[vtkusers] threads and vtkSynchronizedTemplates

[Lisa Avila]

I just did a test with my dual processor Pentium IV Xeon 1.7 GHz system. 
With TestSynchronizedTemplates3D.tcl with 1 processor an update took about 
.151 seconds, and with 2 processors it took about .11 seconds.  (wall time 
with tcl)

What method are you using from TimerLog? If you are using CPU time - keep 
in mind that it will ALWAYS take longer when using more processors - 
otherwise you would have better than linear speedup! The CPU time adds up 
the time of all threads (except on Windows where it simply reports wall time).

Lisa



At 10:32 AM 4/15/2002, Dave Semeraro wrote:

>Hello there,
>
>I am using vtkSynchronizedTemplates3D to generate isosurface geometry from a
>structured points data set. I am running the test on a dual 1.4ghz athlon 
>processor linux system
>running the 2.4.18-xfs kernel. I am timing the results using the 
>vtkTimerLog class. It seems to
>make little difference in time whether I use 1 or 2 threads to do the 
>test. In fact the 2 thread
>case seems to run slightly slower. The isosurface value I choose generates 
>over 800,000
>polygons and takes about 0.8 seconds to complete so I dont think it is a 
>timer resolution
>problem. I have verified that setting the number of threads does indeed 
>cause both cpus to
>be used ( verified via top output).  I must be doing something wrong. Why 
>bother with threading
>if you see no difference in speed? Has anyone else seen similar results? 
>Can anyone explain
>what I am doing wrong?
>
>Best Regards,
>Dave Semeraro
>
>Dave Semeraro Ph.D.
>Visualization and Virtual Environments Group
>NCSA University of Illinois
>605 E. Springfield Ave.
>Champaign, IL 61820
>Semeraro at ncsa.uiuc.edu
>(217) 244-1852
>
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