From 511ba86e1d386f671084b5d0e6f110bb30b8eeb2 Mon Sep 17 00:00:00 2001 From: Boris Ostrovsky Date: Sat, 23 Mar 2013 09:36:36 -0400 Subject: x86, mm: Patch out arch_flush_lazy_mmu_mode() when running on bare metal Invoking arch_flush_lazy_mmu_mode() results in calls to preempt_enable()/disable() which may have performance impact. Since lazy MMU is not used on bare metal we can patch away arch_flush_lazy_mmu_mode() so that it is never called in such environment. [ hpa: the previous patch "Fix vmalloc_fault oops during lazy MMU updates" may cause a minor performance regression on bare metal. This patch resolves that performance regression. It is somewhat unclear to me if this is a good -stable candidate. ] Signed-off-by: Boris Ostrovsky Link: http://lkml.kernel.org/r/1364045796-10720-2-git-send-email-konrad.wilk@oracle.com Tested-by: Josh Boyer Tested-by: Konrad Rzeszutek Wilk Acked-by: Borislav Petkov Signed-off-by: Konrad Rzeszutek Wilk Signed-off-by: H. Peter Anvin Cc: SEE NOTE ABOVE --- arch/x86/lguest/boot.c | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/x86/lguest') diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c index 1cbd89ca5569..7114c63f047d 100644 --- a/arch/x86/lguest/boot.c +++ b/arch/x86/lguest/boot.c @@ -1334,6 +1334,7 @@ __init void lguest_init(void) pv_mmu_ops.read_cr3 = lguest_read_cr3; pv_mmu_ops.lazy_mode.enter = paravirt_enter_lazy_mmu; pv_mmu_ops.lazy_mode.leave = lguest_leave_lazy_mmu_mode; + pv_mmu_ops.lazy_mode.flush = paravirt_flush_lazy_mmu; pv_mmu_ops.pte_update = lguest_pte_update; pv_mmu_ops.pte_update_defer = lguest_pte_update; -- cgit v1.2.3