From 8fc5c73554db0ac18c0c6ac5b2099ab917f83bdf Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Fri, 9 Nov 2018 12:43:07 -0800 Subject: acpi/nfit, device-dax: Identify differentiated memory with a unique numa-node MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Persistent memory, as described by the ACPI NFIT (NVDIMM Firmware Interface Table), is the first known instance of a memory range described by a unique "target" proximity domain. Where "initiator" and "target" proximity domains is an approach that the ACPI HMAT (Heterogeneous Memory Attributes Table) uses to described the unique performance properties of a memory range relative to a given initiator (e.g. CPU or DMA device). Currently the numa-node for a /dev/pmemX block-device or /dev/daxX.Y char-device follows the traditional notion of 'numa-node' where the attribute conveys the closest online numa-node. That numa-node attribute is useful for cpu-binding and memory-binding processes *near* the device. However, when the memory range backing a 'pmem', or 'dax' device is onlined (memory hot-add) the memory-only-numa-node representing that address needs to be differentiated from the set of online nodes. In other words, the numa-node association of the device depends on whether you can bind processes *near* the cpu-numa-node in the offline device-case, or bind process *on* the memory-range directly after the backing address range is onlined. Allow for the case that platform firmware describes persistent memory with a unique proximity domain, i.e. when it is distinct from the proximity of DRAM and CPUs that are on the same socket. Plumb the Linux numa-node translation of that proximity through the libnvdimm region device to namespaces that are in device-dax mode. With this in place the proposed kmem driver [1] can optionally discover a unique numa-node number for the address range as it transitions the memory from an offline state managed by a device-driver to an online memory range managed by the core-mm. [1]: https://lore.kernel.org/lkml/20181022201317.8558C1D8@viggo.jf.intel.com Reported-by: Fan Du Cc: Michael Ellerman Cc: "Oliver O'Halloran" Cc: Dave Hansen Cc: Jérôme Glisse Reviewed-by: Yang Shi Signed-off-by: Dan Williams --- include/linux/acpi.h | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'include/linux/acpi.h') diff --git a/include/linux/acpi.h b/include/linux/acpi.h index 87715f20b69a..eddf2736e5a6 100644 --- a/include/linux/acpi.h +++ b/include/linux/acpi.h @@ -400,12 +400,17 @@ extern bool acpi_osi_is_win8(void); #ifdef CONFIG_ACPI_NUMA int acpi_map_pxm_to_online_node(int pxm); +int acpi_map_pxm_to_node(int pxm); int acpi_get_node(acpi_handle handle); #else static inline int acpi_map_pxm_to_online_node(int pxm) { return 0; } +static inline int acpi_map_pxm_to_node(int pxm) +{ + return 0; +} static inline int acpi_get_node(acpi_handle handle) { return 0; -- cgit v1.2.3