[Speex-dev] Performance and Optimization

[Jean-Marc Valin]

Quoting Greger Burman <greger at mobile-robotics.com>:

> The reasons I have posted these questions are: 1) To find out if Speex can
> take advantage of SIMD extensions.

If you define _USE_SSE, CELT is already able to use SSE instructions. You must
be careful on Windows though because it doesn't support C99 var-arrays and
alloca() isn't properly aligned for SSE, so you have to make sure that alloca()
isn't used.

> 2) To maybe learn from someone with previous experience in optimizing Speex
> for moderns x86 architectures before I set off trying all kinds of things on
> my own.

Can't think of anything else you need to know.

   Jean-Marc

>
> See answers inline:
> 2009/6/15 Tom Grandgent <tom at grandgent.com>
>
> > Why haven't you tried using release build with compiler optimizations?
>
> I just haven't started with optimizing... yet.
>
>
> >
> > It's quite possible that the performance picture could be substantially
> > different.  You might end up wasting a lot of time if you do much
> > performance analysis or optimization on a debug build.
>
> Yes, you are right and that is not what I'm doing.
>
>
> > Debug build
> > not only has no optimization - it also has extra checks that may have a
> > significant performance impact depending on the code.
>
> Possibly, but I have identified the most expensive functions. They are all
> from the Speex dll. I believe these will remain the most interesting ones
> also in release build with some O-flags.
> Someone who is knowledgeable in these functions might know if their impact
> can be reduced and what the best practices are.
>
> >
> >
> > If you want to profile with symbols, you know you can compile a release
> > build with symbols, right?  The CodeAnalyst documentation describes
> > how to do that with Visual Studio.  (I've done it.)
>
> Ok. thx.
>
> >
> >
> > Tom
> >
> > Greger Burman <greger at mobile-robotics.com> wrote:
> > >
> > > I have a question about the overall performance of Speex and what I can
> > do
> > > to improve it. I'm running Speex Windows x86, Visual C++ EE compiler. I
> > will
> > > say right away that I've only compiled debug so far and used no compiler
> > > optimizations at all.
> > > I use the uwb-mode, preprocessing, denoising and echo cancellation.
> > > I've noticed that speex consumes a lot of cpu resources. When I run this
> > on
> > > a Celeron 2,6GHz I have to disable EC in order to not overload the cpu.
> > Am I
> > > correct to assume that there are massive floating point calculations
> > > happening?
> > > I did a quick profile with CodeAnalyst and identified the most expensive
> > > functions as (in order):
> > > CPU Clocks, Function
> > > 4657, kiss_fft_stride
> > > 4456, speex_echo_cancellation
> > > 2494, split_cb_search_shape_sign
> > > 1490, fir_mem16
> > > 1419, speex_preprocess_run
> > > I'm looking for advise on how to boost the performance with as little
> > code
> > > rewrite as possible. The architecture for release build will be SSE/SSE2
> > > capable.
> > > 1) Compiler optimizations: Recommended options?
> > > 2) SIMD. Is Speex written to take advantage of SIMD architectures? What
> > must
> > > I do to take advantage of this?
> > > --
> > > Greger Burman
> >
> >
>