Re: [PATCH v3] x86/cpu: Use SERIALIZE in sync_core() when available
From: Ricardo Neri
Date: Thu Aug 06 2020 - 19:39:26 EST
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,