[Xenomai-help] Xenomai User Space: Using 100% CPU power

[Xenomai-help] Xenomai User Space: Using 100% CPU power

[M. Koehrer]

Hi everybody,

I have an application where I need extreme precise timing (about 1µs) for a couple of seconds
using a standard PC (to access a I/O PCI board).
For this, I want to write an application that initializes normally and 
whenever the software is in a certain state, I want to enter a  "high-precision-timing mode".
In this high-precision-timing mode, I want to disable all interrupts and poll permanently on a PCI I/O board.
The timing itself can be directly taken from the CPU's TSC using rdtsc.
Within this mode, the time measurement of register changes on the PCI I/O board is very important.
After a couple of seconds, when all relevant data is taken, I want to leave this
"high-precision-mode" and come back to the normal mode.
Then the measurement results are interpreted in detail.
All this should happen in user mode, not in kernel mode.

My questions are now: 
Is this possible using Xenomai?
How can I enter a mode that disables all interrupts (including timer) for a while?

Thanks for any help on this!

Regards

Mathias




-- 
Mathias Koehrer
mathias_koehrer@domain.hid


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Re: [Xenomai-help] Xenomai User Space: Using 100% CPU power

[Jan Kiszka]

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M. Koehrer wrote:
> Hi everybody,
> 
> I have an application where I need extreme precise timing (about 1µs) for a couple of seconds
> using a standard PC (to access a I/O PCI board).
> For this, I want to write an application that initializes normally and 
> whenever the software is in a certain state, I want to enter a  "high-precision-timing mode".
> In this high-precision-timing mode, I want to disable all interrupts and poll permanently on a PCI I/O board.
> The timing itself can be directly taken from the CPU's TSC using rdtsc.
> Within this mode, the time measurement of register changes on the PCI I/O board is very important.
> After a couple of seconds, when all relevant data is taken, I want to leave this
> "high-precision-mode" and come back to the normal mode.
> Then the measurement results are interpreted in detail.
> All this should happen in user mode, not in kernel mode.
> 
> My questions are now: 
> Is this possible using Xenomai?
> How can I enter a mode that disables all interrupts (including timer) for a while?

We had this discussion recently here, see

https://mail.gna.org/public/xenomai-help/2006-10/msg00172.html

And be aware that you are about to toast Linux's time keeping (but I
guess that of lower priority in this scenario).

Jan


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