From 567f3e422a9a155d7c7643148efb5bf959065d34 Mon Sep 17 00:00:00 2001 From: Andrew Morton Date: Tue, 17 Jul 2007 04:03:58 -0700 Subject: [PATCH] x86_64: speedup touch_nmi_watchdog Avoid dirtying remote cpu's memory if it already has the correct value. Cc: Andi Kleen Cc: Konrad Rzeszutek Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/x86_64/kernel/nmi.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/arch/x86_64/kernel/nmi.c b/arch/x86_64/kernel/nmi.c index 931c64bad5e6..edbbc59b7523 100644 --- a/arch/x86_64/kernel/nmi.c +++ b/arch/x86_64/kernel/nmi.c @@ -296,7 +296,7 @@ static DEFINE_PER_CPU(unsigned, last_irq_sum); static DEFINE_PER_CPU(local_t, alert_counter); static DEFINE_PER_CPU(int, nmi_touch); -void touch_nmi_watchdog (void) +void touch_nmi_watchdog(void) { if (nmi_watchdog > 0) { unsigned cpu; @@ -306,8 +306,10 @@ void touch_nmi_watchdog (void) * do it ourselves because the alert count increase is not * atomic. */ - for_each_present_cpu (cpu) - per_cpu(nmi_touch, cpu) = 1; + for_each_present_cpu(cpu) { + if (per_cpu(nmi_touch, cpu) != 1) + per_cpu(nmi_touch, cpu) = 1; + } } touch_softlockup_watchdog(); -- 2.25.1