[ardour-dev] sse optimizations

John Rigg ardev at sound-man.co.uk
Sat Jan 28 17:50:38 PST 2006


On Thu, Jan 19, 2006 at 06:47:24PM +0200, Sampo Savolainen wrote:
> btw. You might be aware of this already, but the optimized assembler
> code is available only for 32 bit x86 platforms. We have the functions
> for x86/64 somewhat ready (or are they completely ready Mr. Rigg?), but
> we will have to wait until 2.0 matures a bit before we start adding
> them.

I've finally had time to test the x86_64 SSE optimizations in Ardour. They
work. I've only done a few quick tests so far:

Mix 6 x 44.1 kHz tracks:
With SSE optimizations average dsp load is 2.3%
Without SSE optimizations dsp load is 3.1%

Mix 12 x 44.1 kHz tracks:
With SSE optimizations average dsp load is 3.0%
Without SSE optimizations average dsp load is 4.5%

Mix 20 x 44.1 kHz tracks:
With SSE optimizations average dsp load is 4.6%
Without SSE optimizations average dsp load is 6.5%

The  reduction in CPU load isn't quite as dramatic as on x86 32-bit
(not too surprising as the x86_64 ABI makes greater use of CPU registers).
I'll put together a patch in the next day or two so others can try it.

John



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