Re: question on NUMA page migration

From: Rik van Riel
Date: Fri Oct 19 2012 - 14:33:23 EST

On 10/19/2012 01:53 PM, Peter Zijlstra wrote:
On Fri, 2012-10-19 at 13:13 -0400, Rik van Riel wrote:

Another alternative might be to do the put_page inside
do_prot_none_numa(). That would be analogous to do_wp_page
disposing of the old page for the caller.

It'd have to be inside migrate_misplaced_page(), can't do before
isolate_lru_page() or the page might disappear. Doing it after is
(obviously) too late.

Keeping an extra refcount on the page might _still_
result in it disappearing from the process by some
other means, in-between you grabbing the refcount
and invoking migration of the page.

I am not real happy about NUMA migration introducing its own
migration mode...

You didn't seem to mind too much earlier, but I can remove it if you

Could have been reviewing fatigue :)

And yes, it would have been nice to not have a special
migration mode for sched/numa.

Speaking of, when do you guys plan to submit a (cleaned up)
version of the sched/numa patch series for review on lkml?

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