On Wed, 2016-04-13 at 10:43 -0700, Will Deacon wrote: > On Tue, Apr 12, 2016 at 08:02:17PM -0700, Jason Low wrote: > > For qspinlocks on ARM64, we would like to use WFE instead > > of purely spinning. Qspinlocks internally have lock > > contenders spin on an MCS lock. > > > > Update arch_mcs_spin_lock_contended() such that it uses > > the new smp_cond_load_acquire() so that ARM64 can also > > override this spin loop with its own implementation using WFE. > > > > On x86, it can also cheaper to use this than spinning on > > smp_load_acquire(). > > > > Signed-off-by: Jason Low <jason.l...@hp.com> > > FWIW, we just override arch_mcs_spin_lock_contended entirely for arch/arm/ > and use wfe there so we could do the same for arm64 in mainline already.
Right, I was also thinking about that, although when we use smp_cond_load_acquire() in the generic implementation, would we just end up overriding it for the arch/arm64 version with the same thing? :) Jason
