Re: flock(fd, LOCK_UN) taking 500ms+ ?

Manfred Spraul (manfred@colorfullife.com)
Wed, 02 Oct 2002 23:36:46 +0200

akpm wrote:
> It's not really clear why that yield is in there at all? Unless that
> code is really, really slow (milliseconds) then probably it should just
> be deleted.
>
It looks like a very simple starvation control:

thread 1:
for(;;) {
F_LOCK
<do a few seconds work>
F_UNLCK
}
thread 2:
F_LOCK.

If there is no yield after unlock, thread 2 might never receive the lock.
Is it possible to figure out if someone is waiting on the lock? F_UNLCK
should schedule, if there is a waiter with higher priority.

--
	Manfred






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