The USRP uses bulk transfers, and avoids large reads to keep latencies
down.

  I think the problem you experience entirely lies within the file
  "usb/ugen.c".

Agreed; perhaps that was too implicit.  The intent was to modify
ugen.c to have multiple reads going at once.  But, this is different
semantics than ugen currently has, where bus transactions only happen
when read is called.  So we need something clean and backwards
compatible in NetBSD that's usable by the USRP user-space library.

The ugen.c on your website looks quite different from NetBSD-current's
ugen.c.  Can you explain the lineage and differences?

-- 
        Greg Troxel <gdt@ir.bbn.com>