On Wed, Oct 02, 2019 at 10:33:24PM -0300, Leonardo Bras wrote: > Adds config option LOCKLESS_PAGE_TABLE_WALK_TRACKING to make possible > enabling tracking lockless pagetable walks directly from kernel config. > > Signed-off-by: Leonardo Bras <leonardo@xxxxxxxxxxxxx> > --- > mm/Kconfig | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/mm/Kconfig b/mm/Kconfig > index a5dae9a7eb51..00f487a0122f 100644 > --- a/mm/Kconfig > +++ b/mm/Kconfig > @@ -736,4 +736,15 @@ config ARCH_HAS_PTE_SPECIAL > config ARCH_HAS_HUGEPD > bool > > +config LOCKLESS_PAGE_TABLE_WALK_TRACKING > + bool "Track (and optimize) lockless page table walks" > + default n > + > + help > + Maintain a reference count of active lockless page table > + walkers. This adds 4 bytes to struct mm size, and two atomic > + operations to calls such as get_user_pages_fast(). Some > + architectures can optimize lockless page table operations if > + this is enabled. This shouldn't be a user visible option at all. Either the arch needs it and selects it or not.
