Re: [PATCH] x86: Consider multiple nodes in a single socket to be "sane"

Heiko Carstens
2014-09-16T10:07:32Z

On Tue, Sep 16, 2014 at 01:17:44AM -0700, Dave Hansen wrote:
> >> The sysfs effects here cause an issue with the hwloc tool where
> >> it gets confused and thinks there are more sockets than are
> >> physically present.
> >
> > Meh, so then we need another mask.
>
> s390 has this concept of a "book" although it's not obvious at all where
> this fits in to the hierarchy to me. The help text and comments are
> pretty funny:
>
> Book scheduler support improves the CPU scheduler's decision
> making when dealing with machines that have several books.
>
> Wow, really? Book scheduling helps with books? I would have never
> guessed.

I'm glad the help text did enlighten you.

> Wish I knew what a book was. :) Google helped a bit:
> http://sysmagazine.com/posts/150430/
> but it's still not clear. I think a book is below a node?
>
> SMT <= LLC <= MC <= BOOK <= NODE

This one is correct. s390 does not have NUMA support. So we have one
node with multiple books.