Re: [PATCH 05/17] asm-generic/tlb: Rename HAVE_RCU_TABLE_NO_INVALIDATE

[Aneesh Kumar K.V]

On 12/16/19 6:07 PM, Peter Zijlstra wrote:
> On Mon, Dec 16, 2019 at 06:01:58PM +0530, Aneesh Kumar K.V wrote:
> > Peter Zijlstra <peterz@xxxxxxxxxxxxx> writes:
> >
> > > Towards a more consistent naming scheme.
> > >
> > > Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> > > ---
> > >   arch/Kconfig              |    3 ++-
> > >   arch/powerpc/Kconfig      |    2 +-
> > >   arch/sparc/Kconfig        |    2 +-
> > >   include/asm-generic/tlb.h |    2 +-
> > >   mm/mmu_gather.c           |    2 +-
> > >   5 files changed, 6 insertions(+), 5 deletions(-)
> > >
> > > --- a/arch/Kconfig
> > > +++ b/arch/Kconfig
> > > @@ -396,8 +396,9 @@ config HAVE_ARCH_JUMP_LABEL_RELATIVE
> > >   config MMU_GATHER_RCU_TABLE_FREE
> > >   	bool
> > >   
> > > -config HAVE_RCU_TABLE_NO_INVALIDATE
> > > +config MMU_GATHER_NO_TABLE_INVALIDATE
> > >   	bool
> > > +	depends on MMU_GATHER_RCU_TABLE_FREE
> >
> >
> > Can we drop this Kernel config option instead use
> > MMU_GATHER_RCU_TABLE_FREE? IMHO reducing the kernel config related to
> > mmu_gather can reduce the complexity.
>
> I'm confused, are you saing you're happy to have PowerPC eat the extra
> TLB invalidates? I thought you cared about PPC performance :-)

Instead can we do

static inline void tlb_table_invalidate(struct mmu_gather *tlb)
{
#ifndef CONFIG_MMU_GATHER_RCU_TABLE_FREE
	 * Invalidate page-table caches used by hardware walkers. Then we still
	 * need to RCU-sched wait while freeing the pages because software
	 * walkers can still be in-flight.
	 */
	tlb_flush_mmu_tlbonly(tlb);
#endif
}

-aneesh