High Resolution Timer DOS

[matthieu castet]

Hi,

some programs need to do some short of busyloop. It was often 
implemented as :

while (1) {
	if (can_do_stuff) {
		do_stuff();
	}
	else
		//sleep a very short of time
		usleep(1);
}

usleep(1) or equivalent where used instead of sched_yield, because of 
some priority issue. IIRC doing sched_yield, make the process appears 
like an interactive process, so it has better priority and get call more 
often.

But now if high res timer are enabled, these programs while cause 
something like a DOS : the context switch per second will be bigger than 
500 000 and the cpu usage will be very high.


I don't know if such problem are already know, but I believe a warning 
about such issues should be in the Kconfig description.


Matthieu
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