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 er rors. abort The number of aborted received fra mes. 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.
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
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%
In this final example a new line of output is generated every five seconds.
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.
Created by unroff & hp-tools. © by Hans-Peter Bischof. All Rights Reserved (1997).
Last modified 21/April/97