[PATCH] mm: split page table lock

[deliverable/linux.git] / mm / Kconfig

diff --git a/mm/Kconfig b/mm/Kconfig
index 391ffc54d13675846cb61c5fc91a875914ac11a8..f35a550ba4b92f9749fee63d57e1f5708adc1dc6 100644 (file)
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -111,3 +111,16 @@ config SPARSEMEM_STATIC
 config SPARSEMEM_EXTREME
        def_bool y
        depends on SPARSEMEM && !SPARSEMEM_STATIC
+
+# Heavily threaded applications may benefit from splitting the mm-wide
+# page_table_lock, so that faults on different parts of the user address
+# space can be handled with less contention: split it at this NR_CPUS.
+# Default to 4 for wider testing, though 8 might be more appropriate.
+# ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock.
+# PA-RISC's debug spinlock_t is too large for the 32-bit struct page.
+#
+config SPLIT_PTLOCK_CPUS
+       int
+       default "4096" if ARM && !CPU_CACHE_VIPT
+       default "4096" if PARISC && DEBUG_SPINLOCK && !64BIT
+       default "4"