Re: [PATCH v12 5/5] arm64, mm, numa: Add NUMA balancing support for arm64.

[David Daney]

On 02/26/2016 10:53 AM, Will Deacon wrote:
> On Mon, Feb 22, 2016 at 05:58:23PM -0800, David Daney wrote:
> > From: Ganapatrao Kulkarni <gkulkarni@xxxxxxxxxxxxxxxxxx>
> >
> > Enable NUMA balancing for arm64 platforms.
> > Add pte, pmd protnone helpers for use by automatic NUMA balancing.
> >
> > Reviewed-by: Robert Richter <rrichter@xxxxxxxxxx>
> > Signed-off-by: Ganapatrao Kulkarni <gkulkarni@xxxxxxxxxxxxxxxxxx>
> > Signed-off-by: David Daney <david.daney@xxxxxxxxxx>
> > ---
> >   arch/arm64/Kconfig               |  1 +
> >   arch/arm64/include/asm/pgtable.h | 15 +++++++++++++++
> >   2 files changed, 16 insertions(+)
> >
> > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> > index 9f0972a..6e22503 100644
> > --- a/arch/arm64/Kconfig
> > +++ b/arch/arm64/Kconfig
> > @@ -11,6 +11,7 @@ config ARM64
> >   	select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
> >   	select ARCH_USE_CMPXCHG_LOCKREF
> >   	select ARCH_SUPPORTS_ATOMIC_RMW
> > +	select ARCH_SUPPORTS_NUMA_BALANCING
> >   	select ARCH_WANT_OPTIONAL_GPIOLIB
> >   	select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
> >   	select ARCH_WANT_FRAME_POINTERS
> > diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
> > index bf464de..5af9db2 100644
> > --- a/arch/arm64/include/asm/pgtable.h
> > +++ b/arch/arm64/include/asm/pgtable.h
> > @@ -346,6 +346,21 @@ static inline pgprot_t mk_sect_prot(pgprot_t prot)
> >   	return __pgprot(pgprot_val(prot) & ~PTE_TABLE_BIT);
> >   }
> >
> > +#ifdef CONFIG_NUMA_BALANCING
> > +/*
> > + * See the comment in include/asm-generic/pgtable.h
> > + */
> > +static inline int pte_protnone(pte_t pte)
> > +{
> > +	return (pte_val(pte) & (PTE_VALID | PTE_PROT_NONE)) == PTE_PROT_NONE;
> > +}
> > +
> > +static inline int pmd_protnone(pmd_t pmd)
> > +{
> > +	return pte_protnone(pmd_pte(pmd));
> > +}
> > +#endif
>
> Can these not be macros, like our other pte_* and pmd_* predicates in
> this header file?

They probably could be.  However there is precedence for the static 
inline form:

$ git grep pte_protnone | grep '\.h' | grep -v return
arch/arm64/include/asm/pgtable.h:static inline int pte_protnone(pte_t pte)
arch/powerpc/include/asm/book3s/64/hash.h:static inline int 
pte_protnone(pte_t pte)
arch/powerpc/include/asm/nohash/pgtable.h:static inline int 
pte_protnone(pte_t pte)
arch/s390/include/asm/pgtable.h:static inline int pte_protnone(pte_t pte)
arch/x86/include/asm/pgtable.h:static inline int pte_protnone(pte_t pte)
include/asm-generic/pgtable.h:static inline int pte_protnone(pte_t pte)


Actually I am a little surprised that all the arm64 pte_* and pmd_* 
things are not written as static inline to achieve added type safety. 
The generated code should be identical.


> Will