Re: [PATCH 2/3] x86/topology: Fix AMD core count
From: Huang Rui
Date: Mon Mar 21 2016 - 05:46:11 EST
On Mon, Mar 21, 2016 at 09:21:29AM +0100, Peter Zijlstra wrote:
> On Mon, Mar 21, 2016 at 11:07:46AM +0800, Huang Rui wrote:
> > > > The issue is that Linux assumes:
> > > >
> > > > nr_logical_cpus = nr_cores * nr_siblings
> > > >
> > > > But AMD reports its CU unit as 2 cores, but then sets num_smp_siblings
> > > > to 2 as well.
> > But I am confused with c->x86_max_cores /= smp_num_siblings, what is
> > the real meaning of c->x86_max_cores here for AMD, the whole compute
> > unit numbers per socket?
> Yes, with the whole Compute Unit being the Core, each logical CPU
> becomes a Thread. This is the direct consequence of using the SMT
> topology to model the CU thing.
OK, maybe, we would better add a comment to explain here. :-)