cvs commit: src/sys/isa psm.c

[Alfred Perlstein]

* Eivind Eklund <eivind at FreeBSD.org> [031211 04:08] wrote:
> On Thu, Dec 11, 2003 at 03:28:11AM -0800, Alfred Perlstein wrote:
> >   Log:
> >   Significantly reduce the "jitter" that is typical for PS/2 mice
> >   when using a KVM.
> [...]
> >   
> >   The actual solution that appears to offer the best clamping of
> >   jitter is to buffer the mouse packets if we've not seen mouse
> >   activity for more than .5 seconds.  Then waiting to flush that data
> >   for 1/20th of a second.  If within that 20th of a second we get any
> >   packets that do fail the weak test we drop the entire queue and
> >   back off accepting data from the mouse for 2 seconds and then repeat
> >   the whole deal.
> 
> Have you tested this with enough high speed interactive games?  50ms 
> (1/20s) is three to four frames, and quite a lot of delaying input.  
> There are a number of types of games that require faster response than 
> this.  I'm not entirely sure how it influences most mouse-run games - I 
> know that at least some 2D fighting games with joystick absolutely 
> required 1-frame (20ms) response on 50Hz displays.   

There is only a delay if the mouse has been idle for .5 seconds,
otherwise the reaction is immediate.  I guess we could tune that
up to 2 seconds, it's also tunable via sysctls.  Feedback, testing
and tweaking are encouraged, this is -current afterall. :)

> [...]
> >   Lastly I'd like to note that my experience with Windows shows me that
> >   somehow the Microsoft PS/2 driver typically avoids this problem, but
> >   that may only be possible when running the mouse in a dumb-ed down PS/2
> >   mode that Belkin recommends on their site.
> 
> It'd be interesting to know what they do.

Yah, me too. :)

-- 
- Alfred Perlstein
- Research Engineering Development Inc.
- email: bright at mu.org cell: 408-480-4684