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

Mike Travis
2009-01-11T17:50:29Z

Ingo Molnar wrote:
> * Yinghai Lu <yinghai@kernel.org> 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;
>
> indeed - i fixed this in tip/cpus4096.
>
> Ingo

Ahh, I didn't see this. Thanks Ingo!