On Thu, Oct 25, 2012 at 02:16:47PM +0200, Peter Zijlstra wrote:

Add a 1 second delay before starting to scan the working set of
a task and starting to balance it amongst nodes.

[ note that before the constant per task WSS sampling rate patch
  the initial scan would happen much later still, in effect that
  patch caused this regression. ]

The theory is that short-run tasks benefit very little from NUMA
placement: they come and go, and they better stick to the node
they were started on. As tasks mature and rebalance to other CPUs
and nodes, so does their NUMA placement have to change and so
does it start to matter more and more.

Yeah, ok. It's done by wall time, right? Should it be CPU time in case
it spent the first second asleep?

-- 
Mel Gorman
SUSE Labs

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