On a 16-socket 192-core POWER8 system, a context switching benchmark with as many software threads as CPUs (so each switch will go in and out of idle), upstream can achieve a rate of about 1 million context switches per second, due to contention on the mm refcount. powerpc/64s meets the prerequisites for CONFIG_MMU_LAZY_TLB_SHOOTDOWN, so enable the option. This increases the above benchmark to 118 million. Signed-off-by: Nicholas Piggin <npiggin@xxxxxxxxx> --- arch/powerpc/Kconfig | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index ba5b66189358..8a584414ef67 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -249,6 +249,7 @@ config PPC select IRQ_FORCED_THREADING select MMU_GATHER_PAGE_SIZE select MMU_GATHER_RCU_TABLE_FREE + select MMU_LAZY_TLB_SHOOTDOWN if PPC_BOOK3S_64 select MODULES_USE_ELF_RELA select NEED_DMA_MAP_STATE if PPC64 || NOT_COHERENT_CACHE select NEED_SG_DMA_LENGTH -- 2.23.0
