x86: remove irqbalance in kernel for 32 bit

This has been deprecated for years, the user space irqbalanced utility
works better with numa, has configurable policies, etc...
Signed-off-by: Yinghai Lu <yhlu.kernel@gmai.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/Kconfig

@@ -1254,14 +1254,6 @@ config EFI
   	resultant kernel should continue to boot on existing non-EFI
   	platforms.
 
-config IRQBALANCE
-	def_bool y
-	prompt "Enable kernel irq balancing"
-	depends on X86_32 && SMP && X86_IO_APIC
-	help
-	  The default yes will allow the kernel to do irq load balancing.
-	  Saying no will keep the kernel from doing irq load balancing.
-
 config SECCOMP
 	def_bool y
 	prompt "Enable seccomp to safely compute untrusted bytecode"

arch/x86/configs/i386_defconfig

@@ -287,7 +287,6 @@ CONFIG_MTRR=y
 # CONFIG_MTRR_SANITIZER is not set
 CONFIG_X86_PAT=y
 CONFIG_EFI=y
-# CONFIG_IRQBALANCE is not set
 CONFIG_SECCOMP=y
 # CONFIG_HZ_100 is not set
 # CONFIG_HZ_250 is not set

arch/x86/kernel/io_apic_32.c

@@ -371,408 +371,6 @@ static void set_ioapic_affinity_irq(unsigned int irq, cpumask_t cpumask)
 	spin_unlock_irqrestore(&ioapic_lock, flags);
 }
 
