sparse irq_desc[] array: core kernel and x86 changes
Impact: new feature
Problem on distro kernels: irq_desc[NR_IRQS] takes megabytes of RAM with
NR_CPUS set to large values. The goal is to be able to scale up to much
larger NR_IRQS value without impacting the (important) common case.
To solve this, we generalize irq_desc[NR_IRQS] to an (optional) array of
irq_desc pointers.
When CONFIG_SPARSE_IRQ=y is used, we use kzalloc_node to get irq_desc,
this also makes the IRQ descriptors NUMA-local (to the site that calls
request_irq()).
This gets rid of the irq_cfg[] static array on x86 as well: irq_cfg now
uses desc->chip_data for x86 to store irq_cfg.
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/drivers/char/random.c b/drivers/char/random.c
index 675076f..d26891b 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -558,23 +558,9 @@
unsigned dont_count_entropy:1;
};
-static struct timer_rand_state *irq_timer_state[NR_IRQS];
-
-static struct timer_rand_state *get_timer_rand_state(unsigned int irq)
-{
- if (irq >= nr_irqs)
- return NULL;
-
- return irq_timer_state[irq];
-}
-
-static void set_timer_rand_state(unsigned int irq, struct timer_rand_state *state)
-{
- if (irq >= nr_irqs)
- return;
-
- irq_timer_state[irq] = state;
-}
+#ifndef CONFIG_SPARSE_IRQ
+struct timer_rand_state *irq_timer_state[NR_IRQS];
+#endif
static struct timer_rand_state input_timer_state;
@@ -933,8 +919,10 @@
{
struct timer_rand_state *state;
+#ifndef CONFIG_SPARSE_IRQ
if (irq >= nr_irqs)
return;
+#endif
state = get_timer_rand_state(irq);
diff --git a/drivers/pci/intr_remapping.c b/drivers/pci/intr_remapping.c
index 2de5a32..c9958ec 100644
--- a/drivers/pci/intr_remapping.c
+++ b/drivers/pci/intr_remapping.c
@@ -19,17 +19,75 @@
u8 irte_mask;
};
-static struct irq_2_iommu irq_2_iommuX[NR_IRQS];
+#ifdef CONFIG_SPARSE_IRQ
+static struct irq_2_iommu *get_one_free_irq_2_iommu(int cpu)
+{
+ struct irq_2_iommu *iommu;
+ int node;
+
+ node = cpu_to_node(cpu);
+
+ iommu = kzalloc_node(sizeof(*iommu), GFP_ATOMIC, node);
+ printk(KERN_DEBUG "alloc irq_2_iommu on cpu %d node %d\n", cpu, node);
+
+ return iommu;
+}
static struct irq_2_iommu *irq_2_iommu(unsigned int irq)
{
- return (irq < nr_irqs) ? irq_2_iommuX + irq : NULL;
+ struct irq_desc *desc;
+
+ desc = irq_to_desc(irq);
+
+ if (WARN_ON_ONCE(!desc))
+ return NULL;
+
+ return desc->irq_2_iommu;
+}
+
+static struct irq_2_iommu *irq_2_iommu_alloc_cpu(unsigned int irq, int cpu)
+{
+ struct irq_desc *desc;
+ struct irq_2_iommu *irq_iommu;
+
+ /*
+ * alloc irq desc if not allocated already.
+ */
+ desc = irq_to_desc_alloc_cpu(irq, cpu);
+ if (!desc) {
+ printk(KERN_INFO "can not get irq_desc for %d\n", irq);
+ return NULL;
+ }
+
+ irq_iommu = desc->irq_2_iommu;
+
+ if (!irq_iommu)
+ desc->irq_2_iommu = get_one_free_irq_2_iommu(cpu);
+
+ return desc->irq_2_iommu;
}
static struct irq_2_iommu *irq_2_iommu_alloc(unsigned int irq)
{
+ return irq_2_iommu_alloc_cpu(irq, boot_cpu_id);
+}
+
+#else /* !CONFIG_SPARSE_IRQ */
+
+static struct irq_2_iommu irq_2_iommuX[NR_IRQS];
+
+static struct irq_2_iommu *irq_2_iommu(unsigned int irq)
+{
+ if (irq < nr_irqs)
+ return &irq_2_iommuX[irq];
+
+ return NULL;
+}
+static struct irq_2_iommu *irq_2_iommu_alloc(unsigned int irq)
+{
return irq_2_iommu(irq);
}
+#endif
static DEFINE_SPINLOCK(irq_2_ir_lock);
@@ -86,9 +144,11 @@
if (!count)
return -1;
+#ifndef CONFIG_SPARSE_IRQ
/* protect irq_2_iommu_alloc later */
if (irq >= nr_irqs)
return -1;
+#endif
/*
* start the IRTE search from index 0.
@@ -130,6 +190,12 @@
table->base[i].present = 1;
irq_iommu = irq_2_iommu_alloc(irq);
+ if (!irq_iommu) {
+ spin_unlock(&irq_2_ir_lock);
+ printk(KERN_ERR "can't allocate irq_2_iommu\n");
+ return -1;
+ }
+
irq_iommu->iommu = iommu;
irq_iommu->irte_index = index;
irq_iommu->sub_handle = 0;
@@ -177,6 +243,12 @@
irq_iommu = irq_2_iommu_alloc(irq);
+ if (!irq_iommu) {
+ spin_unlock(&irq_2_ir_lock);
+ printk(KERN_ERR "can't allocate irq_2_iommu\n");
+ return -1;
+ }
+
irq_iommu->iommu = iommu;
irq_iommu->irte_index = index;
irq_iommu->sub_handle = subhandle;
diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index 1e3b934..2924faa 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -141,8 +141,12 @@
int i;
/* By default all event channels notify CPU#0. */
- for_each_irq_desc(i, desc)
+ for_each_irq_desc(i, desc) {
+ if (!desc)
+ continue;
+
desc->affinity = cpumask_of_cpu(0);
+ }
#endif
memset(cpu_evtchn, 0, sizeof(cpu_evtchn));
@@ -231,7 +235,7 @@
int irq;
/* Only allocate from dynirq range */
- for_each_irq_nr(irq)
+ for (irq = 0; irq < nr_irqs; irq++)
if (irq_bindcount[irq] == 0)
break;
@@ -792,7 +796,7 @@
mask_evtchn(evtchn);
/* No IRQ <-> event-channel mappings. */
- for_each_irq_nr(irq)
+ for (irq = 0; irq < nr_irqs; irq++)
irq_info[irq].evtchn = 0; /* zap event-channel binding */
for (evtchn = 0; evtchn < NR_EVENT_CHANNELS; evtchn++)
@@ -824,7 +828,7 @@
mask_evtchn(i);
/* Dynamic IRQ space is currently unbound. Zero the refcnts. */
- for_each_irq_nr(i)
+ for (i = 0; i < nr_irqs; i++)
irq_bindcount[i] = 0;
irq_ctx_init(smp_processor_id());