On 11/10/2009 04:36 PM, Anthony Liguori wrote:
A stats vq might solve this more cleanly?
actual and target are both really just stats. Had we implemented
those with a vq, I'd be inclined to agree with you but since they're
implemented in the config space, it seems natural to extend the
config space with other stats.
There is in fact a difference; actual and target are very rarely
updated, while the stats are updated very often. Using a vq means a
constant number of exits per batch instead of one exit per statistic.
If the vq is host-driven, it also allows the host to control the
update frequency dynamically (i.e. stop polling when there is no
memory pressure).