-#if defined(CONFIG_IRQBALANCE)
-# include <asm/processor.h>	/* kernel_thread() */
-# include <linux/kernel_stat.h>	/* kstat */
-# include <linux/slab.h>		/* kmalloc() */
-# include <linux/timer.h>
-
-#define IRQBALANCE_CHECK_ARCH -999
-#define MAX_BALANCED_IRQ_INTERVAL	(5*HZ)
-#define MIN_BALANCED_IRQ_INTERVAL	(HZ/2)
-#define BALANCED_IRQ_MORE_DELTA		(HZ/10)
-#define BALANCED_IRQ_LESS_DELTA		(HZ)
-
-static int irqbalance_disabled __read_mostly = IRQBALANCE_CHECK_ARCH;
-static int physical_balance __read_mostly;
-static long balanced_irq_interval __read_mostly = MAX_BALANCED_IRQ_INTERVAL;
-
-static struct irq_cpu_info {
-	unsigned long *last_irq;
-	unsigned long *irq_delta;
-	unsigned long irq;
-} irq_cpu_data[NR_CPUS];
-
-#define CPU_IRQ(cpu)		(irq_cpu_data[cpu].irq)
-#define LAST_CPU_IRQ(cpu, irq)   (irq_cpu_data[cpu].last_irq[irq])
-#define IRQ_DELTA(cpu, irq) 	(irq_cpu_data[cpu].irq_delta[irq])
-
-#define IDLE_ENOUGH(cpu,now) \
-	(idle_cpu(cpu) && ((now) - per_cpu(irq_stat, (cpu)).idle_timestamp > 1))
-
-#define IRQ_ALLOWED(cpu, allowed_mask)	cpu_isset(cpu, allowed_mask)
-
-#define CPU_TO_PACKAGEINDEX(i) (first_cpu(per_cpu(cpu_sibling_map, i)))
-
-static cpumask_t balance_irq_affinity_init __initdata = CPU_MASK_ALL;
-
-static cpumask_t *balance_irq_affinity;
-
-
-static void __init irq_affinity_init_work(void *data)
-{
-	struct dyn_array *da = data;
-
-	int i;
-	struct  balance_irq_affinity *affinity;
-
-	affinity = *da->name;
-
-	for (i = 0; i < *da->nr; i++)
-		memcpy(&affinity[i], &balance_irq_affinity_init,
-			 sizeof(struct balance_irq_affinity));
-
-}
-
-DEFINE_DYN_ARRAY(balance_irq_affinity, sizeof(struct balance_irq_affinity), nr_irqs, PAGE_SIZE, irq_affinity_init_work);
-
-
-void set_balance_irq_affinity(unsigned int irq, cpumask_t mask)
-{
-	balance_irq_affinity[irq] = mask;
-}
-
-static unsigned long move(int curr_cpu, cpumask_t 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 >= NR_CPUS)
-				cpu = 0;
-		} else {
-			cpu--;
-			if (cpu == -1)
-				cpu = NR_CPUS-1;
-		}
-	} while (!cpu_online(cpu) || !IRQ_ALLOWED(cpu, allowed_mask) ||
-			(search_idle && !IDLE_ENOUGH(cpu, now)));
-
-	return cpu;
-}
-
-static inline void balance_irq(int cpu, int irq)
-{
-	unsigned long now = jiffies;
-	cpumask_t allowed_mask;
-	unsigned int new_cpu;
-
-	if (irqbalance_disabled)
-		return;
-
-	cpus_and(allowed_mask, cpu_online_map, balance_irq_affinity[irq]);
-	new_cpu = move(cpu, allowed_mask, now, 1);
-	if (cpu != new_cpu)
-		set_pending_irq(irq, cpumask_of_cpu(new_cpu));
-}
-
-static inline void rotate_irqs_among_cpus(unsigned long useful_load_threshold)
-{
-	int i, j;
-	struct irq_desc *desc;
-
-	for_each_online_cpu(i) {
-		for (j = 0; j < nr_irqs; j++) {
-			desc = irq_to_desc(j);
-			if (!desc->action)
-				continue;
-			/* Is it a significant load ?  */
-			if (IRQ_DELTA(CPU_TO_PACKAGEINDEX(i), j) <
-						useful_load_threshold)
-				continue;
-			balance_irq(i, j);
-		}
-	}
-	balanced_irq_interval = max((long)MIN_BALANCED_IRQ_INTERVAL,
-		balanced_irq_interval - BALANCED_IRQ_LESS_DELTA);
-	return;
-}
-
-static void do_irq_balance(void)
-{
-	int i, j;
-	unsigned long max_cpu_irq = 0, min_cpu_irq = (~0);
-	unsigned long move_this_load = 0;
-	int max_loaded = 0, min_loaded = 0;
-	int load;
-	unsigned long useful_load_threshold = balanced_irq_interval + 10;
-	int selected_irq;
-	int tmp_loaded, first_attempt = 1;
-	unsigned long tmp_cpu_irq;
-	unsigned long imbalance = 0;
-	cpumask_t allowed_mask, target_cpu_mask, tmp;
-	struct irq_desc *desc;
-
-	for_each_possible_cpu(i) {
-		int package_index;
-		CPU_IRQ(i) = 0;
-		if (!cpu_online(i))
-			continue;
