Re: [PATCH 18/19] sched, numa: Per task memory placement for bigprocesses

From: Rik van Riel
Date: Tue Jul 31 2012 - 17:56:19 EST


On 07/31/2012 03:12 PM, Peter Zijlstra wrote:
Probability says that the task faulting on a page after we protect it,
is most likely to be the task that uses that page most.

To decrease the likelyhood of acting on a false relation, we only
migrate a page when two consecutive samples are from the same task.

I'm still not entirely convinced this scheme is sound, esp. for things
like virtualization and n:m threading solutions in general the
compute<->task relation is fundamentally untrue.

Again, we may need some additional code on top in the future,
eg. something like Andrea's policy that tries grouping related
tasks/threads together, but this looks like a very good way
to start.

We can introduce complexity if it is needed. Simplicity is good.

Acked-by: Rik van Riel

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