On Thu, 3 Aug 2006, Jayaprakash Shanmugam wrote: > Hello All, > How can I make sure I am really running on USB 2.0.
Check that the device reports bcdUSB = 0x0200. You can do this using "lsusb -v" or you can look in /proc/bus/usb/devices. > I just wanted > to measure the data transfer rate in USB 2.0 ? There's no need to measure anything. By definition (according to the USB 2.0 specification) the bit rate in USB 2.0 is 1.5 b/us at low speed, 12 b/us at full speed, and 480 b/us at high speed. But perhaps you want to measure how quickly you can transfer data between your computer and a particular USB device. That's a different matter; it depends more on the device and the computer than it does on USB 2.0. > I tried transferring > some MBs over bulk end point and calculated the time, but this is not > accurate. Why isn't it accurate? Or to put it another way, which part of your measurement is inaccuate: the total number of bytes or the total time? > What else can I do ? > > When I used usb_bulk_msg(), it is not accepting data more than 11K. > Any limitations ??? Are you talking about the usb_bulk_msg function in libusb? That has a limit of 16384 bytes in recent kernels. The usb_bulk_msg routine that's part of the kernel has no limitations on data transfer size. If you want to do large USB data transfers from userspace quickly, use asynchronous transfers and set up a pipeline. If the device you want to test is a USB mass storage device, you can simply time how long it takes to run a "dd" command. 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