-		package_index = CPU_TO_PACKAGEINDEX(i);
-		for (j = 0; j < nr_irqs; j++) {
-			unsigned long value_now, delta;
-			/* Is this an active IRQ or balancing disabled ? */
-			desc = irq_to_desc(j);
-			if (!desc->action || irq_balancing_disabled(j))
-				continue;
-			if (package_index == i)
-				IRQ_DELTA(package_index, j) = 0;
-			/* Determine the total count per processor per IRQ */
-			value_now = (unsigned long) kstat_irqs_cpu(j, i);
-
-			/* Determine the activity per processor per IRQ */
-			delta = value_now - LAST_CPU_IRQ(i, j);
-
-			/* Update last_cpu_irq[][] for the next time */
-			LAST_CPU_IRQ(i, j) = value_now;
-
-			/* Ignore IRQs whose rate is less than the clock */
-			if (delta < useful_load_threshold)
-				continue;
-			/* update the load for the processor or package total */
-			IRQ_DELTA(package_index, j) += delta;
-
-			/* Keep track of the higher numbered sibling as well */
-			if (i != package_index)
-				CPU_IRQ(i) += delta;
-			/*
-			 * We have sibling A and sibling B in the package
-			 *
-			 * cpu_irq[A] = load for cpu A + load for cpu B
-			 * cpu_irq[B] = load for cpu B
-			 */
-			CPU_IRQ(package_index) += delta;
-		}
-	}
-	/* Find the least loaded processor package */
-	for_each_online_cpu(i) {
-		if (i != CPU_TO_PACKAGEINDEX(i))
-			continue;
-		if (min_cpu_irq > CPU_IRQ(i)) {
-			min_cpu_irq = CPU_IRQ(i);
-			min_loaded = i;
-		}
-	}
-	max_cpu_irq = ULONG_MAX;
-
-tryanothercpu:
-	/*
-	 * Look for heaviest loaded processor.
-	 * We may come back to get the next heaviest loaded processor.
-	 * Skip processors with trivial loads.
-	 */
-	tmp_cpu_irq = 0;
-	tmp_loaded = -1;
-	for_each_online_cpu(i) {
-		if (i != CPU_TO_PACKAGEINDEX(i))
-			continue;
-		if (max_cpu_irq <= CPU_IRQ(i))
-			continue;
-		if (tmp_cpu_irq < CPU_IRQ(i)) {
-			tmp_cpu_irq = CPU_IRQ(i);
-			tmp_loaded = i;
-		}
-	}
-
-	if (tmp_loaded == -1) {
-	 /*
-	  * In the case of small number of heavy interrupt sources,
-	  * loading some of the cpus too much. We use Ingo's original
-	  * approach to rotate them around.
-	  */
-		if (!first_attempt && imbalance >= useful_load_threshold) {
-			rotate_irqs_among_cpus(useful_load_threshold);
-			return;
-		}
-		goto not_worth_the_effort;
-	}
-
-	first_attempt = 0;		/* heaviest search */
-	max_cpu_irq = tmp_cpu_irq;	/* load */
-	max_loaded = tmp_loaded;	/* processor */
-	imbalance = (max_cpu_irq - min_cpu_irq) / 2;
-
-	/*
-	 * if imbalance is less than approx 10% of max load, then
-	 * observe diminishing returns action. - quit
-	 */
-	if (imbalance < (max_cpu_irq >> 3))
-		goto not_worth_the_effort;
-
-tryanotherirq:
-	/* if we select an IRQ to move that can't go where we want, then
-	 * see if there is another one to try.
-	 */
-	move_this_load = 0;
-	selected_irq = -1;
-	for (j = 0; j < nr_irqs; j++) {
-		/* Is this an active IRQ? */
-		desc = irq_to_desc(j);
-		if (!desc->action)
-			continue;
-		if (imbalance <= IRQ_DELTA(max_loaded, j))
-			continue;
-		/* Try to find the IRQ that is closest to the imbalance
-		 * without going over.
-		 */
-		if (move_this_load < IRQ_DELTA(max_loaded, j)) {
-			move_this_load = IRQ_DELTA(max_loaded, j);
-			selected_irq = j;
-		}
-	}
-	if (selected_irq == -1)
-		goto tryanothercpu;
-
-	imbalance = move_this_load;
-
-	/* For physical_balance case, we accumulated both load
-	 * values in the one of the siblings cpu_irq[],
-	 * to use the same code for physical and logical processors
-	 * as much as possible.
-	 *
-	 * NOTE: the cpu_irq[] array holds the sum of the load for
-	 * sibling A and sibling B in the slot for the lowest numbered
-	 * sibling (A), _AND_ the load for sibling B in the slot for
