Re: [Discuss-gnuradio] File sink causes "S" errors

On Tue, Oct 5, 2010 at 9:17 PM, Thomas Hobiger <hobiger@nict.go.jp> wrote:
> When doing a few samples with decimation of 8 nothing happens.
>
>>  ./rx_streaming_samples -f 1.575G -d 8 -N 1000000000 -s -o /SSD/test.bin
>
>> ./rx_streaming_samples -f 1.575G -d 8 -N 2000000000 -s -o /SSD/test.bin
>
>
> But when taking more data
>
>> ./rx_streaming_samples -f 1.575G -d 8 -N 4000000000 -s -o /SSD/test.bin
> SSSSSSSSSS....

The default receive buffer in the Linux kernel is relatively small, I
think just over 100k. It may not help, but would be worth a shot to
increase the buffer size to smooth out the data flow. Use "sysctl
net.core.rmem_max" and "sysctl net.core.rmem_default" to see the max
and default you have now, and "sysctl -w net.core.rmem_max=4194304"
(or whatever) to set them. The default is what all new sockets are
allocated, and you can use setsockopt to set the SO_RCVBUF option on
the socket to change it after that (up to the max of course). I'm not
sure if the usrp2 driver is currently trying to increase that buffer
size or not, but if your max is low it won't help much.

Jared

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