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authorAndrew Morton <akpm@linux-foundation.org>2007-07-17 04:03:58 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-07-17 10:23:04 -0700
commit567f3e422a9a155d7c7643148efb5bf959065d34 (patch)
tree2b9959e3328fd78c4fe1ef371f02604de97c39eb /arch/x86_64
parentf2890255b0ade497893d1e5e99f519b5c1d50f7d (diff)
downloadlinux-2.6.34-ux500-567f3e422a9a155d7c7643148efb5bf959065d34.tar.gz
x86_64: 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>
Diffstat (limited to 'arch/x86_64')
-rw-r--r--arch/x86_64/kernel/nmi.c8
1 files changed, 5 insertions, 3 deletions
diff --git a/arch/x86_64/kernel/nmi.c b/arch/x86_64/kernel/nmi.c
index 931c64bad5e..edbbc59b752 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();