Re: [Discuss-gnuradio] sustainable gnuradio MFLOPS for streaming processing

[LD Zhang]

Hi, Please my comment below:

You can probably get a rough estimate of the lower limit of your processors
ability to do something like an FIR filter with some simple
calculations:
A 10-point FIR filter needs to do 10 multiplies and 9 additions.
Blissfully ignoring branching that's 19 instructions for each output.
So let's say we've got a simple FIR filter that outputs the same sample rate
as it inputs.

Using the table in here:
http://en.wikipedia.org/wiki/Instructions_per_second it looks like modern
CPUs clocked around 1GHz should expect between 2-5 IPS / (1/clock speed).
Pick your favorite (I'm guessing you're on older hardware so let's go with
2). 2 * 1GHz = 2000 MIPs. So you can process 1M samples through a very
poorly implemented 10-tap FIR filter. That in itself is also a pretty poor
estimate. I see Marcus just replied as well and as he said, the best way to
*know* is just to try it out on your hardware; there's no substitute for
that.


>>> I am confused: 10-tap FIR according to the above is 19 IPs, so 1M
samples correspond to 19 MIPS, much below the 2000 MIPS limit?
Am I missing something?

LD