On Tue, 2017-11-28 at 22:58:36 UTC, Michael Bringmann wrote: > On powerpc systems which allow 'hot-add' of CPU or memory resources, > it may occur that the new resources are to be inserted into nodes > that were not used for these resources at bootup. In the kernel, > any node that is used must be defined and initialized. These empty > nodes may occur when, > > * Dedicated vs. shared resources. Shared resources require > information such as the VPHN hcall for CPU assignment to nodes. > Associativity decisions made based on dedicated resource rules, > such as associativity properties in the device tree, may vary > from decisions made using the values returned by the VPHN hcall. > * memoryless nodes at boot. Nodes need to be defined as 'possible' > at boot for operation with other code modules. Previously, the > powerpc code would limit the set of possible nodes to those which > have memory assigned at boot, and were thus online. Subsequent > add/remove of CPUs or memory would only work with this subset of > possible nodes. > * memoryless nodes with CPUs at boot. Due to the previous restriction > on nodes, nodes that had CPUs but no memory were being collapsed > into other nodes that did have memory at boot. In practice this > meant that the node assignment presented by the runtime kernel > differed from the affinity and associativity attributes presented > by the device tree or VPHN hcalls. Nodes that might be known to > the pHyp were not 'possible' in the runtime kernel because they did > not have memory at boot. > > This patch ensures that sufficient nodes are defined to support > configuration requirements after boot, as well as at boot. This > patch set fixes a couple of problems. > > * Nodes known to powerpc to be memoryless at boot, but to have > CPUs in them are allowed to be 'possible' and 'online'. Memory > allocations for those nodes are taken from another node that does > have memory until and if memory is hot-added to the node. > * Nodes which have no resources assigned at boot, but which may still > be referenced subsequently by affinity or associativity attributes, > are kept in the list of 'possible' nodes for powerpc. Hot-add of > memory or CPUs to the system can reference these nodes and bring > them online instead of redirecting to one of the set of nodes that > were known to have memory at boot. > > This patch extracts the value of the lowest domain level (number of > allocable resources) from the device tree property > "ibm,max-associativity-domains" to use as the maximum number of nodes > to setup as possibly available in the system. This new setting will > override the instruction, > > nodes_and(node_possible_map, node_possible_map, node_online_map); > > presently seen in the function arch/powerpc/mm/numa.c:initmem_init(). > > If the "ibm,max-associativity-domains" property is not present at boot, > no operation will be performed to define or enable additional nodes, or > enable the above 'nodes_and()'. > > Signed-off-by: Michael Bringmann <m...@linux.vnet.ibm.com> > Reviewed-by: Nathan Fontenot <nf...@linux.vnet.ibm.com>
Series applied to powerpc next, thanks. https://git.kernel.org/powerpc/c/a346137e9142b039fd13af2e59696e cheers
