On Wed, Jan 06, 2016 at 04:22:12PM +0100, Peter Stuge wrote: >>> Our interface for zero copy reads/writes is O_DIRECT, and that requires >>> not special memory allocation, just proper alignment. >> But that assumes you are using I/O using read()/write(). There's no way you >> can shoehorn USB isochronous reads into the read() interface, O_DIRECT or not. > How about aio? I don't really see how; a USB device does not look much like a file. (Where would you stick the endpoint, for one? And how would you ever submit an URB with multiple packets in it, which is essential?) It feels a bit like trying to use UDP sockets with only read() and write(). In any case, the usbfs interface already exists and is stable. This is about extending it; replacing it with something new from scratch to get zerocopy would seem overkill. /* Steinar */ -- Software Engineer, Google Switzerland -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
