[PATCH] move apic_timer_irqs to irqstat

This patch from Ravikiran G Thirumalai removes
cacheline bouncing of apic_timer_irqs

arch/i386/kernel/apic.c

@@ -1057,7 +1057,6 @@ inline void smp_local_timer_interrupt(struct pt_regs * regs)
  * [ if a single-CPU system runs an SMP kernel then we call the local
  *   interrupt as well. Thus we cannot inline the local irq ... ]
  */
-unsigned int apic_timer_irqs [NR_CPUS];
 
 void smp_apic_timer_interrupt(struct pt_regs regs)
 {
@@ -1066,7 +1065,7 @@ void smp_apic_timer_interrupt(struct pt_regs regs)
 	/*
 	 * the NMI deadlock-detector uses this.
 	 */
-	apic_timer_irqs[cpu]++;
+	irq_stat[cpu].apic_timer_irqs++;
 
 	/*
 	 * NOTE! We'd better ACK the irq immediately,

arch/i386/kernel/irq.c

@@ -171,7 +171,7 @@ int show_interrupts(struct seq_file *p, void *v)
 	seq_printf(p, "LOC: ");
 	for (j = 0; j < NR_CPUS; j++)
 		if (cpu_online(j))
-			p += seq_printf(p, "%10u ", apic_timer_irqs[j]);
+			p += seq_printf(p, "%10u ", irq_stat[j].apic_timer_irqs);
 	seq_putc(p, '\n');
 #endif
 	seq_printf(p, "ERR: %10u\n", atomic_read(&irq_err_count));

arch/i386/kernel/nmi.c

@@ -348,7 +348,7 @@ void nmi_watchdog_tick (struct pt_regs * regs)
 	 */
 	int sum, cpu = smp_processor_id();
 
-	sum = apic_timer_irqs[cpu];
+	sum = irq_stat[cpu].apic_timer_irqs;
 
 	if (last_irq_sums[cpu] == sum) {
 		/*

include/asm-i386/apic.h

@@ -87,7 +87,6 @@ extern void enable_APIC_timer(void);
 extern struct pm_dev *apic_pm_register(pm_dev_t, unsigned long, pm_callback);
 extern void apic_pm_unregister(struct pm_dev*);
 
-extern unsigned int apic_timer_irqs [NR_CPUS];
 extern int check_nmi_watchdog (void);
 extern void enable_NMI_through_LVT0 (void * dummy);
 

include/asm-i386/hardirq.h

@@ -12,6 +12,7 @@ typedef struct {
 	struct task_struct * __ksoftirqd_task; /* waitqueue is too large */
 	unsigned long idle_timestamp;
 	unsigned int __nmi_count;	/* arch dependent */
+	unsigned int apic_timer_irqs;	/* arch dependent */
 } ____cacheline_aligned irq_cpustat_t;
 
 #include <linux/irq_cpustat.h>	/* Standard mappings for irq_cpustat_t above */

kernel/softirq.c

@@ -31,7 +31,7 @@
    - Tasklets: serialized wrt itself.
  */
 
-irq_cpustat_t irq_stat[NR_CPUS];
+irq_cpustat_t irq_stat[NR_CPUS] ____cacheline_aligned;
 
 static struct softirq_action softirq_vec[32] __cacheline_aligned_in_smp;