itself
when an error is encountered. However, if the size of the lost or
duplicated data is not an even multiple of 8, it may not resyn-
cronize properly.
-d For TCP, UDP and OSI connections, the -d option turns on the sock-
et-level debugging flag.
-f Indicates that a full-size read must be issued.
Usually, when a read returns a short count, both nettest and
nettestd issue a read for the remaining data for that buffer,
whether or not a short count was received. (The total number of
bytes is not changed.)
-F For TCP connections, the -F option turns on the TCP_NODELAY socket
option. The TCP code in the kernel usually tries to send only
full-sized packets over the network; this is accomplished by de-
laying some writes until a full packet size accumulates. The -F
option disables this algorithm.
-h To turn on hash marks to be printed, use the -h option. Each time
a complete buffer is written or read, a hash mark is printed. If
a read returns a partial count and the -f option is not specified,
a period is printed. If the -f option is specified, a hash mark
is printed each time a read completes, regardless of the amount of
data read.
-m Indicates that for datagram connections -p udp and -p locald) that
nettest should use the sendmsg(2) system call insted of the send-
to(2) system call (see send(2)), and that nettestd should use the
recvmsg(2) system call insted of the recvfrom(2) system call (see
recv(2)), For other protocols this option is ignored.
-n nconns
For TCP, LOCAL and ISO connections, the -n option specifies the
number of simultaneous connections to be opened.
For each connection, a subprocess is created. Each subprocess,
after establishing a connection to the server and negotiating the
options, suspends itself. When all the connections have been es-
tablished, a continue signal is sent to all the subprocesses to
start them running at the same time. As each subprocess com-
pletes, it returns its timing results, and returns that informa-
tion to the main process, which then prints out the individual
timing information. After all the subprocesses have completed,
aggregate timing results given. The aggregate timings are based
on the total amount of data transferred by all the subprocesses,
the start time of the first subprocess to begin writing its data
to its server, and end time of the last subprocess to complete
reading its data from its server. The syncronization information
shows when each subprocess began running, the duration of the data
transfer for each subprocess, and ending time of each subprocess.
These times are relative to the start time of the first subprocess
to began running.
-p protocol
Specifies the protocol in use.
The valid values for protocol are tcp, udp, iso, local, locald,
pipe and file.
If the -p option is not specified, tcp is the default.
The local protocol uses LOCAL domain stream sockets; filename can
be specified to override the default file name nt_socket.
The local protocol uses LOCAL domain datagram sockets; filename
can be specified to override the default file name nt_dsocket.
For pipe protocol connections, two named pipes are created when
you specify filename, one for reading and one for writing. The
nettest program creates the names of these files by appending R
and W to filename. The default names are nt_pipeR and nt_pipeW.
For file protocols, writefile is the name of the special file to
which information is written; readfile is the name of the special
file that is read. The order of writefile and readfile is re-
versed between nettest and nettestd. This allows the same file
names to be specified in the same order for both nettest and
nettestd, because the file to which nettest writes is the file
from which nettestd reads, and vice versa. The intent of this op-
tion is to allow nettest to be run across arbitrary devices that
have a character-device interface that can be accessed just by
opening up a special character file for reading or writing. It is
not intended for for reading or writing to a regular file.
-s n Increases the maximum TCP window by a factor of 2 ^ n; 1 <= n <=
14.
-S tos
For TCP and UDP connections, the -S option can be used to specify
the Type-of-Service (TOS) value for the connection.
A check for the symbolic name tos in /etc/iptos determines the ac-
tual order. (The -t tos option is a valid synonym, for historical
compatibility.)
-V Print out information about the version of the program.
-w Use the MSG_WAITALL flag when calling recv(2). This allows the
kernel to accumulate incoming data so that the read buffer is
filled before returning control to the application. The use of
this option negates the need for the -f option.
host For TCP, UDP and OSI connections, host is the name of the machine
on which the server is running.
If this is omitted or specified as --, the name that gethost-
name(2) returns is used.
count Specifies the number of read or write operations.
A value of -- indicates that the default value must be used. The
default value is 100.
size Specifies the number of bytes to be read or written.
A value of -- indicates that the default value must be used. The
default value is 4096.
port For TCP and UDP connections, specify port to select an alternate
port number.
The port must be a decimal number.
The output from nettest is timing information and a histogram of the var-
ious sizes that the read operations returned. System load affects the
results because all throughput times are calculated from wall-clock
times. The percentages listed for system and user times are percentages
of wall-clock time.
The write time is measured from the time at which the application starts
its first write until the time it completes its last write. The read
time begins when the last write is complete and ends when the last read
is complete. Because the kernel may buffer outgoing data, if everything
on the network is working correctly, it is normal for the write times to
be slightly faster than the read times. This difference in throughput
represents the amount of buffering in the kernel and the network round-
trip time. The read and write time is measured from the time the first
write is started to the time the last read is completed; thus, if the
speed of the network is the same in both directions and both machines
have the same processing power and load, the read and write times are the
most accurate.
The histogram output shows the sizes that the read system calls return.
These may not have any correlation to the size and number of packets that
are actually sent and received over the network. This is especially true
for TCP connections.
FILES
/etc/iptos IP TOS database
nt_socket Default name for stream LOCAL domain sockets
nt_dsocket Default name for datagram LOCAL domain sockets
nt_pipeW Default name for write side of named pipes
nt_pipeR Default name for read side of named pipes
SEE ALSOgethostname(2), recv(2) and send(2)BUGS
The -p pipe, -p local and -p locald options create named pipes and LOCAL
domain sockets, respectively, that remain after the programs exit.
If -p pipe filename is specified and filename is either a relative or ab-
solute path name, neither nettest nor nettestd insert the W and R before
the final component of the path name; they are always prepended to the
entire file name.
BSD/OS November 9, 1992 4
