From: Andrew Morton <akpm@linux-foundation.org>
Date: Tue, 17 Jul 2007 11:03:57 +0000 (-0700)
Subject: i386: speedup touch_nmi_watchdog
X-Git-Tag: v2.6.23-rc1~706
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=f2890255b0ade497893d1e5e99f519b5c1d50f7d;p=platform%2Fkernel%2Flinux-3.10.git

i386: speedup touch_nmi_watchdog

Avoid dirtying remote cpu's memory if it already has the correct value.

Cc: Andi Kleen <ak@suse.de>
Cc: Konrad Rzeszutek <konrad@darnok.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/arch/i386/kernel/nmi.c b/arch/i386/kernel/nmi.c
index fba121f..03b7f55 100644
--- a/arch/i386/kernel/nmi.c
+++ b/arch/i386/kernel/nmi.c
@@ -295,7 +295,7 @@ static unsigned int
 	last_irq_sums [NR_CPUS],
 	alert_counter [NR_CPUS];
 
-void touch_nmi_watchdog (void)
+void touch_nmi_watchdog(void)
 {
 	if (nmi_watchdog > 0) {
 		unsigned cpu;
@@ -304,8 +304,10 @@ void touch_nmi_watchdog (void)
 		 * Just reset the alert counters, (other CPUs might be
 		 * spinning on locks we hold):
 		 */
-		for_each_present_cpu (cpu)
-			alert_counter[cpu] = 0;
+		for_each_present_cpu(cpu) {
+			if (alert_counter[cpu])
+				alert_counter[cpu] = 0;
+		}
 	}
 
 	/*