[sdiy] DSP on GPU?

[ASSI]

On Friday 11 March 2011, karl dalen wrote:
> What happened to all the ideas about running DSP code on GPU's
> that was hot some years ago, Nivida or something i recall?

It is still non-trivial to use a GPU for audio.  One problem is to find 
enough parallelism while keeping the memory access pattern in line with the 
GPU architecture (get this part wrong and the penalty is a three orders of 
magnitude or worse slowdown) and another one is getting the data back out 
the GPU (the fastest way out actually is through the HDMI, but that comes 
with its own problems).  Latency is a problem, especially if some data goes 
the "wrong" direction (i.e. back to the CPU).  Last but not least, none of 
the articles talks about efficiency - the GPU that have general enough 
programming facilities are very power hungry and the low-power GPU that 
exist today are not very programmable for things other than graphics.

Just in, some experiments on the most general GPU architecture avilable 
today (Nvidia Fermi, on a GTX480):

http://www.aes.org/journal/online/JAES_V59/1_2/

"As a result we conclude that GPUs are well suited for
audio applications that need heavy computation, can be
parallelized, and can tolerate some latency. It is essential
to get enough concurrent threads running so that the GPU
is fully utilized. In practice this often means increased
buffer sizes and thus increased latencies. However, in
many practical cases this cost is acceptable, since the
latency is only a few milliseconds. Now that it is possible
to use GPU hardware to do audio signal processing, more
real-time performance is available than ever before."


HTH,
Achim.
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