Re: RFC vmstat: On demand vmstat threads

[Christoph Lameter]

On Fri, 20 Sep 2013, Thomas Gleixner wrote:

> Now when a cpu becomes isolated we stop the callback scheduling on
> that cpu and assign it to the cpu with the smallest NUMA
> distance. So that cpu will process the data for itself and for the
> newly isolated cpu.

That is not possible for many percpu threads since they rely on running on
a specific cpu for optimization purposes. Running on a different processor
makes these threads racy.

What is needed is to be able to switch these things off and on. Something
on a different cpu may monitor if processing on that specific cpu is
needed or not but it cannot perform the vmstat updates.

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