Re: [v3,11/41] mips: reuse asm-generic/barrier.h

From: Paul E. McKenney
Date: Tue Jan 26 2016 - 19:58:20 EST

On Tue, Jan 26, 2016 at 03:45:23PM -0800, Linus Torvalds wrote:
> On Tue, Jan 26, 2016 at 3:29 PM, Paul E. McKenney
> <paulmck@xxxxxxxxxxxxxxxxxx> wrote:
> >
> > No trailing data-dependent read, so agreed, no smp_read_barrier_depends()
> > needed. That said, I believe that we should encourage rcu_dereference*()
> > or lockless_dereference() instead of READ_ONCE() for documentation
> > reasons, though.
> I agree that that is likely the right thing to do in pretty much all situations.
> In theory, there might be performance situations where we'd want to
> actively avoid the smp_read_barrier_depends() inherent in those, but
> considering that it's only a performance issue on alpha, and we
> probably have all of two or three people using Linux on alpha, it's a
> pretty theoretical performance worry.


Thanx, Paul