Re: [LAU] Question about DSP/Processor Load and multiproc support

Perhaps my question is not so-well posed.
Let's turn it like this:

How is the DSP load appearing in jack computed, and how does it have to
deal with CPU/Memory/whateverphysicalthing load?

Does jack generate an xrun as soon as it reaches 100% DSP load as a
"security operation" or is it due to hardware limitation when reaching
100% DSP load?

Thanks.

On Thu, Oct 08, 2009 at 09:25:18AM +0200, Aurelien wrote :
> Hello,
>
> I suppose this question has already been posted, and answered, but I
> can't get any explanation which seems to fit my question, or I do not
> understand it, so I post it there.
>
> I know that Jack DSP Load isn't a true DSP Load, it's nothing but
> buffering, if I'm not wrong.
> Though, I don't know what hardware part of the computer the DSP finally
> relies to (or affects, or whatever), but I suppose it's the processor,
> as the load of the DSP when launching, for example, one AMS seems to be
> the same as the processor load assigned to the AMS process.
> So, the first question is, does the DSP mean "processor load due to
> software appearing in jack"?
>
> Next, question is about multicore. When I monitor my system using top on
> a my quad-core or duo-core machines, I can reach total processor loads
> such as 400% or 200%, as top seems to be designed for monocore.
> Actually, it obviously means 4x100% or 2x100%.
> When I use Jack1, I got an Xrun (at least) every time I reach the 100%
> DSP load, which is finally with quite few softwares (4 AMS, 1
> Sooperlooper, 1 seq24, 1 Tapeutape, some routing, some qmidiroute) for
> my configuration (Intel Q6600 Core 2 Quad, 8Gb RAM, Focusrite Saffire
> Pro 40 soundcard -firewire, with developpment version of FFADO-).
> What I was wondering is: does jack prefer to create an Xrun as soon as
> 100% DSP load is reached?
>
> I just installed jack2, in order to check whether it might increase the
> perf of my system, but, at first sight, the DSP load is the very same as
> with jack1.
>
> OK, here it is, I'm sorry it's not really clearly explained, it's quite
> clear in my head, but unfortunately, with french words!!!
>
> Thanks.
>
> --
> Aurélien
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>

-- 
Aurélien
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