[PATCH] hvc_console polling mode timer backoff

[Will Schmidt]

On Thu, 2007-12-04 at 12:33 -0500, Linas Vepstas wrote:
> On Thu, Apr 12, 2007 at 11:14:36AM -0500, Will Schmidt wrote:
> > +/*
> > + * timeout will vary between the MIN and MAX values defined here.  By default
> > + * and during console activity we will use a default MIN_TIMEOUT of 10.  When
> > + * the console is idle, we increase the timeout value on each pass through
> > + * msleep until we reach the max.  This may be noticeable as a brief (average
> > + * one second) delay on the console before the console responds to input when
> > + * there has been no input for some time.
> > + */
> > +#define MIN_TIMEOUT		(10)
> > +#define MAX_TIMEOUT		(2000)
> 
> [...]
> > +				msleep_interruptible(timeout);
> 
> 
> These values are milliseconds (that's what the m in msleep stands for
> or at least it did last time I looked). This 10 is 1/100 of a second,
> which makes a responsive keyboard for even a very very fast typist.
> That's fine.  But 2000 is two seconds, which is longer than the amount 
> of time that I wait before I start panicking that something is broken. 

Well, I usually give my systems at least ten seconds before I start to
worry. :-) 

I did ponder the max value to use.   Though when I sit down at &random&
console in the lab, It often takes a moment for the terminal to warm up,
or for the screen to unblank.   With that in mind, a couple seconds max
for the console does not seem unreasonable to me.

Will see if other folks have an opinion either way.. 

> 
> I'd suggest that maybe 1000 or 750 or 500 is more apropriate.
> 
> --linas