Re: [PATCH 2/3 v2] futex: avoid double wake up in futex_wake() on -RT

From: Davidlohr Bueso
Date: Sun Apr 12 2015 - 23:03:25 EST

On Fri, 2015-04-10 at 18:11 +0200, Sebastian Andrzej Siewior wrote:
> This patch delays the wakeup of the process untill
^^^ until

> the hb->lock is
> dropped to avoid boosting + context switch to obtain the lock.

Doing the wakeups while holding the lock is also a general performance
issue for futex_wake. The problem being dealing with spurious wakeups
(wacky drivers), which makes no difference wrt nr_wake.


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