Re: [PATCH -v3 7/8] locking: Move smp_cond_load_acquire() and friends into asm-generic/barrier.h
From: Will Deacon
Date: Wed Jun 01 2016 - 08:13:25 EST
On Wed, Jun 01, 2016 at 02:06:54PM +0200, Peter Zijlstra wrote:
> On Wed, Jun 01, 2016 at 01:00:10PM +0100, Will Deacon wrote:
> > On Wed, Jun 01, 2016 at 11:31:58AM +0200, Peter Zijlstra wrote:
> > > Will, since ARM64 seems to want to use this, does the below make sense
> > > to you?
> > Not especially -- I was going to override smp_cond_load_acquire anyway
> > because I want to build it using cmpwait_acquire and get rid of the
> > smp_acquire__after_ctrl_dep trick, which is likely slower on arm64.
> > So I'd be happier nuking cmpwait from the generic interfaces and using
> > smp_cond_load_acquire everywhere, if that's possible.
> Works for me; but that would loose using cmpwait() for
> !smp_cond_load_acquire() spins, you fine with that?
> The two conversions in the patch were both !acquire spins.
Maybe we could go the whole hog and add smp_cond_load_relaxed?