[PATCH 4/4] kstat: modify kstat_irqs_legacy to be variable sized

Mike Travis
2009-01-10T22:38:41Z

[-- Attachment #1: var-kstat-irqs --]
[-- Type: text/plain, Size: 1338 bytes --]

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>
---
kernel/irq/handle.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

--- linux-2.6-for-ingo.orig/kernel/irq/handle.c
+++ linux-2.6-for-ingo/kernel/irq/handle.c
@@ -124,8 +124,7 @@ static struct irq_desc irq_desc_legacy[N
}
};

-/* 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)
{
@@ -146,9 +145,13 @@ 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 */
+ 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_IRQS_LEGACY;
lockdep_set_class(&desc[i].lock, &irq_desc_lock_class);
init_alloc_desc_masks(&desc[i], 0, true);
irq_desc_ptrs[i] = desc + i;

--