Re: [PATCH v5 01/13] xen/common: add cache coloring common code

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Thu, 4 Jan 2024, Julien Grall wrote:
> Hi,
> 
> On 02/01/2024 09:51, Carlo Nonato wrote:
> > This commit adds the Last Level Cache (LLC) coloring common header, Kconfig
> > options and functions. Since this is an arch specific feature, actual
> > implementation is postponed to later patches and Kconfig options are placed
> > under xen/arch.
> > 
> > LLC colors are a property of the domain, so the domain struct has to be
> > extended.
> > 
> > Based on original work from: Luca Miccio <lucmiccio@xxxxxxxxx>
> > 
> > Signed-off-by: Carlo Nonato <carlo.nonato@xxxxxxxxxxxxxxx>
> > Signed-off-by: Marco Solieri <marco.solieri@xxxxxxxxxxxxxxx>
> > ---
> > v5:
> > - used - instead of _ for filenames
> > - removed domain_create_llc_colored()
> > - removed stub functions
> > - coloring domain fields are now #ifdef protected
> > v4:
> > - Kconfig options moved to xen/arch
> > - removed range for CONFIG_NR_LLC_COLORS
> > - added "llc_coloring_enabled" global to later implement the boot-time
> >    switch
> > - added domain_create_llc_colored() to be able to pass colors
> > - added is_domain_llc_colored() macro
> > ---
> >   xen/arch/Kconfig               | 16 ++++++++++++
> >   xen/common/Kconfig             |  3 +++
> >   xen/common/domain.c            |  4 +++
> >   xen/common/keyhandler.c        |  4 +++
> >   xen/include/xen/llc-coloring.h | 46 ++++++++++++++++++++++++++++++++++
> >   xen/include/xen/sched.h        |  5 ++++
> >   6 files changed, 78 insertions(+)
> >   create mode 100644 xen/include/xen/llc-coloring.h
> > 
> > diff --git a/xen/arch/Kconfig b/xen/arch/Kconfig
> > index 67ba38f32f..aad7e9da38 100644
> > --- a/xen/arch/Kconfig
> > +++ b/xen/arch/Kconfig
> > @@ -31,3 +31,19 @@ config NR_NUMA_NODES
> >       associated with multiple-nodes management. It is the upper bound of
> >       the number of NUMA nodes that the scheduler, memory allocation and
> >       other NUMA-aware components can handle.
> > +
> > +config LLC_COLORING
> > +   bool "Last Level Cache (LLC) coloring" if EXPERT
> 
> While look at the rest of the series, I noticed that SUPPORT.md is not
> updated. Can this be done?
> 
> I think the feature should be in experimental for now. We can decide to switch
> to tech preview before Xen 4.19 is out and the support is completed.
> 
> Stefano, what do you think?

That's reasonable