Re: uniform input device packets?
James Michael Mastros (root@jennifer-unix.dyn.ml.org)
Wed, 24 Jun 1998 02:23:16 -0400
On Wed, Jun 24, 1998 at 01:59:54 AM -0400, Allanah Myles wrote:
> On 1998.06.23, Vojtech Pavlik <vojtech@twilight.ucw.cz> wrote:
> > The timestamp - it is needed, so that an application knows in what
> > order events happened, and what time apart they are. Imagine detecting
> > a double click with heavily loaded, and swapping machine. It might be
> > impossible without timestamps.
>
> Is this necessarily true? Your specific example of "system under load"
> really doesn't necessitate timestamping of events. You're supposing
> that when a system is loaded, it will always immediately process it's
> I/O events and preempt whatever is currently executing (probably
> whatever is causing the load at the moment). You may very well be
> correct, but I have a funny feeling that the way things currently
> work is that the I/O queues up, and is drained at next chance. In
> which case, two single-clicks will arrive one after another and
> appear to be a double-click - I haven't verified this but I'm just
> guessing.
Umm... that was what the timestamps were there for. If an app (X, gpm,
svgalib...) gets mouse events, it can't tell anything about the duration
that the real mouse button was down for, only about the time between when it
got mouse events to process. With timestamps, it can tell that. And, BTW,
if a device has an interupt then (in most cases), input from it does
interupt other things that are running. (Keyboards and mice (serial & ps/2)
have interupts (on x86es, anyway).)
-=- James Mastros
PS -- I have another posting on this thread -- my mailreader ate it twice,
my mailserver ate it once. Lets see how vger likes it.
--
True mastery is knowing enough to bullshit the rest.
-=- Me
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