lock contention problem?

[dieterbsd at engineer.com]

> It might be a hardware resource starvation problem. It is possible to 
nice
> umass by simply adding a line like:
>
>                .interval = 2,        /* 2 milliseconds */

Thanks, but it didn't help.  Also tried setting it to 1, 4, and 20.

> http://svn.freebsd.org/changeset/base/217350

Is this supposed to work for 8.0?  Is there more to it than a
couple line change in a .h file?

/usr/src/sys/dev/usb/controller/usb_controller.c: In function 
'usb_attach_sub':
/usr/src/sys/dev/usb/controller/usb_controller.c:434: warning: implicit 
declaration of function 'PI_SWI'
/usr/src/sys/dev/usb/controller/usb_controller.c:434: warning: nested 
extern declaration of 'PI_SWI'

I'm feeding "fwcontrol -u 1 -S /dev/stdin" from a pipe.   The write()
to the pipe took over a second.  Perhaps connected to the lock 
contention
of over a second?  The EAGAIN comes from the writev() roughly 20 lines
from the end of /usr/src/usr.sbin/fwcontrol/fwdv.c.

CPU is 98% idle.  Data rate is only 3.4 MiB/second.