Re: [PATCH 0/8] Announcement: Enhanced NUMA scheduling with adaptiveaffinity

[Christoph Lameter]

On Mon, 12 Nov 2012, Peter Zijlstra wrote:

> The biggest conceptual addition, beyond the elimination of the home
> node, is that the scheduler is now able to recognize 'private' versus
> 'shared' pages, by carefully analyzing the pattern of how CPUs touch the
> working set pages. The scheduler automatically recognizes tasks that
> share memory with each other (and make dominant use of that memory) -
> versus tasks that allocate and use their working set privately.

That is a key distinction to make and if this really works then that is
major progress.

> This new scheduler code is then able to group tasks that are "memory
> related" via their memory access patterns together: in the NUMA context
> moving them on the same node if possible, and spreading them amongst
> nodes if they use private memory.

What happens if processes memory accesses  are related but the
common set of data does not fit into the memory provided by a single node?

The correct resolution usually is in that case to interleasve the pages
over both nodes in use.

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