Re: Intel Memory Ordering White Paper

Alan Cox
2007-09-08T10:22:45Z

On Sat, 8 Sep 2007 18:54:57 +1000
Nick Piggin <nickpiggin@yahoo.com.au> wrote:

> On Saturday 08 September 2007 08:26, Jesse Barnes wrote:
> > FYI, we just released a new white paper describing memory ordering for
> > Intel processors:
> > http://developer.intel.com/products/processor/manuals/index.htm
> >
> > Should help answer some questions about some of the ordering primitives
> > we use on i386 and x86_64.
>
> So, can we finally noop smp_rmb and smp_wmb on x86?

Nakked-by: Alan Cox <alan@redhat.com>

You can only no-op it on 64bit Intel processors. On 32bit it needs to be
conditional on whether your processor family (or back compat for it) as
the Pentium Pro has some serious store ordering errata (hence the way it
needs lock decb for spin_unlock)

Alan