Feature requests for sleep and a new program

[Johannes Nieß]

Hi,

I'd like to propose two new features to "sleep":

1) Sub-Second resolution

I understand that shell scripts never won't get real time precision, but with 
today's processing speed something in the order of several 10 ms should be 
possible. It could be implemented by allowing floats for time arguments or 
(may be easier) with a new unit of "ms" (miliseconds). I'm quite sure the 
structures are already there.

2) Wait for ms multiple

You can't control loop cycle times with sleep: If you "sleep 1" and your loop 
payload takes 0.1 second you end up with a 1.1+X second cycle time. If we 
wait for a timer modulo interval to flip over, we have exact control over 
loop cycle time. An implementation could look like:

a=timerfunction mod interval
aa=a
while a>= aa
        sleep 10 ms
        a=aa
        a=timerfunction mod interval
wend

We could use a "-m" parameter for this changed behavior


A new program could supplement "nice". In some (rare) cases you want to 
control the maximum CPU load a program can generate. It could be dome via 
signals. To allow a maximum CPU load of 0.5 for a program you can send a 
TSTOP signal , wait 0.5 seconds, send CONT and wait 0.5 seconds and so on.

I know that programs can intercept signals but it'll work for most programs.


Thank you very much

Johannes Nieß