extremely bad USB/msdos performance

[Matthew Dillon]

:The performance for writing to msdosfs on an ehci usb device is 
:pathetic.  I'm getting ~500KB/sec, while other OS can do at least 6MB.
:
:the rsync process is most of the time in "iowait", "biows", "biord".

    Try mounting it async.  If that doesn't work you'd have to delve
    into the filesystem code and asynchronize any synchronous bwrite()s
    you see (using bdwrite()), and/or potentially change bawrite()s to
    bdwrite()s.

					-Matt