Aneesh Kumar K V <aneesh.kumar@xxxxxxxxxxxxx> writes: > On 8/9/22 8:34 AM, Huang, Ying wrote: >> "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxx> writes: >> >>> By default, all nodes are assigned to the default memory tier which >>> is the memory tier designated for nodes with DRAM >>> >>> Set dax kmem device node's tier to slower memory tier by assigning >>> abstract distance to MEMTIER_DEFAULT_DAX_ADISTANCE. Low-level drivers >>> like papr_scm or ACPI NFIT can initialize memory device type to a >>> more accurate value based on device tree details or HMAT. >> >> I don't know how ACPI NFIT can help here. Can you teach me? >> >> Per my understanding, we may use the information provided by ACPI SLIT >> or HMAT (or device tree via papr_scm) to create memory types. Before >> that is implemented, we just create a memory type with default abstract >> distance. >> > > My idea is to use ACPI NFIT driver that creates a persistent memory region > (nvdimm_region_create) to also create memory type and assign that to the > NUMA node mapping that region. For now NFIT driver manages all the persistent > memory region/DIMM creation (drivers/acpi/nfit/core.c). It can also do the > memory type creation using other ACPI information like SLIT/HMAT etc. Similarly > CXL driver can do the same using CDAT. I still think that it's better to create memory types in dax/kmem.c and CXL driver. But we can discuss further on that later. Best Regards, Huang, Ying
