Re: [PATCH] irq: Add node_affinity CPU masks for smarter irqbalance hints

[Yong Zhang]

On Mon, Nov 23, 2009 at 2:46 PM, Peter P Waskiewicz Jr
<peter.p.waskiewicz.jr@xxxxxxxxx> wrote:
> This patchset adds a new CPU mask for SMP systems to the irq_desc
> struct. ÂIt also exposes an API for underlying device drivers to
> assist irqbalance in making smarter decisions when balancing, especially
> in a NUMA environment. ÂFor example, an ethernet driver with MSI-X may
> wish to limit the CPUs that an interrupt can be balanced within to
> stay on a single NUMA node. ÂCurrent irqbalance operation can move the
> interrupt off the node, resulting in cross-node memory accesses and
> locks.
>
> The API is a get/set API within the kernel, along with a /proc entry
> for the interrupt.
>
> Signed-off-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@xxxxxxxxx>
> ---

1) I think you should consider CONFIG_CPUMASK_OFFSTACK which will affect
   node_affinity.
2) It seems like this patch can't work with SPARSE_IRQ.

Thanks,
Yong
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