Re: [AD] uthreads.c revisited

[Elias Pschernig <elias@xxxxxxxxxx>]

On Tue, 2004-07-13 at 19:53 -0700, Chris wrote:
> I'm just going through this in my head... in the threaded background 
> process manager for input and sound, we have this:
> 
>        /* run the callbacks for each 10ms elapsed, but limit to 18ms */
>        if (interval > 18000)
>           interval = 18000;
>        while (interval > 10000) {
> 
> However, I think I may have an issue or two with it. First off, I 
> understand that the interval is clamped to 18ms so it doesn't run away 
> due to a cpu spike or process pause or something. But, I'd want to ask 
> if clamping is necessary? And if it is, I think it should be changed to 
> something like this:
> 
>        if (interval > 20000)
>           interval = 20000;
>        while (interval >= 10000) {
> or
>        if (interval > 18000)
>           interval = 18000;
>        if (interval >= 10000) {
> 
> In both cases, the bg processes run when the interval is >= 10ms, 
> instead of only > 10ms. For the first, it increases the max clamp value 
> to 20ms, so the while loop would run twice if it was that far behind 
> (this could be what the original clamp was aiming for but due to 
> MAX_INT, couldn't get higher than 17.99ms). For the second, it changes 
> the while to an if, since even if interval was 20ms or more, it would've 
> been clamped to 18ms and the while loop would only run once anyway 
> (granted optimizations would clear this out, but it doesn't look very 
> clean).
> 

Not sure. Using 18000 vs 20000 is completely arbitrary. Maybe we
actually set it even higher, sometimes my HDD seems to block the
complete system for something like half a second it seems :| And the
while vs if, if there's no while, we are limited to whatever is the
timeslice time at which select() returns. I think we can safely leave it
as it is now.

-- 
Elias Pschernig