You undoubtedly are already aware of some of the things I'm going to say. But I'll say them anyway, just for the record... :-)
On Fri, 6 Oct 2006, Christopher "Monty" Montgomery wrote: > On 10/6/06, Alan Stern <[EMAIL PROTECTED]> wrote: > > > > In my primary use case, the endpoint will lose its bandwidth > > > reservation, > > > > What makes you think that? > > Bandwidth fragmentation. If we release an ISO stream's bandwidth from > the middle of a schedule frame, we cannot currently recover the hole. > EHCI makes rebalancing very difficult, and requires partially shutting > down the schedule to do it. Notice that you didn't answer the question I asked. I asked why you thought the reservation would be lost, and you replied by explaining why the reservation could not be recovered once it was lost. My original question still stands. > > You still don't seem to understand. Kernel latency by itself _cannot_ > > cause a bandwidth reservation to be lost. > > I call bullshit. A single well-placed printk inside the spinlock is > enough latency to cause all the iso streams to lose sync. That > spinlock can also be held be preemptible code. Etc. Again, notice that you didn't address my comment. I said that kernel latency cannot cause a reservation to be lost. You replied by saying that kernel latency can cause a stream to lose sync. That's very different. You can lose sync without losing bandwidth reservation. > > Only the higher-level driver > > can do that, by failing to keep the URB queue non-empty (i.e., by failing > > to resubmit within its completion handler). > > If the HC clock gets to a slot that should be filled and it isn't, > that's loss of sync. If the completion handler isn't called in time, > the completion handler can't resubmit. Etc. Once again: losing sync is different from losing a reservation. 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
