Re: [gull] Contrôle de ntp

[Jacques-André Eberhard]

Bonjour,

Je crois que je vais essayer avec ceci
"
Give the kernel command line option
        clock=pmtmr
      With this option, the kernel corrects more properly for lost ticks,
but occasionally overcorrects and ends up gaining time slowly. This option
is the default for most 2.6 kernels, but some distributions may patch their
kernels to change the default. In SuSE SLES 9 kernels, the default is
clock=tsc. The code enabled by the tsc setting severely overcorrects for
lost ticks when used in a virtual machine and tends to gain time rapidly.
"
 de http://www.vmware.com/support/kb/enduser/std_adp.php?p_faqid=1420

je vous donne le résultat des courses demain...


>Ma conclusion est :
>
>executer ntpdate avant de demarer xntp, puis s'assurer que l'interval 
>mentionne ci-dessous reste a 64 secondes.
>
>dc
>
>POLL INTERVAL CONTROL
> This version of NTP includes an intricate state machine to reduce the
>network 
>load while maintaining a quality of synchronization consistent with the 
>observed jitter and wander. There are a number of ways to tailor the 
>operation in order enhance accuracy by reducing the interval or to reduce 
>network overhead by increasing it. However, the user is advised to
>carefully 
>consider the consequenses of changing the poll adjustment range from the 
>default minimum of 64 s to the default maximum of 1,024 s. The default 
>minimum can be changed with the tinker minpoll command to a value not less
>
>than 16 s. This value is used for all configured associations, unless 
>overriden by the minpoll option on the configuration command. Note that
>most 
>device drivers will not operate properly if the poll interval is less than
>64 
>s and that the broadcast server and manycast client associations will also
>
>use the default, unless overriden. 
> In some cases involving dial up or toll services, it may be useful to 
>increase the minimum interval to a few tens of minutes and maximum interval
>
>to a day or so. Under normal operation conditions, once the clock
>discipline 
>loop has stabilized the interval will be increased in steps from the
>minumum 
>to the maximum. However, this assumes the intrinsic clock frequency error
>is 
>small enough for the discipline loop correct it. The capture range of the 
>loop is 500 PPM at an interval of 64s decreasing by a factor of two for
>each 
>doubling of interval. At a minimum of 1,024 s, for example, the capture
>range 
>is only 31 PPM. If the intrinsic error is greater than this, the drift file
>
>ntp.drift will have to be specially tailored to reduce the residual error 
>below this limit. Once this is done, the drift file is automatically
>updated 
>once per hour and is available to initialize the frequency on subsequent 
>daemon restarts.
>_______________________________________________
>gull mailing list
>gull at lists.alphanet.ch
>http://lists.alphanet.ch/mailman/listinfo/gull
>
>
>
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