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

From: Manfred Spraul (manfred@colorfullife.com)
Date: Wed Oct 02 2002 - 16:36:46 EST

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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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Next message: Denis Vlasenko: "Re: [PATCH] cli()/sti() fix for drivers/net/depca.c"
Previous message: Sam Ravnborg: "Re: include/asm/irq_vectors.h not found"
Maybe in reply to: John Levon: "flock(fd, LOCK_UN) taking 500ms+ ?"
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