SYNCSTAT(8) Maintenance Commands and Procedures SYNCSTAT(8)

NAME

syncstat - report driver statistics from a synchronous serial link

SYNOPSIS

/usr/sbin/syncstat [-c] device [interval]

DESCRIPTION

The syncstat command reports the event statistics maintained by a
synchronous serial device driver. The report may be a single snapshot
of the accumulated totals, or a series of samples showing incremental
changes. Prior to these it prints the device name being used to query
a particular device driver, along with a number indicating the
channel number (ppa) under control of that driver.


Event statistics are maintained by a driver for each physical channel
that it supports. They are initialized to zero at the time the driver
module is loaded into the system, which may be either at boot time or
when one of the driver's entry points is first called.


The device argument is the name of the serial device as it appears
in the /dev directory. For example, zsh0 specifies the first on-
board serial device.


The following is a breakdown of syncstat output:


speed The line speed the device has been set
to operate at. It is the user's
responsibility to make this value
correspond to the modem clocking speed
when clocking is provided by the
modem.
ipkts The total number of input packets.
opkts The total number of output packets.
undrun The number of transmitter underrun
errors.
ovrrun The number of receiver overrun errors.
abort The number of aborted received frames.
crc The number of received frames with CRC
errors.
isize The average size (in bytes) of input
packets.
osize The average size (in bytes) of output
packets.

OPTIONS

-c
Clear the accumulated statistics for the device
specified. This may be useful when it is not desirable to
unload a particular driver, or when the driver is not
capable of being unloaded.


interval
syncstat samples the statistics every interval seconds
and reports incremental changes. The output reports line
utilization for input and output in place of average
packet sizes. These are the relationships between bytes
transferred and the baud rate, expressed as percentages.
The loop repeats indefinitely, with a column heading
printed every twenty lines for convenience.

EXAMPLES

Example 1: Sample output from the syncstat command:

example# syncstat zsh0


speed ipkts opkts undrun ovrrun abort crc isize osize
9600 15716 17121 0 0 1 3 98 89


example# syncstat -c zsh0

speed ipkts opkts undrun ovrrun abort crc isize osize
9600 0 0 0 0 0 0 0 0


In the following sample output a new line of output is generated
every five seconds:


example# syncstat zsh0 5

ipkts opkts undrun ovrrun abort crc iutil outil
12 10 0 0 0 0 5% 4%
22 60 0 0 0 0 3% 90%
36 14 0 0 0 1 51% 2%

SEE ALSO

attributes(7), syncinit(8), syncloop(8)

DIAGNOSTICS

bad interval: arg

The argument arg is expected to be an interval and could not be
understood.


device missing minor device number

The name device does not end in a decimal number that can be
used as a minor device number.


baud rate not set

The interval option is being used and the baud rate on the
device is zero. This would cause a divide-by-zero error when
computing the line utilization statistics.

WARNINGS

Underrun, overrun, frame-abort, and CRC errors have a variety of
causes. Communication protocols are typically able to handle such
errors and initiate recovery of the transmission in which the error
occurred. Small numbers of such errors are not a significant problem
for most protocols. However, because the overhead involved in
recovering from a link error can be much greater than that of normal
operation, high error rates can greatly degrade overall link
throughput. High error rates are often caused by problems in the link
hardware, such as cables, connectors, interface electronics or
telephone lines. They may also be related to excessive load on the
link or the supporting system.


The percentages for input and output line utilization reported when
using the interval option may occasionally be reported as slightly
greater than 100% because of inexact sampling times and differences
in the accuracy between the system clock and the modem clock. If the
percentage of use greatly exceeds 100%, or never exceeds 50%, then
the baud rate set for the device probably does not reflect the speed
of the modem.

March 6, 2023 SYNCSTAT(8)