Re: [PATCH V2 0/6][RFC] futex: FUTEX_LOCK with optional adaptivespinning

From: Thomas Gleixner
Date: Tue Apr 06 2010 - 14:18:38 EST

On Tue, 6 Apr 2010, Alan Cox wrote:

> > > IMO the best solution is to spin in userspace while the lock holder is
> > > running, fall into the kernel when it is scheduled out.
> >
> > That's just not realistic as user space has no idea whether the lock
> > holder is running or not and when it's scheduled out without a syscall :)
> Which is the real problem that wants addressing and can be addressed very
> cheaply. That would bring us up to par with 1970s RTOS environments ;)

Well, 1970's RTOSes had other features as well like preemption disable
mechanisms and other interesting stuff. I hope you're not going to
propose that next to bring us up to par with those :)


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