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

From: Peter Zijlstra
Date: Tue Apr 06 2010 - 11:29:40 EST

On Mon, 2010-04-05 at 13:23 -0700, Darren Hart wrote:
> Lastly, I should mention that these results all underperform a simple
> pthread_mutex_lock()/pthread_mutex_unlock() pair. I'm looking into why but felt
> I was overdue in sharing what I have to date. A test comparing this to a
> sched_yield() style userspace spinlock would probably be more appropraite.

This really should be able to out-perform a regular pthread_mutex_lock()
we saw a significant performance gain when we added adaptive spins to
the kernel mutex implementation, so I'd expect a gain on the futex one
as well.

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