Re: [Discuss-gnuradio] FX2 firmware

[Dominik Auras]

Hi!

> Hmmm.  My application is RX-only.   Using 8-bit samples, that 45Mb/s
> gives about 20Msps.    I have a QX9770 system running
>   at 3.7GHz, but *still* get overruns at two channels, 8Msps per
> (complex) channel.  I also get overruns at 16Msps, single-channel.
You mean, your system doesn't even sustain 32 Mb/s?

> At 8Msps dual-channel, my application (an all-mode radio astronomy
> receiver system) burns up about 2.75CPU on the above-mentioned
>   address@hidden (with slower memory that will get upgraded soon!).   I
> get overruns a couple of times per minute with this
>   setup.
Could be a problem of your CPU, too. In our lab, our eightcore machine 
has overruns, while my notebook with a core 2 duo does not. I have 
figured out that this is because of multiprocessor communication, the 
eight cores are composed of two quadcore processors, which are themself 
two dualcores on one die. Restricting the scheduler (taskset 0x11 app) 
to two cores which reside in the same dual core, it was fine, no 
overrun. Adding one core, whatever location, and there were overruns.
However, before noticing this fact, I had already turned down cpu usage 
of that specific app (the transmitter) down to two cores by aggressive 
optimization.

> What type of system are you getting reliable 45Mb/s receive throughput
> on, and how complicated is your signal processing
>   flowgraph?
C2D E6750, 4 Gb RAM, ICH9 USB Controller
I am using test_usrp_standard_rx, no signal processing.

Dominik