* Peter Hurley <peter@xxxxxxxxxxxxxxxxxx> [2011-08-04 19:09:37 -0400]: > Hi Mat, > > On Thu, 2011-08-04 at 13:37 -0400, Mat Martineau wrote: > > > I had a recent discussion with Gustavo about HCI queuing issues with > > ERTM: > > > > http://www.spinics.net/lists/linux-bluetooth/msg13774.html > > > > My proposal is to move tx queuing up to L2CAP, and have the HCI tx > > task only handle scheduling. Senders would tell HCI they have data to > > send, and HCI would call back to pull data. I've been focused on > > L2CAP - it would be possible to make a similar queuing change to > > SCO/eSCO/LE, but not strictly necessary. > > Would you please clarify this approach (perhaps in a separate thread)? > > For example, how does having tx queues in l2cap_chan (instead of the > hci_conn) solve the latency problems in ERTM when replying to > REJ/SREJ/poll? Won't there potentially be just as much data already > queued up? Is the plan to move the reply to the front of the tx queue > because reqseq won't need to be assigned until the frame is actually > pulled off the queue? Exactly. ERTM connections can get dropped if the too much data is buffered and we need to send final bit for example. > > > This is different from the problem you're solving, but as long as > > we're talking about big changes to HCI tx, I think we could make some > > changes that help out with prioritization and queuing across all > > channels (whether they're going to the same remote device or different > > remote devices). > > > > It could be more efficient to schedule this way since HCI wouldn't > > have to iterate over all of the connections and queues - it would only > > have to review the prioritized list of pending sends. Might be a more > > fitting structure for QoS too. > > Wouldn't this 'prioritized list of pending sends' need to be locked to > prevent update while reading? ISTM that contention might be fairly high > for a single, shared resource like that. > > > Regards, > Peter Hurley > Gustavo -- To unsubscribe from this list: send the line "unsubscribe linux-bluetooth" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
