ppc64: Add Ingo's irq affinity stuff, from x86

arch/ppc64/kernel/idle.c

@@ -84,6 +84,8 @@ int cpu_idle(void)
 	lpaca = get_paca();
 
 	while (1) {
+		irq_stat[smp_processor_id()].idle_timestamp = jiffies;
+
 		if (lpaca->xLpPaca.xSharedProc) {
 			if (ItLpQueue_isLpIntPending(lpaca->lpQueuePtr))
 				process_iSeries_events();
@@ -123,6 +125,7 @@ int cpu_idle(void)
 	long oldval;
 
 	while (1) {
+		irq_stat[smp_processor_id()].idle_timestamp = jiffies;
 		oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED);
 
 		if (!oldval) {

arch/ppc64/kernel/irq.c

@@ -410,6 +410,75 @@ handle_irq_event(int irq, struct pt_regs *regs, struct irqaction *action)
 	__cli();
 }
 
+#ifdef CONFIG_SMP
+extern unsigned int irq_affinity [NR_IRQS];
+
+typedef struct {
+	unsigned long cpu;
+	unsigned long timestamp;
+} ____cacheline_aligned irq_balance_t;
+
+static irq_balance_t irq_balance[NR_IRQS] __cacheline_aligned
+			= { [ 0 ... NR_IRQS-1 ] = { 1, 0 } };
+
+#define IDLE_ENOUGH(cpu,now) \
+		(idle_cpu(cpu) && ((now) - irq_stat[(cpu)].idle_timestamp > ((HZ/100)+1)))
+
+#define IRQ_ALLOWED(cpu,allowed_mask) \
+		((1 << cpu) & (allowed_mask))
+
+static unsigned long move(unsigned long curr_cpu, unsigned long allowed_mask,
+			  unsigned long now, int direction)
+{
+	int search_idle = 1;
+	int cpu = curr_cpu;
+
+	goto inside;
+
+	do {
+		if (unlikely(cpu == curr_cpu))
+			search_idle = 0;
+inside:
+		if (direction == 1) {
+			cpu++;
+			if (cpu >= smp_num_cpus)
+				cpu = 0;
+		} else {
+			cpu--;
+			if (cpu == -1)
+				cpu = smp_num_cpus-1;
+		}
+	} while (!IRQ_ALLOWED(cpu,allowed_mask) ||
+			(search_idle && !IDLE_ENOUGH(cpu,now)));
+
+	return cpu;
+}
+
+static inline void balance_irq(int irq)
+{
+	irq_balance_t *entry = irq_balance + irq;
+	unsigned long now = jiffies;
+
+	if (unlikely(entry->timestamp != now)) {
+		unsigned long allowed_mask;
+		unsigned long random_number;
+
+		if (!irq_desc[irq].handler->set_affinity)
+			return;
+
+		random_number = mftb();
+		random_number &= 1;
+
+		allowed_mask = cpu_online_map & irq_affinity[irq];
+		entry->timestamp = now;
+		entry->cpu = move(entry->cpu, allowed_mask, now, random_number);
+		irq_desc[irq].handler->set_affinity(irq, 1 << entry->cpu);
+	}
+}
+#else
+#define balance_irq(irq) do { } while (0)
+#endif
+
 /*
  * Eventually, this should take an array of interrupts and an array size
  * so it can dispatch multiple interrupts.
@@ -421,6 +490,8 @@ void ppc_irq_dispatch_handler(struct pt_regs *regs, int irq)
 	int cpu = smp_processor_id();
 	irq_desc_t *desc = irq_desc + irq;
 
+	balance_irq(irq);
+
 	kstat.irqs[cpu][irq]++;
 	spin_lock(&desc->lock);
 	ack_irq(irq);	

include/asm-ppc64/hardirq.h

@@ -26,7 +26,7 @@ typedef struct {
 #endif
 	unsigned int __local_bh_count;
 	unsigned int __syscall_count;
-	unsigned long __unused;
+	unsigned long idle_timestamp;
 	struct task_struct * __ksoftirqd_task;
 } ____cacheline_aligned irq_cpustat_t;