Re: [PATCH v3] x86/cpu: Use SERIALIZE in sync_core() when available

[Ricardo Neri]

On Thu, Aug 06, 2020 at 04:08:47PM -0700, Dave Hansen wrote:
> On 8/6/20 4:04 PM, Ricardo Neri wrote:
> > 	 * CPUID is the conventional way, but it's nasty: it doesn't
> > 	 * exist on some 486-like CPUs, and it usually exits to a
> > 	 * hypervisor.
> > 	 *
> >  	 * The SERIALIZE instruction is the most straightforward way to
> >  	 * do this as it does not clobber registers or exit to a
> > 	 * hypervisor. However, it is not universally available.
> >  	 *
> > 	 * Like all of Linux's memory ordering operations, this is a
> > 	 * compiler barrier as well.
> > 	 */
> > 
> > What do you think?
> 
> I like what I suggested.  :)
> 
> SERIALIZE is best where available.  Do it first, comment it by itself.
> 
> Then, go into the long discussion of the other alternatives.  They only
> make sense when SERIALIZE isn't there, and the logic for selection there
> is substantially more complicated.

Sure Dave, I think this layout makes sense. I will rework the comments.

Thanks and BR,
Ricardo