On Monday 28 October 2002 04:14 pm, Johannes Erdfelt wrote: > On Mon, Oct 28, 2002, anton wilson <[EMAIL PROTECTED]> wrote: > > On Monday 28 October 2002 04:01 pm, Johannes Erdfelt wrote: > > > On Mon, Oct 28, 2002, anton wilson <[EMAIL PROTECTED]> wrote: > > > > On Friday 25 October 2002 06:36 pm, Johannes Erdfelt wrote: > > > > > On Fri, Oct 25, 2002, anton wilson <[EMAIL PROTECTED]> wrote: > > > > > > In a USB driver, I'm chaining ISO urbs by resubmitting the URBS > > > > > > in the completion handler. I also time the calls to the urb > > > > > > completion handlers using do_gettimeofday(). Most of the time, > > > > > > the time between interrupts is at most 1.01 ms, but occasionally > > > > > > there may be a 2 ms time inbetween interrupts. By occasional I > > > > > > mean 1 or 2 times every 10 seconds. Is this normal behaviour? And > > > > > > what kinds of things could cause an additional 1 ms delay between > > > > > > calls to the completion handler? > > > > > > > > > > What HC are you using? What kernel? > > > > > > > > linux 2.4.18 with 0(1) - preemptive and low-latency - > > > > UHCI > > > > > > How many Isochronous buffers are you scheduling at one time? > > > > > > Which UHCI driver? > > > > the usb-uhci module v1.275 ... > > I'd say 4 per device. 2 read and 2 write > > I'm not quite sure if enqueuing all 4 at once is necessary to achieve > > sends and recieves every ms. That's how the driver was before it was > > handed to me... The urbs are re-submitted in the completion handler. > > 3 devices are being used right now. > > That's probably not enough. There is no guarantee that the callback will > happen quickly enough that you can reschedule it for frame afterwards.
So right now, I submit 2 urbs for writes in the beginning and then they resubmit themselves. If that's not enough, is there some particular quantity that is generally enough to have 1 completion callback per millisecond? Does the number vary according to the hardware or the HC? Thanks, Anton > > You may want to try using multiple buffers (and thusly multiple frames) > per URB, or use some more URB's. > > JE > > > > ------------------------------------------------------- > This sf.net email is sponsored by:ThinkGeek > Welcome to geek heaven. > http://thinkgeek.com/sf > _______________________________________________ > [EMAIL PROTECTED] > To unsubscribe, use the last form field at: > https://lists.sourceforge.net/lists/listinfo/linux-usb-devel ------------------------------------------------------- This sf.net email is sponsored by:ThinkGeek Welcome to geek heaven. http://thinkgeek.com/sf _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
