[Discuss-gnuradio] NetBSD USB progress

[Joanne M Mikkelson]

Hi all,

As was discussed here earlier (starting from
http://lists.gnu.org/archive/html/discuss-gnuradio/2006-05/msg00045.html
in the list archive), BBN has been working on improving the ugen(4)
driver for NetBSD.

We've now implemented the changes to the driver and it's handling
transfer rates of at least 16 MB/s well.  According to benchmark_usb.py
(and test_digital_loopback*) in gnuradio-examples, we are getting 32
MB/s throughput (16 in each direction). Also, the test_usrp_standard_rx
and test_usrp_standard_tx programs indicate we're almost getting 25.6
MB/s one-way (decimation 10 and interpolation 20), typically with 0-2
overruns or underruns.

This is much improved over ~4 MB/s but the next step is to work on
optimizing what's needed to reach 32 MB/s reading or writing.  If
you're interested, the current driver work can be found at:
    http://acert.ir.bbn.com/cvs/?group=netbsd
primarily in:
    http://acert.ir.bbn.com/viewvc/netbsd/netbsd/src/sys/dev/usb/


Also, interestingly, benchmark_usb always fails for 2 MB/s even
though the other rates are fine.  I don't know yet why that might be,
but it always looks about like this, always around 940k samples:
    gr_check_lfsr_32k: enter_SEARCHING at offset        0 (0x00000000)
    gr_check_lfsr_32k: enter_LOCKED at offset     1452 (0x000005ac)
    gr_check_lfsr_32k: enter_SEARCHING at offset   947028 (0x000e7354)
    usb_throughput = 2M
    ntotal    = 1000000
    nright    = 945576
    runlength = 0
    delta     = 1000000
    FAILED

Joanne