Timed loop and CPU usage

Platform is WIN_XP Pro and machine is a P4 at 2.5Ghz with 512 Mb ram.
LV7.1 + PCI 6229
I am using 50ms Timed loop for running a state machine inside it
and also a whole lot of other things like reading / writing
DAQMx functions; file I/O functions and such. As the
project involves a main and sub-panlel set up local variables
could not be elimnated fully and there should be something like 150 of
them. But not all are accessed always - maybe about 15 of them at any
given time depending on the SM staus.
Problem :
Once started the "Finished late" indication is off and
the actual timing alternates between 49 to 52 ms. The CPU
usage is around 25%.
But as time goes by, the system gets unstable : After 15 minutes
or so, the Finished Late indication is always ON and the CPU usage is
gradually tending towards or exceeds 100%.
Obviously the machine control timing now gets affected and things slow
down badly. Closing the application ands restarting repeats the above
cycle.
I am at a loss to understand what is happening ? WIll
breaking down the single Timed Loop to multiple ones help ? WIll
that be an efficient way of parallel threading ?
I can post the code but its quite large and will do it as a last resort.
thanks
Raghunathan
Raghunathan
LV2012 to Automate Hydraulic Test rigs.

Hello,
It sounds like an interesting problem. It would be worth some experimentation to figure out what's going wrong - attempting to decouple major "pieces" of the code would be helpful. For example, you could try breaking your code into multiple loops if that makes sense in your architecture, but perhaps you could even eliminate all but one of the loops to begin with, and see if you can correlate the problem to the code in just one of your loops.
Another concern is that you mention using many local variables. Variable read operations cause new buffer allocations, so if you're passing arrays around that way, you could be hitting a problem of forcing your machine to perform many allocations and deallocations of memory. As arrays grow, this can be a bigger and bigger problem. You can use other techniques for passing data around your block diagram, such as dataflow if possible (just simple wires), or queues where dataflow can't dicatate program flow completely.
Hopefully looking into your code with the above considerations will lead you in the right direction. In your case, removing code so that you can identify which elements are causing the problem should help significantly.
Best Regards,
JLS
Best,
JLS
Sixclear

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Could you tell me how to check the memory and cpu usage on NPU?
I think ASR1000 has this command (show platform hardware qfp active...) , but I coudn't find the same command on ASR9001.
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Pause the game when u alt-tab away ^_^
Thats what most native fullscreen games do (the
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hang your whole system.
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yourself at least 20MS per iteration.
ie:
InputStream inputStream;
while(working)
Object waitObject = new Object();
int readCount = 0;
int availableBytes = 0;
int totalBytes = 10;
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threads to have them; THread.sleep() does not.
The 100% CPU issue is especially bad under NT BTW.
If you do this not only will your CPU usage go to negligible, but you
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(T)

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NI DAQmx 8.3 and CPU usage

I have similar problem as described on page http://forums.ni.com/ni/board/message?board.id=250&message.id=23831
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first of all, about system
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Message Edited by davodavo on 04-25-2009 07:55 AM
Message Edited by davodavo on 04-25-2009 07:57 AM

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Message Edited by davodavo on 04-28-2009 12:52 PM
Message Edited by davodavo on 04-28-2009 04:25 PM

Timed loop and CPU usage

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