[ntp:questions] Re: ntp server error

Richard B. Gilbert rgilbert88 at comcast.net
Mon Jul 31 11:49:46 UTC 2006


Marcus König wrote:
> Hi at all,
> 
> i have a problem with my ntp-server:
> 
> AIX 5.3  ntpd 4.2.2 at 1.1532 Mon Jun 19 14:51:42 UTC 2006 (4)
> Hopf-referenceclock connected to tty0:
>  TTY                                                 tty0
>   TTY type                                            tty
> 
>   TTY interface                                       rs232
>   Description                                         Asynchronous
> Terminal
>   Status                                              Available
> 
>   Location                                            01-S2-00-00
> 
>   Parent adapter                                      sa1
> 
>   PORT number                                        [0]
>                          +
>   Enable LOGIN                                        disable
>                          +
>   BAUD rate                                          [9600]
>                          +
>   PARITY                                             [none]
>                          +
>   BITS per character                                 [8]
>                          +
>   Number of STOP BITS                                [1]
>                          +
>   TIME before advancing to next port setting         [0]
>                          +#
>   TERMINAL type                                      [dumb]
>   FLOW CONTROL to be used                            [ixany]
>                          +
>   OPEN DISCIPLINE to be used                         [dtropen]
>                          +
>   STTY attributes for RUN time
> [hupcl,cread,brkint,icrnl,opost,tab3,onlcr> +
>   STTY attributes for LOGIN
> [hupcl,cread,echoe,cs8]
>   LOGGER name                                        []
>   STATUS of device at BOOT time                      [available]
>                          +
>   REMOTE reboot ENABLE                                no
>                          +
>   STATUS of device at BOOT time                      [available]
>                          +
>   REMOTE reboot ENABLE                                no
>                          +
>   REMOTE reboot STRING                               [#@reb@#]
>   TRANSMIT buffer count                              [16]
>                          +#
>   RECEIVE trigger level                              [3]
>                          +#
>   STREAMS modules to be pushed at OPEN time          [ldterm]
>                          +
>   INPUT map file                                     [none]
>                          +
>   OUTPUT map file                                    [none]
>                          +
>   CODESET map file                                   [sbcs]
>                          +
> 
>   POSIX special control characters:
> 
>   INTERRUPT character                                [^c]
> 
>   QUIT character                                     [^\]
> 
>   ERASE character                                    [^h]
>   KILL character                                     [^u]
>   END OF FILE character                              [^d]
>   END OF LINE character                              [^@]
>   2nd END OF LINE character                          [^?]
>   DELAY SUSPEND PROCESS character                    [^y]
>   SUSPEND PROCESS character                          [^z]
>   LITERAL NEXT character                             [^v]
> 
>   START character                                    [^q]
>   STOP character                                     [^s]
>   WORD ERASE character                               [^w]
>   REPRINT LINE character                             [^r]
>   DISCARD character                                  [^o]
>   Apply change to DATABASE only                       no
>                          +
> 
> errpt-error:
> 
> ---------------------------------------------------------------------------
> LABEL:          TTY_OVERRUN
> IDENTIFIER:     9D30B78E
> 
> Date/Time:       Mon Jul 31 06:58:51 MST 2006
> Sequence Number: 1494
> Machine Id:      0059E4BC4C00
> Node Id:         csnim2
> Class:           S
> Type:            TEMP
> Resource Name:   tty0
> 
> Description
> RECEIVER OVER-RUN ON INPUT
> 
> Failure Causes
> EXCESSIVE LOAD ON PROCESSOR
> 
>         Recommended Actions
>         REDUCE SYSTEM LOAD.
>         REDUCE SERIAL PORT BAUD RATE
> 
> Duplicates
> Number of duplicates
>           25
> Time of first duplicate
> Mon Jul 31 06:58:13 MST 2006
> Time of last duplicate
> Mon Jul 31 06:58:51 MST 2006
> 
> I already changed the parameter FLOW CONTROL without success.
> 
> Do you have an idea, how i can clear these error?
> 
> many thanks.
> 
> regards Marcus König
> 

Unless your error message is written in some sort of a secret code, it's 
telling you plainly both the problem and the solution!

The processor is too busy to pull the characters out of the UART as fast 
as they are arriving.  For many years now, many UARTs have been equipped 
with a sixteen character FIFO buffer.  If your UART is so equipped, that 
says that for something like 16 milliseconds the processor has not read 
a character from the UART.

Reduce the load on the processor!  Check if you have processes running 
at a higher priority than ntpd; ntpd does not place a high load on a 
processor but it needs to process in near real-time.

Or get faster hardware.  It's not likely that this is the solution; your 
hardware would have to be VERY slow to cause this problem.  OTOH if you 
processor is using PIO to access a disk rather than DMA, that could do it.




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