On Mon, Jul 27, 2009 at 1:10 PM, Jason Uher
<jasonuher@xxxxxxxxx> wrote:
> Now, the funny thing is that when I run test_usrp_standard_rx in
> /usrp/host/apps using sudo ./test_usrp_standard_rx -D 8 -M 900, I get
> noverruns=0. So with my PC and USRP I can actually get a transfer
> rate of 32MB/s which leads me to believe that something in the setup
> of my application might cause the problems with the USB transfer rate.
>
> Does anyone have any ideas to what might be happening?
>
I've run into similar issues and it probably has more to do with your
hard drive than your processor. test_usrp_standard_rx only tests the
usrp(usb) transfer rates, your flow graph probably chokes at the disk
writes.
A simple way to test this is to have the samples go to a null sink, if
you have no problems, then it's your disk. You can test the speed
capabilities of your disk by setting up a signal source (or two, in
your case) of a specified rate and writing it to disk until you find a
good rate that you can sustain (hdparm will give you a good idea of
overall rates, but by testing with gnuradio directly you will have a
better idea of your capabilities in real world scenarios).
Jason
I've run into similar problems as well. Here is what helped me get past this problem:
1. Enable Realtime mode (grc can do this for you). You might need to run as root
2. Increasing fusb_nblocks and fusb_block_size. fusb_nblocks = 4096 and fusb_block_size=4096 seemed to work for me.
3. Remounting my etx3 harddisk as ext2.
Hope this helps.
Karthik
