[LAU] optimizing jackd build

[Mike Taht]

On 4/9/07, Ken Restivo <ken at restivo.org> wrote:
>
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> On Mon, Apr 09, 2007 at 08:18:10AM -0700, Mike Taht wrote:
> > At present the major bottlenecks left for ardour and jack are very much
> down
> > in the noise floor.  A typical user now spends more cpu time in plugins
> than
> > in those two core programs. (thus I've been oprofiling a few plugins
> > heavily, among other things, now have a SSE'd comb_run routine... and
> > hopefully will announce some sped up plugins soon)
> >
>
> That would be a HUGE help for me.
>
> Hint hint: the CAPS and TAP plugins would be especially nice to have
> optimized.
>
> (Yes, I tried compiling them with SSE enabled, using GCC 4.1, and
> experienced *higher* CPU usage that way.)


Well, I have a great deal of hope for truly SSEing many of the plugins. In
particular, if it were possible to stop using the "Flush_to_zero" macro and
just turn on SSE's builtin support for flushing denormals to zero for
plugins that care might be a big win - but that may have audible effects
elsewhere.

As for comb_run - which accounts for a large precentage of tap_reverb's
runtime, for example - SSEing it cuts the number of ops by a lot, but as it
has poor locality of reference so it may not actually SSE well. My current
test case is the parametric EQ which spends a lot of time there, but also
has some gnarly setup....

only answer is to try it and benchmark... may have some results by the end
of the month.


- -ken
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-- 
Mike Taht
PostCards From the Bleeding Edge
http://the-edge.blogspot.com
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