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

[Peter Zijlstra <peterz@infradead.org>]

On Mon, 2009-11-23 at 01:36 -0800, Peter P Waskiewicz Jr wrote:

> This mechanism isn't going to be used by any internal kernel mechanism
> for determining interrupt placement or operation.  It's purely something
> that either a driver can modify, or external script (through /proc),
> that irqbalance will make use of.  If irqbalance isn't running, or the
> current version of irqbalance doesn't support reading node_affinity,
> then it won't affect the system's operation.
> 
> If irqbalance does support it, it'll read whatever the supplied mask is,
> and then will try and balance interrupts within that mask.  It will bail
> if the mask is invalid, or won't apply to the running system, just like
> how putting a bogus mask into smp_affinity is ignored.
> 
> If there's something I'm missing beyond this with the two suggestions
> you've made (I looked into those two parameters and tried to draw
> conclusions), please let me know.

I don't see the point in adding it, if the driver wants to set a node
cpu mask it can already do that using the regular smp affinity settings.

Same for userspace.