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SubjectRe: [PATCH] Use NUMA node cpu mask in irq affinity


On 02/08/2012 06:51 PM, Yinghai Lu wrote:
> On Wed, Feb 8, 2012 at 12:48 PM, Prarit Bhargava <prarit@redhat.com> wrote:
>> The irq affinity files (/proc/irq/.../smp_affinity) contain a mask that is used
>> to "pin" an irq to a set of cpus. On boot this set is currently all cpus.
>> This can be incorrect as ACPI SRAT may tell us that a specific device or
>> bus is attached to a particular node and it's cpus.
>>
>> When setting up the irq affinity we should take into account the NUMA node
>> cpu mask by and'ing it into the irq's affinity mask.
>>
>> Signed-off-by: Prarit Bhargava <prarit@redhat.com>
>> Acked-by: Neil Horman <nhorman@tuxdriver.com>
>> ---
>> kernel/irq/manage.c | 2 ++
>> 1 files changed, 2 insertions(+), 0 deletions(-)
>>
>> diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
>> index a9a9dbe..2fb3469 100644
>> --- a/kernel/irq/manage.c
>> +++ b/kernel/irq/manage.c
>> @@ -301,6 +301,8 @@ setup_affinity(unsigned int irq, struct irq_desc *desc, struct cpumask *mask)
>> }
>>
>> cpumask_and(mask, cpu_online_mask, set);
>> + if (desc->irq_data.node != -1)
>> + cpumask_and(mask, mask, cpumask_of_node(desc->irq_data.node));
>> ret = chip->irq_set_affinity(&desc->irq_data, mask, false);
>> switch (ret) {
>> case IRQ_SET_MASK_OK:
>> --
>
> How about all cpus on that node get offlined?

Good point. I guess that also goes to tglx's comments wondering what happens if the mask ends up being zero.

I'll think about that and send out a new patch shortly.

P.
>
> Yinghai


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