Re: Active waiting with yield()

[Alan Cox <alan@lxorguk.ukuu.org.uk>]

> If I have a race condition that gets triggered just for one user in the 
> world when repeatedly loading & unloading a driver for an hour, and I use 
> yield() to solve it, what's wrong with it? A wait queue increases cache 
> footprint for every user. (even if I use preallocated hashed wait queue, 
> it still eats a cacheline to access it and find out that it's empty)

Reread what I wrote.

You don't need to use a hashed queue, you don't need to even reference
the queue in the normal case. You cost is one variable, which you can
probably sensibly locate, and a predicted jump.

For that you get proper sleeping behaviour, CPU used by other tasks or
guests and you don't hang on hard real time tasks.