On Fri, 29 Jun 2012, Johannes Weiner wrote:

On Fri, Jun 29, 2012 at 01:49:52PM +0200, Petr Holasek wrote:

quoted

Introduces new sysfs boolean knob /sys/kernel/mm/ksm/merge_nodes
which control merging pages across different numa nodes.
When it is set to zero only pages from the same node are merged,
otherwise pages from all nodes can be merged together (default behavior).

Is it conceivable that admins may (in the future) want to merge only
across nodes that are below a given distance threshold?

I'm not asking to implement this, just whether the knob can be
introduced such that it's future-compatible.  Make it default to a
Very High Number and only allow setting it to 0 for now e.g.?  And
name it max_node_merge_distance (I'm bad at names)?

What do you think?

I started with exactly same idea as you described above in the first
RFC, link: https://lkml.org/lkml/2011/11/30/91
But this approach turned out to be more complicated than it looked
(see two last emails in thread) and complexity of solution would rise
a lot.

Regards,
Petr H

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