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gradual performance degradation of clEnqueueReadImage()

Question asked by laoshi on Apr 28, 2012
Latest reply on Apr 29, 2012 by laoshi

Hello,

 

I'm doing a Ray Cast of some fairly large volume (examples from http://www.volvis.org) for medical applications.

 

I'm generating a "DRR", that is, a digital X-Ray of the objects by integrating along a ray.

 

I have a 1024 by 1024 by 16 bit intensity destination image.

 

I am rotating about the volume from 0 - 90 or 180 degrees.

 

I notice, both in my own timings and in the AMD profiler that the read of the 2D projected image is slowing down over time:

 

For instance

elapsed time = 363.08

elapsed time = 359.41

elapsed time = 353.417

elapsed time = 359

elapsed time = 365.704

elapsed time = 364.322

elapsed time = 364.974

elapsed time = 364.162

elapsed time = 360.681

elapsed time = 358.457

elapsed time = 366.828

elapsed time = 366.772

elapsed time = 369.182

elapsed time = 365.62

elapsed time = 371.733

elapsed time = 373.001

elapsed time = 373.148

elapsed time = 373.764

elapsed time = 376.527

elapsed time = 378.569

elapsed time = 379.176

elapsed time = 380.202

elapsed time = 383.006

elapsed time = 384.96

elapsed time = 385.866

elapsed time = 387.969

elapsed time = 386.392

elapsed time = 386.947

elapsed time = 395.193

elapsed time = 398.699

elapsed time = 400.417

elapsed time = 403.66

elapsed time = 406.639

elapsed time = 410.729

elapsed time = 414.783

elapsed time = 417.085

elapsed time = 420.945

elapsed time = 424.348

elapsed time = 430.082

elapsed time = 434.506

elapsed time = 438.68

elapsed time = 445.329

elapsed time = 441.212

elapsed time = 446.529

 

And this get's much slower as time goes on.

 

I don't see any "hints" from the profiler as to what may be the problem. Has anyone seen this type of problem, and what the cause might be?

 

Thanks,

 

Rick

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