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

Mike Travis
2009-01-11T17:41:16Z

Yinghai Lu wrote:
> On Sat, Jan 10, 2009 at 2:38 PM, Mike Travis <travis@sgi.com> wrote:
>> 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;
>
> here should be
>
> + desc[i].kstat_irqs = kstat_irqs_legacy + i * nr_cpu_ids;
>
> YH

Hmm, thanks! (I wonder why I wanted it the other way? Oh well.)

I'll make an append patch to fix it.

Thanks,
Mike