os_evt_wait efficienty

Hello,

I am trying to program a task management system with some os_evt_set/wait functions.
Whenever task receives STOP flag it halts and starts upon receiving a START flag.

So basically all tasks have a os_dly_wait(flag, 0xFFFF) in their loop.

What I wanted to ask: is this a power-efficient way to halt task operations or is it better to destroy them?

I couldn't find any documentation on how actually os_evt_wait() function works.
Is it somehow similar to

for(1){
os_dly_wait();
}

or does it use some sort of interrupts?

Thanks!

All the best,
G.