[PATCH v2 0/3] Updates to powerpc for robust CPU online/offline

[Peter Zijlstra]

On Sat, Aug 21, 2021 at 03:55:32PM +0530, Srikar Dronamraju wrote:
> Scheduler expects unique number of node distances to be available
> at boot. It uses node distance to calculate this unique node
> distances. On Power Servers, node distances for offline nodes is not
> available. However, Power Servers already knows unique possible node
> distances. Fake the offline node's distance_lookup_table entries so
> that all possible node distances are updated.
> 
> For example distance info from numactl from a fully populated 8 node
> system at boot may look like this.
> 
> node distances:
> node   0   1   2   3   4   5   6   7
>   0:  10  20  40  40  40  40  40  40
>   1:  20  10  40  40  40  40  40  40
>   2:  40  40  10  20  40  40  40  40
>   3:  40  40  20  10  40  40  40  40
>   4:  40  40  40  40  10  20  40  40
>   5:  40  40  40  40  20  10  40  40
>   6:  40  40  40  40  40  40  10  20
>   7:  40  40  40  40  40  40  20  10
> 
> However the same system when only two nodes are online at boot, then
> distance info from numactl will look like
> node distances:
> node   0   1
>   0:  10  20
>   1:  20  10
> 
> With the faked numa distance at boot, the node distance table will look
> like
> node   0   1   2
>   0:  10  20  40
>   1:  20  10  40
>   2:  40  40  10
> 
> The actual distance will be populated once the nodes are onlined.

How did you want all this merged? I picked up Valentin's patch, do you
want me to pick up these PowerPC patches in the same tree, or do you
want to route them seperately?