I maintain a program to communicate with a Creative Nomad II MG MP3 player (http://www.swiss.ai.mit.edu/~cph/nomad.php) through usbdevfs. Recently I've been trying to understand why file transfers to and from the device are so slow (about 55 kB/s rates). When doing the same operations using Creative's software running on the same hardware under Windows XP, performance is about 10 times faster, which is more along the lines of what I would naively expect.
This motivates my questions: 1. The problem, according to my crude user-space measurements using gettimeofday(), is that a bulk transfer of 4096 bytes takes approximately 70 milliseconds to complete. Does this seem reasonable? It seems like a very long time for such a small amount of data. 2. The windows software, according to sniffusb, is using much bigger bulk transfer packets -- at least 64 kB. But the usbdevfs interface specifically limits the packet size to 4096 bytes. Why is this limit in place? Shouldn't I be able to generate bulk transfers in larger sizes? Please reply directly to me as I don't read this list. Chris _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
