IPP vector length is very important...

IPP vector length is very important...

I guess I know why I had trouble with some IPPs. It's the length!!! Be very carefull with it!
For example ippsDotProd function is faster only ifvector length is higher than ~30 (on my Pentium 4)! The longer the vector the more speed gain you have... see the graph below.

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What data typeof ippsDotProd functionin your test? Which version of IPP are you using? If you think the performance is impacted bythe length of vector in ippsDotProd functions, please submit an issue to Intel Premier Support, aslo it would be helpful if you can supply a small test case that can reproduce the problem.

Ying Song
Intel IPP