Re: [PATCH 0/3] NUMA boot hash allocation interleaving

From: Andi Kleen
Date: Wed Dec 15 2004 - 02:19:29 EST

On Tue, Dec 14, 2004 at 11:14:46PM -0800, Martin J. Bligh wrote:
> Well hold on a sec. We don't need to use the hugepages pool for this,
> do we? This is the same as using huge page mappings for the whole of
> kernel space on ia32. As long as it's a kernel mapping, and 16MB aligned
> and contig, we get it for free, surely?

The whole point of the patch is to not use the direct mapping, but
use a different interleaved mapping on NUMA machines to spread
the memory out over multiple nodes.

> > Using other page sizes would be probably tricky because the
> > linux VM can currently barely deal with two page sizes.
> > I suspect handling more would need some VM infrastructure effort
> > at least in the changed port.
> For the general case I'd agree. But this is a setup-time only tweak
> of the static kernel mapping, isn't it?

It's probably not impossible, just lots of ugly special cases.
e.g. how about supporting it for /proc/kcore etc?


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