On Thu, 25 May 2017 12:37:40 -0500 Michael Bringmann <m...@linux.vnet.ibm.com> wrote:
> Removing or adding memory via the PowerPC hotplug interface shows > anomalies in the association between memory and nodes. The code > was updated to ensure that all nodes found at boot are still available > to subsequent DLPAR hotplug-memory operations, even if they are not > needed at boot time. > > Signed-off-by: Michael Bringmann <m...@linux.vnet.ibm.com> > --- > Changes in V2: > -- Simplify patches to ensure more nodes in possible map, removing > code from PowerPC numa.c that constrained possible map to size > of online map. > --- > arch/powerpc/mm/numa.c | 7 ------- > 1 file changed, 7 deletions(-) > > diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c > index 15c2dd5..18f3038 100644 > --- a/arch/powerpc/mm/numa.c > +++ b/arch/powerpc/mm/numa.c > @@ -907,13 +907,6 @@ void __init initmem_init(void) > > memblock_dump_all(); > > - /* > - * Reduce the possible NUMA nodes to the online NUMA nodes, > - * since we do not support node hotplug. This ensures that we > - * lower the maximum NUMA node ID to what is actually present. > - */ > - nodes_and(node_possible_map, node_possible_map, node_online_map); > - There is an overhead with turning this off if you have too many cgroups with the memory controller. I think this fix was added for a pathological test case. On my system I see 84 cgroups with 1 node, so the probable overhead is 84*255*sizeof(struct mem_cgroup_tree_per_node). I tried some patches to reduce the overhead, but those need more overhauling and rework. Balbir Singh.
