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

From: Yang Shi
Date: Mon Nov 12 2018 - 13:44:32 EST


On Fri, Nov 9, 2018 at 3:24 PM Dan Williams <dan.j.williams@xxxxxxxxx> wrote:
>
> 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://lkml.org/lkml/2018/10/23/9
>
> Reported-by: Fan Du <fan.du@xxxxxxxxx>

Thanks for coming up with the patch quickly. We reported the problem
to Fan Du, and did a very similar, but preliminary, in-house
implementation.

This implementation looks good to me. Reviewed-by: Yang Shi
<yang.shi@xxxxxxxxxxxxxxxxx>

> Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
> Cc: "Oliver O'Halloran" <oohall@xxxxxxxxx>
> Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
> Cc: JÃrÃme Glisse <jglisse@xxxxxxxxxx>
> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
> ---
> arch/powerpc/platforms/pseries/papr_scm.c | 1 +
> drivers/acpi/nfit/core.c | 8 ++++++--
> drivers/acpi/numa.c | 1 +
> drivers/dax/bus.c | 4 +++-
> drivers/dax/bus.h | 3 ++-
> drivers/dax/dax-private.h | 4 ++++
> drivers/dax/pmem/core.c | 4 +++-
> drivers/nvdimm/e820.c | 1 +
> drivers/nvdimm/nd.h | 2 +-
> drivers/nvdimm/of_pmem.c | 1 +
> drivers/nvdimm/region_devs.c | 1 +
> include/linux/libnvdimm.h | 1 +
> 12 files changed, 25 insertions(+), 6 deletions(-)
>
> diff --git a/arch/powerpc/platforms/pseries/papr_scm.c b/arch/powerpc/platforms/pseries/papr_scm.c
> index ee9372b65ca5..6a0a35b872d1 100644
> --- a/arch/powerpc/platforms/pseries/papr_scm.c
> +++ b/arch/powerpc/platforms/pseries/papr_scm.c
> @@ -233,6 +233,7 @@ static int papr_scm_nvdimm_init(struct papr_scm_priv *p)
> memset(&ndr_desc, 0, sizeof(ndr_desc));
> ndr_desc.attr_groups = region_attr_groups;
> ndr_desc.numa_node = dev_to_node(&p->pdev->dev);
> + ndr_desc.target_node = ndr_desc.numa_node;
> ndr_desc.res = &p->res;
> ndr_desc.of_node = p->dn;
> ndr_desc.provider_data = p;
> diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
> index f8c638f3c946..2225e3de33ac 100644
> --- a/drivers/acpi/nfit/core.c
> +++ b/drivers/acpi/nfit/core.c
> @@ -2825,11 +2825,15 @@ static int acpi_nfit_register_region(struct acpi_nfit_desc *acpi_desc,
> ndr_desc->res = &res;
> ndr_desc->provider_data = nfit_spa;
> ndr_desc->attr_groups = acpi_nfit_region_attribute_groups;
> - if (spa->flags & ACPI_NFIT_PROXIMITY_VALID)
> + if (spa->flags & ACPI_NFIT_PROXIMITY_VALID) {
> ndr_desc->numa_node = acpi_map_pxm_to_online_node(
> spa->proximity_domain);
> - else
> + ndr_desc->target_node = acpi_map_pxm_to_node(
> + spa->proximity_domain);
> + } else {
> ndr_desc->numa_node = NUMA_NO_NODE;
> + ndr_desc->target_node = NUMA_NO_NODE;
> + }
>
> /*
> * Persistence domain bits are hierarchical, if
> diff --git a/drivers/acpi/numa.c b/drivers/acpi/numa.c
> index 274699463b4f..b9d86babb13a 100644
> --- a/drivers/acpi/numa.c
> +++ b/drivers/acpi/numa.c
> @@ -84,6 +84,7 @@ int acpi_map_pxm_to_node(int pxm)
>
> return node;
> }
> +EXPORT_SYMBOL(acpi_map_pxm_to_node);
>
> /**
> * acpi_map_pxm_to_online_node - Map proximity ID to online node
> diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
> index 568168500217..c620ad52d7e5 100644
> --- a/drivers/dax/bus.c
> +++ b/drivers/dax/bus.c
> @@ -214,7 +214,7 @@ static void dax_region_unregister(void *region)
> }
>
> struct dax_region *alloc_dax_region(struct device *parent, int region_id,
> - struct resource *res, unsigned int align,
> + struct resource *res, int target_node, unsigned int align,
> unsigned long pfn_flags)
> {
> struct dax_region *dax_region;
> @@ -244,6 +244,7 @@ struct dax_region *alloc_dax_region(struct device *parent, int region_id,
> dax_region->id = region_id;
> dax_region->align = align;
> dax_region->dev = parent;
> + dax_region->target_node = target_node;
> if (sysfs_create_groups(&parent->kobj, dax_region_attribute_groups)) {
> kfree(dax_region);
> return NULL;
> @@ -348,6 +349,7 @@ struct dev_dax *__devm_create_dev_dax(struct dax_region *dax_region, int id,
>
> dev_dax->dax_dev = dax_dev;
> dev_dax->region = dax_region;
> + dev_dax->target_node = dax_region->target_node;
> kref_get(&dax_region->kref);
>
> inode = dax_inode(dax_dev);
