Multi-core threaded program pauses

[SDR Kid]

I tried to exercise two of my quad cores using timed loops, but when I set the times down to 10 and 20 msec then the display pauses and LabView becomes non-responsive.  I have a DELL Precision 7500, so these are Intel processors.  Is the graphics causing the program to pause or something else?

[RavensFan]

I see no problems with it running on my HP with quad core AMD CPU.  That included setting the loop rate all the way down to 0 ms.

Message Edited by Ravens Fan on 08-01-2009 01:24 AM

[BillMe]

No problem here running on my i7 quad-core under Vista64.

Message Edited by Bill@NGC on 07-31-2009 11:06 PM

[SDR Kid]

The Dell is an Intel based machine, so that may not be a good comparison but it's good to know there's no problems with AMD cores.  My organization will not approve use of Vista, so I have to use XP until they move on.  I have XP 32 bit loaded because of some driver issues with the PCI-5640R.  I only have 4GB RAM because of the 32bit OS.  I wonder if the 32bit configuration is causing problems? 

[RavensFan]

My previous test was on home premium vista 64 bit.  I tried your VI here at work on HP with 2 cores Intel with XP.  I do see the pauses here.  Windows task manager pauses as well and shows a spike in CPU usage when it comes back.

[SDR Kid]

As an experiment, I converted the timed loops to standard while ones.  The application ran much faster with no pauses.  Task Manager showed spikes on cores 3 and 7.  I increased the number of while loops to 5 and hit 32% processor capacity, but Task Manager showed the majority of the load still be carried by 3 and 7 but the others were starting to come up.  I wonder how NI implemented the timed loop because apparently it cannot lock down a core, but rather goes to Windows and requests run each iteration of a loop as a single thread.  The pauses could be caused by waiting for system interrupts, but that doesn't explain why it effects the other Windows applications like Task Manager.