Re: Latency problem

[Carsten Emde <Carsten.Emde@osadl.org>]

Raphaël,

> [..]
>> root@USBnux:/home/xaf/RT/rt-tests# ./hwlatdetect --threshold=1 --report=/home/xaf/hwlat_report
>> hwlatdetect:  test duration 120 seconds
>>    parameters:
>>         Latency threshold: 1us
>>
>>         Sample window:     1000000us
>>         Sample width:      500000us
>>      Non-sampling period:  500000us
>>         Output File:       /home/xaf/hwlat_report
>> Starting test
>> test finished
>> Max Latency: 38136us
>> Samples recorded: 45
>> Samples exceeding threshold: 45
>> sample data written to /home/xaf/hwlat_report
>
> and the content of the hwlat_report file :
>
>> 1319575592.0802426354	19061
>> 1319575707.0402420761	19036
> [..]
> I really have no idea from where the problem could be. And I need your
> lights to help me.
The hwlatdetect application detects system management interrupts (SMIs). 
Such interrupts are installed by the BIOS and are used to manage various 
things such as battery management, overheat protection and emulation of 
legacy devices (e.g. IDE, PS/2 etc.). You may try to check your BIOS 
settings and disable all these or similar features. Then run hwlatdetect 
again. If it still reports SMIs, the next thing to do depends on the 
promises that you got when you bought the board:

1. It was advertised as an industrial PC to be used in a control systems 
and to run a real-time operating system:
Return the board to the manufacturer along with the printed output of 
hwlatdetect and ask for a fix or your money back.

2. It is a standard server PC board without any promises as to its 
suitability in a real-time system:
There probably is nothing you can do. Try to send the output of 
hwlatdetect to the BIOS manufacturer and nicely ask for a fixed BIOS, 
but I am not very optimistic that you will get one.

Hope this helps,
	-Carsten.
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