On Fri, Nov 05, 1999 at 04:10:36PM +0000, Bernd Blessmann wrote:
> Hello,
>
> I've problems with the measurement example
> (rtl/examples/measurements/rt_process.o). I am using rtl version 2.0.
>
> When I am trying to run the module with peridoc_mode=1 both, the minimal
> and maximal error times are getting higher and higher the longer the
> task is running. Below is an example output.
The measurement is showing that the tsc clock (cycle timer) and the
worthless 8253 timer are drifting apart. On oneshot, we resynchronize
at every interrupt, but in periodic mode we do not. In practice
this problem is generally not serious: the timer does generate a
good periodic interrupt, it is just that it does not track the
cycle timer.
>
> The oneshot_mode works fine. Can anybody explain what the differnces
> between these two clock modes are and when to use which mode?
> Where can I find information about the clocks (and there modes) used for
> scheduling?
>
>
> BTW: The readme file for this example says
> "Parameters:
> period: period in milliseconds; default = 1000000"
>
> The period is in nanosecs, or am I wrong?
>
>
> Thanks in advance
> Bernd
>
>
> The output:
>
> #> insmod rt_process.o periodic_mode=1
> #> ./monitor
> min: 3124, max: 9198
> min: 3218, max: 8633
> min: 3295, max: 7560
> min: 3374, max: 4434
> min: 3467, max: 9121
>
> ........... some times later
>
> min: 3800, max: 4896
> min: 3885, max: 4936
> min: 3967, max: 5052
> min: 4051, max: 8668
> min: 4132, max: 8567
> min: 4217, max: 10286
> min: 4297, max: 13908
> min: 4382, max: 7330
>
> ........... some times later
>
> min: 28501, max: 31330
> min: 28586, max: 32025
> min: 28668, max: 32250
> min: 28753, max: 32343
> min: 28842, max: 31666
> min: 28919, max: 32949
> min: 29004, max: 31818
> min: 29092, max: 32755
> min: 29173, max: 35026
> min: 29255, max: 33992
>
> ........... some times later
>
> min: 68454, max: 71993
> min: 68532, max: 75644
> min: 68617, max: 72502
> min: 68703, max: 72290
> min: 68784, max: 71790
> min: 68870, max: 71770
> min: 68953, max: 71846
> min: 69037, max: 71986
> min: 69125, max: 72062
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