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vForce Performance
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vForce Performance


  • Subject: vForce Performance
  • From: dct <email@hidden>
  • Date: Mon, 23 Jan 2012 12:24:16 -0800

I recently posted a query on the Xcode-Users list but with no reply so far.

I hopes of accelerating some standard C functions, I've run a few timing experiments to assess vForce.h function performance.  The results are disappointing.

 - Comparing the time to run vvsqrt( ) on a 10000 point data file to a simple for( ) loop,
   i.e., for( ii=0; ii<10000; ii++ ) yy[ii] = sqrt[ii] , shows a very slight improvement
    ( ~23 nsec per input data pt. for vvsqrt vice ~24 nsec for the loop),
 - Comparing the time to run vvsin( ) in similar fashion actually shows the loop to be better--
     ( ~39 nsec per data pt. for vvsin vice ~21 nsec for the loop).

(FYI,  tests were run under Xcode 3.2.3 on a MacPro w Dual-Core, 3 GHz Xeon processor.)

My questions are:
  - Are these timing results consistent with expected vForce performance?
 - If not, what does one need to do to get the expected performance?
 - And, regardless, are there other considerations that would favor use of the vForce functions?

Don Thompson
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