Re: Futexes ain't fast

Am 26.09.2024 um 19:40 schrieb Chris M. Thomasson:

Basically right. Think of hitting a slow path (before resorting to the kernel), then trying to spin a couple of times in user space before we have to hit a kernel call. Akin to a adaptive mutex. If we can avoid a kernel call, well, go ahead and try a couple of times...

Adaptive mutexes often don't make any sense. The locking-frequency has
to be high and the locked-interval needs to be very short to make spin-
ning likely to succeed. That's both not often.

Actually, there is a "method" to do this even with a simple mutex via try_lock. ...

I don't know what try_lock is good for. I've never seen someone using
try_lock. If you need to lock sth. you usually haven't an alternative
to locking.