On Tue, 5 Dec 2006, Oliver Neukum wrote: > > Stated differently, USB 2.0 has a theoretical max of 480Mbps, which is > > 60 MB/sec, but in actual practice only about 50% of that is attainable. > > That's not really fair. The protocol itself makes reservations of bandwidth > for control transfers and real time applications.
And the protocol itself has bandwidth overhead. The maximum possible number of 512-byte bulk transfers per microframe is 13, even without isochronous or control transfers. That amounts to 512*13*8 bytes/ms or 51 MB/s. usb-storage doesn't make full use of the available bandwidth, but the largest bottleneck must be the devices themselves (or their USB interfaces). Alan Stern ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
