kstat: modify kstat_irqs_legacy to be variable sized

Impact: reduce memory usage.

Allocate kstat_irqs_legacy based on nr_cpu_ids to deal with this
memory usage bump when NR_CPUS bumped from 128 to 4096:

     8192   +253952    262144 +3100%  kstat_irqs_legacy(.bss)

This is only when CONFIG_SPARSE_IRQS=y.

Signed-off-by: Mike Travis <travis@sgi.com>

diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
index ebba7a116f14d4ca2662220dbc8852b43698e3e0..b39f32ac8f80a9a1f39ded9e1e47d8215e88412f 100644 (file)
--- a/kernel/irq/handle.c
+++ b/kernel/irq/handle.c
@@ -124,8 +124,7 @@ static struct irq_desc irq_desc_legacy[NR_IRQS_LEGACY] __cacheline_aligned_in_sm
        }
 };
 
-/* FIXME: use bootmem alloc ...*/
-static unsigned int kstat_irqs_legacy[NR_IRQS_LEGACY][NR_CPUS];
+static unsigned int *kstat_irqs_legacy;
 
 int __init early_irq_init(void)
 {
@@ -144,9 +143,14 @@ int __init early_irq_init(void)
        /* allocate irq_desc_ptrs array based on nr_irqs */
        irq_desc_ptrs = alloc_bootmem(nr_irqs * sizeof(void *));
 
+       /* allocate based on nr_cpu_ids */
+       /* FIXME: invert kstat_irgs, and it'd be a per_cpu_alloc'd thing */
+       kstat_irqs_legacy = alloc_bootmem(NR_IRQS_LEGACY * nr_cpu_ids *
+                                         sizeof(int));
+
        for (i = 0; i < legacy_count; i++) {
                desc[i].irq = i;
-               desc[i].kstat_irqs = kstat_irqs_legacy[i];
+               desc[i].kstat_irqs = kstat_irqs_legacy + i * nr_cpu_ids;
                lockdep_set_class(&desc[i].lock, &irq_desc_lock_class);
                init_alloc_desc_masks(&desc[i], 0, true);
                irq_desc_ptrs[i] = desc + i;