[PATCH 06/11] qspinlock: Optimize pending bit

Paolo Bonzini
2014-06-18T11:42:13Z

Il 15/06/2014 14:47, Peter Zijlstra ha scritto:
> XXX: merge into the pending bit patch..

Agree, or if not move it right after the pending bit patch, before the
NR_CPUS optimization.

Paolo

> It is possible so observe the pending bit without the locked bit when
> the last owner has just released but the pending owner has not yet
> taken ownership.
>
> In this case we would normally queue -- because the pending bit is
> already taken. However, in this case the pending bit is guaranteed to
> be released 'soon', therefore wait for it and avoid queueing.
>
> Signed-off-by: Peter Zijlstra <peterz at infradead.org>