On Wed, Oct 27, 2010 at 4:57 PM, Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx> wrote: > On Wed, Oct 27, 2010 at 12:09:58PM -0500, Bill Gatliff wrote: >> This patch moves the tail pointer up one event on a buffer >> overflow, which "consumes" the oldest event in the buffer >> to make room for the incoming event. Thus, although data >> is lost due to the overflow (which is unavoidable), the >> data that remains is both recent and still time-ordered. >> > > It does not really matter... You are losing part of the hardware state > regardless so the packet is invalid anyway. What would probably make > more sense is to ignore all events up until next packet boundary > (EV_SYN/SYN_REPORT) so userspace would get most up-to-date _full_ packet > (when it catches up). That's an interesting idea, actually. Maybe the subject of a future patch. :) I still think my patch is a genuine improvement as-is, however. But perhaps not the final word on the issue. For example, how do you recall the events that userspace has already digested from the current packet? One alternative is to not queue a packet until the whole packet is ready, but that will introduce latency. I don't like that approach, either. Hmmm... I suppose another possibility is to always reserve enough room for an EV_SYN/SYN_REPORT event, and never discard those events. Then userspace will always see a properly-terminated packet, but in a collision it would receive a partial-but-properly-terminated packet. b.g. -- Bill Gatliff bgat@xxxxxxxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
