Re: Off topic: Numactl "distance" wrong

[Brice Goglin <Brice.Goglin@inria.fr>]

KOSAKI Motohiro wrote:
>> That's not enough. You would need to redo all the zone fallback tables
>> in the VM that are initialized based on topology, do new scheduler
>> topologies and all kind of other stuff.
> 
> I think this is very good viewpoint.
> 
> The rebuilding zone fallback table and scheduler topologies need to add
> new lock.

Could you clarify how changing numa distances could break
zone fallback tables and scheduler topologies?

> Oh well, who need memory and scheduler performance regression?
> Then, its /sys interface isn't so useful.

If changing the slit table at runtime is too hard, what about
changing it at boot through a new kernel command-line parameter?

> I don't think the manual setting of node distance improve
> opteron's (or another small machine) performance.

Well, some user-space application may use these distances
to improve their binding. Maybe nobody does yet because
numa distances have never been available on x86_64 boxes...

Brice