Re: [PATCH] mm: add node physical memory range to sysfs

From: Davidlohr Bueso
Date: Wed Dec 12 2012 - 21:03:31 EST


On Wed, 2012-12-12 at 17:48 -0800, Dave Hansen wrote:
> On 12/12/2012 05:18 PM, Davidlohr Bueso wrote:
> > On Fri, 2012-12-07 at 16:17 -0800, Dave Hansen wrote:
> >> Seems like the better way to do this would be to expose the DIMMs
> >> themselves in some way, and then map _those_ back to a node.
> >
> > Good point, and from a DIMM perspective, I agree, and will look into
> > this. However, IMHO, having the range of physical addresses for every
> > node still provides valuable information, from a NUMA point of view. For
> > example, dealing with node related e820 mappings.
>
> But if we went and did it per-DIMM (showing which physical addresses and
> NUMA nodes a DIMM maps to), wouldn't that be redundant with this
> proposed interface?
>

If DIMMs overlap between nodes, then we wouldn't have an exact range for
a node in question. Having both approaches would complement each other.

> How do you plan to use this in practice, btw?
>

It started because I needed to recognize the address of a node to remove
it from the e820 mappings and have the system "ignore" the node's
memory.

Thanks,
Davidlohr

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