-	 * the higher numbered sibling.
-	 *
-	 * We seek the least loaded sibling by making the comparison
-	 * (A+B)/2 vs B
-	 */
-	load = CPU_IRQ(min_loaded) >> 1;
-	for_each_cpu_mask(j, per_cpu(cpu_sibling_map, min_loaded)) {
-		if (load > CPU_IRQ(j)) {
-			/* This won't change cpu_sibling_map[min_loaded] */
-			load = CPU_IRQ(j);
-			min_loaded = j;
-		}
-	}
-
-	cpus_and(allowed_mask,
-		cpu_online_map,
-		balance_irq_affinity[selected_irq]);
-	target_cpu_mask = cpumask_of_cpu(min_loaded);
-	cpus_and(tmp, target_cpu_mask, allowed_mask);
-
-	if (!cpus_empty(tmp)) {
-		/* mark for change destination */
-		set_pending_irq(selected_irq, cpumask_of_cpu(min_loaded));
-
-		/* Since we made a change, come back sooner to
-		 * check for more variation.
-		 */
-		balanced_irq_interval = max((long)MIN_BALANCED_IRQ_INTERVAL,
-			balanced_irq_interval - BALANCED_IRQ_LESS_DELTA);
-		return;
-	}
-	goto tryanotherirq;
-
-not_worth_the_effort:
-	/*
-	 * if we did not find an IRQ to move, then adjust the time interval
-	 * upward
-	 */
-	balanced_irq_interval = min((long)MAX_BALANCED_IRQ_INTERVAL,
-		balanced_irq_interval + BALANCED_IRQ_MORE_DELTA);
-	return;
-}
-
-static int balanced_irq(void *unused)
-{
-	int i;
-	unsigned long prev_balance_time = jiffies;
-	long time_remaining = balanced_irq_interval;
-	struct irq_desc *desc;
-
-	/* push everything to CPU 0 to give us a starting point.  */
-	for (i = 0 ; i < nr_irqs ; i++) {
-		desc = irq_to_desc(i);
-		desc->pending_mask = cpumask_of_cpu(0);
-		set_pending_irq(i, cpumask_of_cpu(0));
-	}
-
-	set_freezable();
-	for ( ; ; ) {
-		time_remaining = schedule_timeout_interruptible(time_remaining);
-		try_to_freeze();
-		if (time_after(jiffies,
-				prev_balance_time+balanced_irq_interval)) {
-			preempt_disable();
-			do_irq_balance();
-			prev_balance_time = jiffies;
-			time_remaining = balanced_irq_interval;
-			preempt_enable();
-		}
-	}
-	return 0;
-}
-
-static int __init balanced_irq_init(void)
-{
-	int i;
-	struct cpuinfo_x86 *c;
-	cpumask_t tmp;
-
-	cpus_shift_right(tmp, cpu_online_map, 2);
-	c = &boot_cpu_data;
-	/* When not overwritten by the command line ask subarchitecture. */
-	if (irqbalance_disabled == IRQBALANCE_CHECK_ARCH)
-		irqbalance_disabled = NO_BALANCE_IRQ;
-	if (irqbalance_disabled)
-		return 0;
-
-	 /* disable irqbalance completely if there is only one processor online */
-	if (num_online_cpus() < 2) {
-		irqbalance_disabled = 1;
-		return 0;
-	}
-	/*
-	 * Enable physical balance only if more than 1 physical processor
-	 * is present
-	 */
-	if (smp_num_siblings > 1 && !cpus_empty(tmp))
-		physical_balance = 1;
-
-	for_each_online_cpu(i) {
-		irq_cpu_data[i].irq_delta = kzalloc(sizeof(unsigned long) * nr_irqs, GFP_KERNEL);
-		irq_cpu_data[i].last_irq = kzalloc(sizeof(unsigned long) * nr_irqs, GFP_KERNEL);
-		if (irq_cpu_data[i].irq_delta == NULL || irq_cpu_data[i].last_irq == NULL) {
-			printk(KERN_ERR "balanced_irq_init: out of memory");
-			goto failed;
-		}
-	}
-
-	printk(KERN_INFO "Starting balanced_irq\n");
-	if (!IS_ERR(kthread_run(balanced_irq, NULL, "kirqd")))
-		return 0;
-	printk(KERN_ERR "balanced_irq_init: failed to spawn balanced_irq");
-failed:
-	for_each_possible_cpu(i) {
-		kfree(irq_cpu_data[i].irq_delta);
-		irq_cpu_data[i].irq_delta = NULL;
-		kfree(irq_cpu_data[i].last_irq);
-		irq_cpu_data[i].last_irq = NULL;
-	}
-	return 0;
-}
-
-int __devinit irqbalance_disable(char *str)
-{
-	irqbalance_disabled = 1;
-	return 1;
-}
-
-__setup("noirqbalance", irqbalance_disable);
-
-late_initcall(balanced_irq_init);
-#endif /* CONFIG_IRQBALANCE */
 #endif /* CONFIG_SMP */
 
