Re: [PATCH] locking/osq: Drop the overload of osq lock

[Peter Zijlstra]

On Sun, Jun 26, 2016 at 12:59:01PM +0800, panxinhui wrote:
> 
> > å 2016å6æ26æï03:12ïPeter Zijlstra <peterz@xxxxxxxxxxxxx> åéï
> > 
> > On Sun, Jun 26, 2016 at 01:27:51AM +0800, panxinhui wrote:
> > 
> >> by the way I still think mutex_unlock has a big overload too. 
> > 
> > Do you mean overhead?
> > 
> oh, maybe you are right. 

> mutex_unlock âs implementation uses inc_return variant on  ppc, and
> thatâs expensive. I am thinking of using  cmpxchg instead. 

That statement doesn't make any sense. PPC is an LL/SC arch, inc_return
and cmpxchg are the 'same' LL/SC loop.