[RFC PATCH 7/8] powerpc/pseries: Add support for FORM2 associativity
David Gibson
david at gibson.dropbear.id.au
Tue Jun 15 13:53:22 AEST 2021
On Mon, Jun 14, 2021 at 10:10:02PM +0530, Aneesh Kumar K.V wrote:
> Signed-off-by: Daniel Henrique Barboza <danielhb413 at gmail.com>
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar at linux.ibm.com>
> ---
> Documentation/powerpc/associativity.rst | 139 ++++++++++++++++++++
> arch/powerpc/include/asm/firmware.h | 3 +-
> arch/powerpc/include/asm/prom.h | 1 +
> arch/powerpc/kernel/prom_init.c | 3 +-
> arch/powerpc/mm/numa.c | 149 +++++++++++++++++++++-
> arch/powerpc/platforms/pseries/firmware.c | 1 +
> 6 files changed, 290 insertions(+), 6 deletions(-)
> create mode 100644 Documentation/powerpc/associativity.rst
>
> diff --git a/Documentation/powerpc/associativity.rst b/Documentation/powerpc/associativity.rst
> new file mode 100644
> index 000000000000..58abedea81d7
> --- /dev/null
> +++ b/Documentation/powerpc/associativity.rst
> @@ -0,0 +1,139 @@
> +============================
> +NUMA resource associativity
> +=============================
> +
> +Associativity represents the groupings of the various platform resources into
> +domains of substantially similar mean performance relative to resources outside
> +of that domain. Resources subsets of a given domain that exhibit better
> +performance relative to each other than relative to other resources subsets
> +are represented as being members of a sub-grouping domain. This performance
> +characteristic is presented in terms of NUMA node distance within the Linux kernel.
> +From the platform view, these groups are also referred to as domains.
> +
> +PAPR interface currently supports two different ways of communicating these resource
You describe form 2 below as well, which contradicts this.
> +grouping details to the OS. These are referred to as Form 0 and Form 1 associativity grouping.
> +Form 0 is the older format and is now considered deprecated.
> +
> +Hypervisor indicates the type/form of associativity used via "ibm,arcitecture-vec-5 property".
> +Bit 0 of byte 5 in the "ibm,architecture-vec-5" property indicates usage of Form 0 or Form 1.
> +A value of 1 indicates the usage of Form 1 associativity.
> +
> +Form 0
> +-----
> +Form 0 associativity supports only two NUMA distance (LOCAL and REMOTE).
> +
> +Form 1
> +-----
> +With Form 1 a combination of ibm,associativity-reference-points and ibm,associativity
> +device tree properties are used to determine the NUMA distance between resource groups/domains.
> +
> +The “ibm,associativity” property contains one or more lists of numbers (domainID)
> +representing the resource’s platform grouping domains.
> +
> +The “ibm,associativity-reference-points” property contains one or more list of numbers
> +(domain index) that represents the 1 based ordinal in the associativity lists of the most
> +significant boundary, with subsequent entries indicating progressively less significant boundaries.
> +
> +Linux kernel uses the domain id of the most significant boundary (aka primary domain)
I thought we used the *least* significant boundary (the smallest
grouping, not the largest). That is, the last index, not the first.
Actually... come to think of it, I'm not even sure how to interpret
"most significant". Does that mean a change in grouping at that "most
significant" level results in the largest perfomance difference?
> +as the NUMA node id. Linux kernel computes NUMA distance between two domains by
> +recursively comparing if they belong to the same higher-level domains. For mismatch
> +at every higher level of the resource group, the kernel doubles the NUMA distance between
> +the comparing domains.
> +
> +Form 2
> +-------
> +Form 2 associativity format adds separate device tree properties representing NUMA node distance
> +thereby making the node distance computation flexible. Form 2 also allows flexible primary
> +domain numbering. With numa distance computation now detached from the index value of
> +"ibm,associativity" property, Form 2 allows a large number of primary domain ids at the
> +same domain index representing resource groups of different
> performance/latency characteristics.
The meaning of "domain index" is not clear to me here.
> +
> +Hypervisor indicates the usage of FORM2 associativity using bit 2 of byte 5 in the
> +"ibm,architecture-vec-5" property.
> +
> +"ibm,numa-lookup-index-table" property contains one or more list numbers representing
> +the domainIDs present in the system. The offset of the domainID in this property is considered
> +the domainID index.
You haven't really introduced the term "domainID". Is "domainID
index" the same as "domain index" above? It's not clear to me.
The distinction between "domain index" and "primary domain id" is also
not clear to me.
> +prop-encoded-array: The number N of the domainIDs encoded as with encode-int, followed by
> +N domainID encoded as with encode-int
> +
> +For ex:
> +ibm,numa-lookup-index-table = {4, 0, 8, 250, 252}, domainID index for domainID 8 is 1.
Above you say "Form 2 allows a large number of primary domain ids at
the same domain index", but this encoding doesn't appear to permit
that.
> +"ibm,numa-distance-table" property contains one or more list of numbers representing the NUMA
> +distance between resource groups/domains present in the system.
> +
> +prop-encoded-array: The number N of the distance values encoded as with encode-int, followed by
> +N distance values encoded as with encode-bytes. The max distance value we could encode is 255.
> +
> +For ex:
> +ibm,numa-lookup-index-table = {3, 0, 8, 40}
> +ibm,numa-distance-table = {9, 1, 2, 8, 2, 1, 16, 8, 16, 1}
> +
> + | 0 8 40
> +--|------------
> + |
> +0 | 10 20 80
> + |
> +8 | 20 10 160
> + |
> +40| 80 160 10
What's the reason for multiplying the values by 10 in the expanded
table version?