 #ifndef CONFIG_SMP

arch/x86/kernel/quirks.c

@@ -35,9 +35,6 @@ static void __devinit quirk_intel_irqbalance(struct pci_dev *dev)
 	if (!(word & (1 << 13))) {
 		dev_info(&dev->dev, "Intel E7520/7320/7525 detected; "
 			"disabling irq balancing and affinity\n");
-#ifdef CONFIG_IRQBALANCE
-		irqbalance_disable("");
-#endif
 		noirqdebug_setup("");
 #ifdef CONFIG_PROC_FS
 		no_irq_affinity = 1;

include/linux/irq.h

@@ -185,7 +185,7 @@ struct irq_desc {
 	cpumask_t		affinity;
 	unsigned int		cpu;
 #endif
-#if defined(CONFIG_GENERIC_PENDING_IRQ) || defined(CONFIG_IRQBALANCE)
+#ifdef CONFIG_GENERIC_PENDING_IRQ
 	cpumask_t		pending_mask;
 #endif
 #ifdef CONFIG_PROC_FS
@@ -241,13 +241,13 @@ extern int setup_irq(unsigned int irq, struct irqaction *new);
 
 #ifdef CONFIG_SMP
 
-#if defined(CONFIG_GENERIC_PENDING_IRQ) || defined(CONFIG_IRQBALANCE)
+#ifdef CONFIG_GENERIC_PENDING_IRQ
 
 void set_pending_irq(unsigned int irq, cpumask_t mask);
 void move_native_irq(int irq);
 void move_masked_irq(int irq);
 
-#else /* CONFIG_GENERIC_PENDING_IRQ || CONFIG_IRQBALANCE */
+#else /* CONFIG_GENERIC_PENDING_IRQ */
 
 static inline void move_irq(int irq)
 {
@@ -274,14 +274,6 @@ static inline void set_pending_irq(unsigned int irq, cpumask_t mask)
 
 #endif /* CONFIG_SMP */
 
-#ifdef CONFIG_IRQBALANCE
-extern void set_balance_irq_affinity(unsigned int irq, cpumask_t mask);
-#else
-static inline void set_balance_irq_affinity(unsigned int irq, cpumask_t mask)
-{
-}
-#endif
-
 extern int no_irq_affinity;
 
 static inline int irq_balancing_disabled(unsigned int irq)

kernel/irq/manage.c

@@ -86,8 +86,6 @@ int irq_set_affinity(unsigned int irq, cpumask_t cpumask)
 	if (!desc->chip->set_affinity)
 		return -EINVAL;
 
-	set_balance_irq_affinity(irq, cpumask);
-
 #ifdef CONFIG_GENERIC_PENDING_IRQ
 	if (desc->status & IRQ_MOVE_PCNTXT) {
 		unsigned long flags;
@@ -122,7 +120,6 @@ int irq_select_affinity(unsigned int irq)
 	desc->affinity = mask;
 	desc->chip->set_affinity(irq, mask);
 
-	set_balance_irq_affinity(irq, mask);
 	return 0;
 }
 #endif