Re: [PATCH 2.5.58] new NUMA scheduler: fix

Ingo Molnar
2003-01-17T07:10:38Z

On Thu, 16 Jan 2003, Martin J. Bligh wrote:

> If I understand that correctly (and I'm not sure I do), you're saying
> you don't think the exec time balance should go global? That would break
> most of the concept ... *something* has to distribute stuff around
> nodes, and the exec point is the cheapest time to do that (least
> "weight" to move. [...]

the exec()-time balancing is special, since it only moves the task in
question - so the 'push' should indeed be a global decision. _But_, exec()
is also a natural balancing point for the local node (we potentially just
got rid of a task, which might create imbalance within the node), so it
might make sense to do a 'local' balancing run as well, if the exec()-ing
task was indeed pushed to another node.

> At the moment, the high-freq balancer is only inside a node. Exec
> balancing is global, and the "low-frequency" balancer is global. WRT the
> idle-time balancing, I agree with what I *think* you're saying ... this
> shouldn't clock up the rq->nr_balanced counter ... this encourages too
> much cross-node stealing. I'll hack that change out and see what it does
> to the numbers.

yes, this should also further unify the SMP and NUMA balancing code.

Ingo