Re: [PATCH v2] introduce atomic_pointer to fix a race condition in cancelable mcs spinlocks

H. Peter Anvin
2014-06-02T17:39:39Z

On 06/02/2014 10:25 AM, Waiman Long wrote:
>
> Doing an xchg is a very expensive operation compared with ACCESS_ONCE. I
> will not suggest doing that to make it right for PA-RISC at the expense
> of performance in other architectures.
>

And of course, this gets into the toxic question: what are reasonable
minimum requirements for Linux? How far do we need to stretch to
support niche architectures which have very small (Linux) userbases?

-hpa