On Sat, Jun 18, 2016 at 04:46:20PM +0800, Boqun Feng wrote: > On Fri, Jun 17, 2016 at 02:17:27PM -0400, Waiman Long wrote: > > keep the xchg() function as it is or use smp_store_release(&next->locked, > > 1). So which one is a better alternative for ARM or PPC? > > > > For PPC, I think xchg_release() + smp_store_release() is better than the > current code, because the former has two lwsync while the latter has two > sync, and sync is quite expensive than lwsync on PPC. > > I need to leave the ARM part to Will ;-)
I doubt there's much in it, but xchg() has DMB + release, so xchg_release + smp_store_release is probably slightly better for us too. Will
