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acpi/nfit, device-dax: Identify differentiated memory with a unique numa-node

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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 <fan.du@intel.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Oliver O'Halloran" <oohall@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Reviewed-by: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This commit is contained in:
Dan Williams
2018-11-09 12:43:07 -08:00
parent 730926c3b0
commit 8fc5c73554
13 changed files with 30 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
drivers/dax/dax-private.h
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@@ -26,6 +26,7 @@ void dax_bus_exit(void);
/**
* struct dax_region - mapping infrastructure for dax devices
* @id: kernel-wide unique region for a memory range
* @target_node: effective numa node if this memory range is onlined
* @kref: to pin while other agents have a need to do lookups
* @dev: parent device backing this region
* @align: allocation and mapping alignment for child dax devices
@@ -34,6 +35,7 @@ void dax_bus_exit(void);
*/
struct dax_region {
int id;
int target_node;
struct kref kref;
struct device *dev;
unsigned int align;
@@ -46,6 +48,7 @@ struct dax_region {
* data while the device is activated in the driver.
* @region - parent region
* @dax_dev - core dax functionality
* @target_node: effective numa node if dev_dax memory range is onlined
* @dev - device core
* @pgmap - pgmap for memmap setup / lifetime (driver owned)
* @ref: pgmap reference count (driver owned)
@@ -54,6 +57,7 @@ struct dax_region {
struct dev_dax {
struct dax_region *region;
struct dax_device *dax_dev;
int target_node;
struct device dev;
struct dev_pagemap pgmap;
struct percpu_ref ref;