> diff --git a/drivers/dax/bus.h b/drivers/dax/bus.h
> index ce977552ffb5..8619e3299943 100644
> --- a/drivers/dax/bus.h
> +++ b/drivers/dax/bus.h
> @@ -10,7 +10,8 @@ struct dax_device;
> struct dax_region;
> void dax_region_put(struct dax_region *dax_region);
> struct dax_region *alloc_dax_region(struct device *parent, int region_id,
> - struct resource *res, unsigned int align, unsigned long flags);
> + struct resource *res, int target_node, unsigned int align,
> + unsigned long flags);
>
> enum dev_dax_subsys {
> DEV_DAX_BUS,
> diff --git a/drivers/dax/dax-private.h b/drivers/dax/dax-private.h
> index a82ce48f5884..a45612148ca0 100644
> --- a/drivers/dax/dax-private.h
> +++ b/drivers/dax/dax-private.h
> @@ -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;
> diff --git a/drivers/dax/pmem/core.c b/drivers/dax/pmem/core.c
> index bdcff1b14e95..f71019ce0647 100644
> --- a/drivers/dax/pmem/core.c
> +++ b/drivers/dax/pmem/core.c
> @@ -20,6 +20,7 @@ struct dev_dax *__dax_pmem_probe(struct device *dev, enum dev_dax_subsys subsys)
> struct nd_namespace_common *ndns;
> struct nd_dax *nd_dax = to_nd_dax(dev);
> struct nd_pfn *nd_pfn = &nd_dax->nd_pfn;
> + struct nd_region *nd_region = to_nd_region(dev->parent);
>
> ndns = nvdimm_namespace_common_probe(dev);
> if (IS_ERR(ndns))
> @@ -52,7 +53,8 @@ struct dev_dax *__dax_pmem_probe(struct device *dev, enum dev_dax_subsys subsys)
> memcpy(&res, &pgmap.res, sizeof(res));
> res.start += offset;
> dax_region = alloc_dax_region(dev, region_id, &res,
> - le32_to_cpu(pfn_sb->align), PFN_DEV|PFN_MAP);
> + nd_region->target_node, le32_to_cpu(pfn_sb->align),
> + PFN_DEV|PFN_MAP);
> if (!dax_region)
> return ERR_PTR(-ENOMEM);
>
> diff --git a/drivers/nvdimm/e820.c b/drivers/nvdimm/e820.c
> index 521eaf53a52a..36be9b619187 100644
> --- a/drivers/nvdimm/e820.c
> +++ b/drivers/nvdimm/e820.c
> @@ -47,6 +47,7 @@ static int e820_register_one(struct resource *res, void *data)
> ndr_desc.res = res;
> ndr_desc.attr_groups = e820_pmem_region_attribute_groups;
> ndr_desc.numa_node = e820_range_to_nid(res->start);
> + ndr_desc.target_node = ndr_desc.numa_node;
> set_bit(ND_REGION_PAGEMAP, &ndr_desc.flags);
> if (!nvdimm_pmem_region_create(nvdimm_bus, &ndr_desc))
> return -ENXIO;
> diff --git a/drivers/nvdimm/nd.h b/drivers/nvdimm/nd.h
> index e79cc8e5c114..623216545cc8 100644
> --- a/drivers/nvdimm/nd.h
> +++ b/drivers/nvdimm/nd.h
> @@ -153,7 +153,7 @@ struct nd_region {
> u16 ndr_mappings;
> u64 ndr_size;
> u64 ndr_start;
> - int id, num_lanes, ro, numa_node;
> + int id, num_lanes, ro, numa_node, target_node;
> void *provider_data;
> struct kernfs_node *bb_state;
> struct badblocks bb;
> diff --git a/drivers/nvdimm/of_pmem.c b/drivers/nvdimm/of_pmem.c
> index 0a701837dfc0..ecaaa27438e2 100644
> --- a/drivers/nvdimm/of_pmem.c
> +++ b/drivers/nvdimm/of_pmem.c
> @@ -68,6 +68,7 @@ static int of_pmem_region_probe(struct platform_device *pdev)
> memset(&ndr_desc, 0, sizeof(ndr_desc));
> ndr_desc.attr_groups = region_attr_groups;
> ndr_desc.numa_node = dev_to_node(&pdev->dev);
> + ndr_desc.target_node = ndr_desc.numa_node;
> ndr_desc.res = &pdev->resource[i];
> ndr_desc.of_node = np;
> set_bit(ND_REGION_PAGEMAP, &ndr_desc.flags);
> diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c
> index 174a418cb171..86cd425b786d 100644
> --- a/drivers/nvdimm/region_devs.c
> +++ b/drivers/nvdimm/region_devs.c
> @@ -1060,6 +1060,7 @@ static struct nd_region *nd_region_create(struct nvdimm_bus *nvdimm_bus,
> nd_region->flags = ndr_desc->flags;
> nd_region->ro = ro;
> nd_region->numa_node = ndr_desc->numa_node;
> + nd_region->target_node = ndr_desc->target_node;
> ida_init(&nd_region->ns_ida);
> ida_init(&nd_region->btt_ida);
> ida_init(&nd_region->pfn_ida);
> diff --git a/include/linux/libnvdimm.h b/include/linux/libnvdimm.h
> index 097072c5a852..941102c0c81f 100644
> --- a/include/linux/libnvdimm.h
> +++ b/include/linux/libnvdimm.h
> @@ -124,6 +124,7 @@ struct nd_region_desc {
> void *provider_data;
> int num_lanes;
> int numa_node;
> + int target_node;
> unsigned long flags;
> struct device_node *of_node;
> };
>