[asterisk-dev] nVidia Cuda

[Matthew Rubenstein]

	Do you know the relative MIPS consumed by G.729 in each of the decoding
and the transformation phases? If the decoding is a significant
percentage, then it will block the CPU process while the GPU waits a
long time. While a really fast GPU can afford to waste cycles in
inefficient logic if it's still faster than the CPU.


On Mon, 2007-03-05 at 09:13 +0100, CA DM wrote:
> You don't need to port the entire codec code to a GPU. GPU aren't 
> good general purpose processors, such as CPU aren't good stream processors.
> 
> Code need to be cleaverly distributed across the specific abilities 
> of CPU and GPU (eg.: decoding and unpacking the data stream is a task 
> suited for the CPU, like data block transformations are for the GPU) 
> if you want to get the most from both.
> 
> At 20.38 04/03/2007, you wrote:
> >         Compression algorithms have generally not been ported to 
> > GPUs like the
> >G80. They're usually more logic and branch oriented than just brute
> >force multiply-accumulates that GPUs specialize in. I also haven't seen
> >any of the popular Asterisk codecs, like G.729 or GSM, ported to any
> >GPU. Is there a source for codecs ported to GPUs? Or any research
> >showing a good approach?
> >
> >
> >On Sun, 2007-03-04 at 10:12 -0700, asterisk-dev-request at lists.digium.com
> >wrote:
> > > Date: Sat, 03 Mar 2007 22:05:19 -0500
> > > From: Wai Wu <wkwu at calltrol.com>
> > > Subject: [asterisk-dev] nVidia Cuda
> > > To: asterisk-dev at lists.digium.com
> > > Message-ID: <B0430B20D208514CB2AFF57E81645C3101B970 at k3-1.Calltrol.com>
> > > Content-Type: text/plain; charset="iso-8859-1"
> > >
> > > Hi devs,
> > >
> > > Has any one looked into cuda to see if cpu intensive part of
> > > asterisk(like codecs and conference) can be moved to the G80
> > > processor? I found that the GF8800 cards are very inexpensive (around
> > > 400 USDs per). I have ported some of our financial applications to
> > > this board and found almost 10x performance improvement over the 3GHz
> > > C2D host processor. I would like to do the same for asterisk.
> > >
> > > To start. I have been looking into the asterisk code and have no crew
> > > how it is structured except the addon applications. Here I have two
> > > questions.
> > >
> > > 1) Is each channel use their own thread if a codec is used?
> > > 2) Which part of the asterisk code actually makes the call to the
> > > necessary codec? I notice in the applications. They save and set the
> > > frame format, then read from the channel. So I trace the read
> > > function, but all it does is reading from a file descriptor. So I need
> > > some help here.
> >--
> >
> >(C) Matthew Rubenstein
> >
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-- 

(C) Matthew Rubenstein