On 04/13/2010 07:20 PM, Alexander Graf wrote: >>>> It still needs a lot of love, but definitely an improvement from the >>>> last version. The biggest difference for the performance boost and >>>> stability is discovering that the usbfs in linux limits transactions to >>>> 16k versus the EHCI spec which allows 20k per qTD. I added a hack to >>>> submit which detects 20k requests from a guest and breaks it up into 2 >>>> requests through the host (a 16k and then a 4k). >>> >>> Did someone already bring this up on LKML or wherever usbfs is >>> discussed? Should be fixable, I naively guess. >> >> I submitted the patch to linux-usb and it was nack'ed. The response was >> that memory is allocated in powers of 2 so trying to up the limit from >> 16k to 20k means it will actually want to find 32k of contiguous memory. >> The suggestion was to handle it with multiple requests within qemu. I >> guess libusb does that. > > Any reason we're not using libusb?
Good question. I was wondering the same. I was going to look at converting usb-linux to use libusb1 when I get some time. David > > > Alex >
