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Subject[rfc 33/45] x86_64: Use CPU ops for nmi alert counter
These are critical fast paths. Using a segment override instead of an address
calculation is reducing overhead.

Signed-off-by: Christoph LAmeter <clameter@sgi.com>
---
arch/x86/kernel/nmi_64.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

Index: linux-2.6/arch/x86/kernel/nmi_64.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/nmi_64.c 2007-11-19 15:38:59.522056618 -0800
+++ linux-2.6/arch/x86/kernel/nmi_64.c 2007-11-19 15:40:04.481556226 -0800
@@ -291,7 +291,7 @@ void stop_apic_nmi_watchdog(void *unused
*/

static DEFINE_PER_CPU(unsigned, last_irq_sum);
-static DEFINE_PER_CPU(local_t, alert_counter);
+static DEFINE_PER_CPU(int, alert_counter);
static DEFINE_PER_CPU(int, nmi_touch);

void touch_nmi_watchdog(void)
@@ -355,13 +355,13 @@ int __kprobes nmi_watchdog_tick(struct p
* Ayiee, looks like this CPU is stuck ...
* wait a few IRQs (5 seconds) before doing the oops ...
*/
- local_inc(&__get_cpu_var(alert_counter));
- if (local_read(&__get_cpu_var(alert_counter)) == 5*nmi_hz)
+ CPU_INC(get_cpu_var(alert_counter));
+ if (CPU_READ(get_cpu_var(alert_counter)) == 5*nmi_hz)
die_nmi("NMI Watchdog detected LOCKUP on CPU %d\n", regs,
panic_on_timeout);
} else {
__get_cpu_var(last_irq_sum) = sum;
- local_set(&__get_cpu_var(alert_counter), 0);
+ CPU_WRITE(get_cpu_var(alert_counter), 0);
}

/* see if the nmi watchdog went off */
--
-
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