Re: [PATCH 2/2 v4] sched: Rewrite per entity runnable load average tracking

From: Yuyang Du
Date: Tue Jul 29 2014 - 05:56:06 EST

On Tue, Jul 29, 2014 at 11:39:11AM +0200, Peter Zijlstra wrote:
> > > For task, assuming its load.weight does not change much, yes, we can. But in theory, task's
> >
> > I would even say that the load_avg of a task should not be impacted by
> > an old priority value. Once, the priority of a task is changed, we
> > should only take into account this new priority to weight the load_avg
> > of the task
> So for tasks I would immediately agree, and I think for groups too,
> seeing how the group weight is based off of this avg, if you then
> include the old weight we'll get a feedback loop. This might not be
> desired as it would counteract the SMP movement of tasks.

Including the old weight can we get the *right* feedback. Because say until
weight is changed, we are balanced, changed weight leads to imbalance. Without
old weight, the imbalance is multiplied by the history, like we have never been
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