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On Mon, Jul 25, 2011 at 5:04 AM, Maurizio De Cecco  wrote:

quoted text
> Short resume of my initial post: i found that using the gcc vector

> extensions induced a 2x slow down using gcc, and a 4x speed up in clang.

[snip]

quoted text
>

> I include the code, results and scripts to run the tests in a small zip

> if anybody want to make other tests; the test code compute an arbitrary

> vector computation (essentially 100 million multiply add), starting from a

> seed given as argument.

I'm getting SIMD instructions when I compile.  However, you have two

things slowing you down:
  - The calculations for the for(;;) loop is slowing you down with

every iteration.

  - You're only using one xmm register, so you're getting some memory slowdowns.
Both of these can be solved by having gcc unroll your loops for you

(recompile with -funroll-loops).
In addition, you're handling 3 buffers at a time.  bufc[k] = bufa[k] *

bufb[k].  You might be able to speed it up a little by converting the

code to:
    memcopy(bufc, bufa, N*sizeof(float));

    for(k=0; kLinux-audio-dev@lists.linuxaudio.org

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