RE: [PATCH 02/37] xen: introduce a Kconfig option to configure NUMA nodes number

[Wei Chen <Wei.Chen@xxxxxxx>]

Hi Stefano,

> -----Original Message-----
> From: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> Sent: 2021年9月24日 7:45
> To: Wei Chen <Wei.Chen@xxxxxxx>
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx; sstabellini@xxxxxxxxxx; julien@xxxxxxx;
> Bertrand Marquis <Bertrand.Marquis@xxxxxxx>
> Subject: Re: [PATCH 02/37] xen: introduce a Kconfig option to configure
> NUMA nodes number
> 
> On Thu, 23 Sep 2021, Wei Chen wrote:
> > Current NUMA nodes number is a hardcode configuration. This
> > configuration is difficult for an administrator to change
> > unless changing the code.
> >
> > So in this patch, we introduce this new Kconfig option for
> > administrators to change NUMA nodes number conveniently.
> > Also considering that not all architectures support NUMA,
> > this Kconfig option only can be visible on NUMA enabled
> > architectures. Non-NUMA supported architectures can still
> > use 1 as MAX_NUMNODES.
> 
> This is OK but I think you should also mention in the commit message
> that you are taking the opportunity to remove NODES_SHIFT because it is
> currently unused.
> 
> With that:
> 
> Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> 
> 

Thanks, I will update it in next version.

> > Signed-off-by: Wei Chen <wei.chen@xxxxxxx>
> > ---
> >  xen/arch/Kconfig           | 11 +++++++++++
> >  xen/include/asm-x86/numa.h |  2 --
> >  xen/include/xen/numa.h     | 10 +++++-----
> >  3 files changed, 16 insertions(+), 7 deletions(-)
> >
> > diff --git a/xen/arch/Kconfig b/xen/arch/Kconfig
> > index f16eb0df43..8a20da67ed 100644
> > --- a/xen/arch/Kconfig
> > +++ b/xen/arch/Kconfig
> > @@ -17,3 +17,14 @@ config NR_CPUS
> >       For CPU cores which support Simultaneous Multi-Threading or
> similar
> >       technologies, this the number of logical threads which Xen will
> >       support.
> > +
> > +config NR_NUMA_NODES
> > +   int "Maximum number of NUMA nodes supported"
> > +   range 1 4095
> > +   default "64"
> > +   depends on NUMA
> > +   help
> > +     Controls the build-time size of various arrays and bitmaps
> > +     associated with multiple-nodes management. It is the upper bound
> of
> > +     the number of NUMA nodes the scheduler, memory allocation and
> other
> > +     NUMA-aware components can handle.
> > diff --git a/xen/include/asm-x86/numa.h b/xen/include/asm-x86/numa.h
> > index bada2c0bb9..3cf26c2def 100644
> > --- a/xen/include/asm-x86/numa.h
> > +++ b/xen/include/asm-x86/numa.h
> > @@ -3,8 +3,6 @@
> >
> >  #include <xen/cpumask.h>
> >
> > -#define NODES_SHIFT 6
> > -
> >  typedef u8 nodeid_t;
> >
> >  extern int srat_rev;
> > diff --git a/xen/include/xen/numa.h b/xen/include/xen/numa.h
> > index 7aef1a88dc..52950a3150 100644
> > --- a/xen/include/xen/numa.h
> > +++ b/xen/include/xen/numa.h
> > @@ -3,14 +3,14 @@
> >
> >  #include <asm/numa.h>
> >
> > -#ifndef NODES_SHIFT
> > -#define NODES_SHIFT     0
> > -#endif
> > -
> >  #define NUMA_NO_NODE     0xFF
> >  #define NUMA_NO_DISTANCE 0xFF
> >
> > -#define MAX_NUMNODES    (1 << NODES_SHIFT)
> > +#ifdef CONFIG_NR_NUMA_NODES
> > +#define MAX_NUMNODES CONFIG_NR_NUMA_NODES
> > +#else
> > +#define MAX_NUMNODES    1
> > +#endif
> >
> >  #define vcpu_to_node(v) (cpu_to_node((v)->processor))
> >
> > --
> > 2.25.1
> >