[patch 0/2] per-CPU vmstat thresholds and vmstat worker disablement

[Marcelo Tosatti]

The per-CPU vmstat worker is a problem on -RT workloads (because
ideally the CPU is entirely reserved for the -RT app, without
interference). The worker transfers accumulated per-CPU 
vmstat counters to global counters.

To resolve the problem, create two tunables:

* Userspace configurable per-CPU vmstat threshold: by default the 
VM code calculates the size of the per-CPU vmstat arrays. This 
tunable allows userspace to configure the values.

* Userspace configurable per-CPU vmstat worker: allow disabling
the per-CPU vmstat worker.