On Tue, Jun 05, 2001 at 10:03:45PM +0200, Pavel Machek wrote:
> What impact has depth-first on usb bandwidth?
>
> With FSBR I get 700KB/sec with usb-to-usb.
>
> With depth-first but no FSBR I get 300..400KB/sec with usb-to-usb
> networking. Does it have something to do with frames starting in the
> middle of usb frame?
In theory, depth first can get the highest bandwidth, since the TDs for one
target are processed without pause. But practically, most devices NAK after
a few packets, which stops the processing of that queue until the next frame.
If the NAK appears in the beginning, the whole frame is "lost" for that
device, if no FSBR is used. With FSBR, the device is tried again and again,
until it new accepts data.
--
Georg Acher, [EMAIL PROTECTED]
http://www.in.tum.de/~acher/
"Oh no, not again !" The bowl of petunias
_______________________________________________
[EMAIL PROTECTED]
To unsubscribe, use the last form field at:
http://lists.sourceforge.net/lists/listinfo/linux-usb-devel
