NetBSD USB progress

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

On Mon, Jun 26, 2006 at 02:39:32PM -0400, Joanne M Mikkelson wrote:

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.

Definitely improved!

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/

delta     = 1000000
FAILED

Joanne

There is a long outstanding bug in benchmark_usb that has it be
unreliable. It’s been a long time since I looked at it. The problem
could be in the lfsr synchronization.

test_usrp_standard_{tx, rx} seem to work fine, however.

Eric

There is a long outstanding bug in benchmark_usb that has it be
unreliable. It’s been a long time since I looked at it. The problem
could be in the lfsr synchronization.

Yeah, I saw the comment in the file. What I find interesting about it
is that it’s only failing for the slowest transfer rate, and the
others are fine. So they are getting past that same point in the
sequence with no trouble, and they’re also not all failing ~60k
samples before the end…

It’s probably indeed not very critical to figure it out, but it does
strike me as odd that it’s unreliable in this particular way.

Joanne

Many apologies for the delay in responding; somehow I missed this
message.

Is there a consolidated patch file that would make it easier to apply against
the current NetBSD source tree?

Attached is a patch file for the top level of the NetBSD source,
including all the files changed. config(8) will automatically create
the enigmatic opt_ugen_bulk_ra_wb.h file. To actually include the
changes in your kernel compile (they are not enabled by default), add
“options UGEN_BULK_RA_WB” to your kernel config.

Joanne

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. Â 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/

Is there a consolidated patch file that would make it easier to apply
against
the current NetBSD source tree?

cheerio Berndt

I forgot to mention that I’ve put files for a change to the USRP fusb
driver to take advantage of the new ugen driver up at:
http://acert.ir.bbn.com/viewvc/adroitgrdevel/adroitgrdevel/radio_test/usb/fusb_netbsd/
for now. The files go in the corresponding directories in the usrp
source tree.

This fusb_netbsd code was developed for testing the driver work, and
won’t work terribly well with the unmodified ugen. But hopefully
it’ll help out anyone trying out the ugen changes at this point.

Joanne

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