diff options
Diffstat (limited to 'arch/Kconfig')
| -rw-r--r-- | arch/Kconfig | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/arch/Kconfig b/arch/Kconfig index e3511afbb7f2..643f8a04141e 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -465,6 +465,23 @@ config ARCH_WANT_IRQS_OFF_ACTIVATE_MM irqs disabled over activate_mm. Architectures that do IPI based TLB shootdowns should enable this. +# Use normal mm refcounting for MMU_LAZY_TLB kernel thread references. +# MMU_LAZY_TLB_REFCOUNT=n can improve the scalability of context switching +# to/from kernel threads when the same mm is running on a lot of CPUs (a large +# multi-threaded application), by reducing contention on the mm refcount. +# +# This can be disabled if the architecture ensures no CPUs are using an mm as a +# "lazy tlb" beyond its final refcount (i.e., by the time __mmdrop frees the mm +# or its kernel page tables). This could be arranged by arch_exit_mmap(), or +# final exit(2) TLB flush, for example. +# +# To implement this, an arch *must*: +# Ensure the _lazy_tlb variants of mmgrab/mmdrop are used when manipulating +# the lazy tlb reference of a kthread's ->active_mm (non-arch code has been +# converted already). +config MMU_LAZY_TLB_REFCOUNT + def_bool y + config ARCH_HAVE_NMI_SAFE_CMPXCHG bool |