[nmglug] odd IO-Wait conditions

[Aaron Birenboim]

I am working on a scientific computing problem (using the GPU -- OpenGL)
where when I try to do my test runs, I get into a state where any
graphics response of my computer comes nearly to a halt,
the machine becomes sluggish, and it spends most of it's time
reporting a "wait" state.

I cannot reproduce this behavior while stepping through in
a debugger.  It only happens several seconds into
a longer full-speed run.

This test routine is dumping many tens (perhaps hundreds)
of MB of disk writes per second.  Scores of files,
each of size 1 to 8 MB.

How can I find out what is causing this near lock-up?
How can I avoid it?

Is this kind of thing often seen with many mid
sized files being generated?
Could it be ab OpenGL thing, where something is not
cleanly flushed, and the GPU is doing something odd?

(I am writing to floating point FBO's, and retrieving
   results with glReadPixels())

Thanks for any advice:

          aaron