On Fri, Jun 24, 2005 at 11:58:53PM +0200, Petar Bogdanovic wrote:
> Hello,
> 
> since a few weeks, my laptop is able to do 'hi-speed'-USB (USB-2.0) with 
> NetBSD 3.99.7 and because people say, USB-2.0 is about real speed for
> real men, I wanted to test my two USB-2.0-devices (a 40GB-hard-drive 
> [sd0] and a 128MB-memory-stick [sd1]).
> 
> The results are ok, but they don't come close to the promised 480Mb/s
> resp. 60MB/s:
> 
> # dd if=/dev/zero of=/dev/rsd0d bs=2048k count=512
> 512+0 records in
> 512+0 records out
> 1073741824 bytes transferred in 46.022 secs (23331055 bytes/sec)
> # dd if=/dev/rsd0d of=/dev/null bs=2048k count=512
> 512+0 records in
> 512+0 records out
> 1073741824 bytes transferred in 36.855 secs (29134223 bytes/sec)
> 
> # dd if=/dev/zero of=/dev/rsd1d bs=2048k count=62
> 62+0 records in
> 62+0 records out
> 130023424 bytes transferred in 25.077 secs (5184967 bytes/sec)
> # dd if=/dev/rsd1d of=/dev/null bs=2048k count=62
> 62+0 records in
> 62+0 records out
> 130023424 bytes transferred in 27.186 secs (4782734 bytes/sec)
> 
About 25MB/s for a disk or 5MB/s for a flash is normal. It is faster
than usb1, hence it benefits from USB2 connection.

The speed may be limited by the amount of data the actual storage memory
can generate or the cpu speed because USB2 causes heavy cpu load (at
least with Linux and Windows - I guess it is a limitation of the host
adapter design).

Thanks

Michal Suchanek