[Ardour-Dev] Hello, some tech talk, etc.
Gabriel M. Beddingfield
gabriel at teuton.org
Sat Jul 7 12:01:00 PDT 2012
On 07/07/2012 06:15 AM, Fons Adriaensen wrote:
> Most time seems to go into the float to integer
> conversion that is part of _sincos->ind(). There
> is no way to avoid that, except by replacing the
> sine/cosine lookup tables by real calls to sinf()
> and cosf(), but that's even worse.
Based on past experience, I would bet the the problem is *not* the
float-to-int conversion but a memory access problem (cache miss). I.e.
when you access some data, it causes the CPU to refresh its cache. In
C++, it's easy to hit this problem by accessing a member variable of
your class (pointer-to-pointer-to-data).
Can you post a disassembly+source ? Did you compile for 32-bit or
64-bit? (gcc's 64-bit optimiser is scads better than the 32-bit one.
E.g. the 64-bit optimiser will easily vectorize loops that the 32-bit
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