> +
> +With Form2 "ibm,associativity" for resources is listed as below:
> +
> +"ibm,associativity" property for resources in node 0, 8 and 40
> +{ 4, 6, 7, 0, 0}
> +{ 4, 6, 9, 8, 8}
> +{ 4, 6, 7, 0, 40}
> +
> +With "ibm,associativity-reference-points" { 0x4, 0x3, 0x2 }
> +
> +With Form2 the primary domainID and secondary domainID are used to identify the NUMA nodes
What the heck is the secondary domainID?
> +the kernel should use when using persistent memory devices. Persistent memory devices
> +can also be used as regular memory using DAX KMEM driver and primary domainID indicates
> +the numa node number OS should use when using these devices as regular memory. Secondary
> +domainID is the numa node number that should be used when using this device as
> +persistent memory. In the later case, we are interested in the locality of the
> +device to an established numa node. In the above example, if the last row represents a
> +persistent memory device/resource, NUMA node number 40 will be used when using the device
> +as regular memory and NUMA node number 0 will be the device numa node when using it as
> +a persistent memory device.
> +
> +Each resource (drcIndex) now also supports additional optional device tree properties.
> +These properties are marked optional because the platform can choose not to export
> +them and provide the system topology details using the earlier defined device tree
> +properties alone. The optional device tree properties are used when adding new resources
> +(DLPAR) and when the platform didn't provide the topology details of the domain which
> +contains the newly added resource during boot.
> +
> +"ibm,numa-lookup-index" property contains a number representing the domainID index to be used
> +when building the NUMA distance of the numa node to which this resource belongs. The domain id
> +of the new resource can be obtained from the existing "ibm,associativity" property. This
> +can be used to build distance information of a newly onlined NUMA node via DLPAR operation.
> +The value is 1 based array index value.
Am I correct in thinking that if we have an entirely form2 world, we'd
only need this and the ibm,associativity properties could be dropped?
> +
> +prop-encoded-array: An integer encoded as with encode-int specifying the domainID index
> +
> +"ibm,numa-distance" property contains one or more list of numbers presenting the NUMA distance
> +from this resource domain to other resources.
IIUC this is about extending the global distance table with
information for a new node. Is that correct?
The global distance table allows for the possibility of asymmetric
distances between nodes, but this does not. Is that intentional?
> +prop-encoded-array: The number N of the distance values encoded as with encode-int, followed by
> +N distance values encoded as with encode-bytes. The max distance value we could encode is 255.
> +
> +For ex:
> +ibm,associativity = { 4, 5, 6, 7, 50}
> +ibm,numa-lookup-index = { 4 }
> +ibm,numa-distance = {8, 16, 32, 8, 1, 16, 32, 8, 1}
> +
> +resulting in a new toplogy as below.
> + | 0 8 40 50
> +--|------------------
> + |
> +0 | 10 20 80 160
> + |
> +8 | 20 10 160 320
> + |
> +40| 80 160 10 80
> + |
> +50| 160 320 80 10
> diff --git a/arch/powerpc/include/asm/firmware.h b/arch/powerpc/include/asm/firmware.h
> index 60b631161360..97a3bd9ffeb9 100644
> --- a/arch/powerpc/include/asm/firmware.h
> +++ b/arch/powerpc/include/asm/firmware.h
> @@ -53,6 +53,7 @@
> #define FW_FEATURE_ULTRAVISOR ASM_CONST(0x0000004000000000)
> #define FW_FEATURE_STUFF_TCE ASM_CONST(0x0000008000000000)
> #define FW_FEATURE_RPT_INVALIDATE ASM_CONST(0x0000010000000000)
> +#define FW_FEATURE_FORM2_AFFINITY ASM_CONST(0x0000020000000000)
>
> #ifndef __ASSEMBLY__
>
> @@ -73,7 +74,7 @@ enum {
> FW_FEATURE_HPT_RESIZE | FW_FEATURE_DRMEM_V2 |
> FW_FEATURE_DRC_INFO | FW_FEATURE_BLOCK_REMOVE |
> FW_FEATURE_PAPR_SCM | FW_FEATURE_ULTRAVISOR |
> - FW_FEATURE_RPT_INVALIDATE,
> + FW_FEATURE_RPT_INVALIDATE | FW_FEATURE_FORM2_AFFINITY,
> FW_FEATURE_PSERIES_ALWAYS = 0,
> FW_FEATURE_POWERNV_POSSIBLE = FW_FEATURE_OPAL | FW_FEATURE_ULTRAVISOR,
> FW_FEATURE_POWERNV_ALWAYS = 0,
> diff --git a/arch/powerpc/include/asm/prom.h b/arch/powerpc/include/asm/prom.h
> index df9fec9d232c..5c80152e8f18 100644
> --- a/arch/powerpc/include/asm/prom.h
> +++ b/arch/powerpc/include/asm/prom.h
> @@ -149,6 +149,7 @@ extern int of_read_drc_info_cell(struct property **prop,
> #define OV5_XCMO 0x0440 /* Page Coalescing */
> #define OV5_FORM1_AFFINITY 0x0580 /* FORM1 NUMA affinity */
> #define OV5_PRRN 0x0540 /* Platform Resource Reassignment */
> +#define OV5_FORM2_AFFINITY 0x0520 /* Form2 NUMA affinity */
> #define OV5_HP_EVT 0x0604 /* Hot Plug Event support */
> #define OV5_RESIZE_HPT 0x0601 /* Hash Page Table resizing */
> #define OV5_PFO_HW_RNG 0x1180 /* PFO Random Number Generator */
> diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c
> index 64b9593038a7..496fdac54c29 100644
> --- a/arch/powerpc/kernel/prom_init.c
> +++ b/arch/powerpc/kernel/prom_init.c
> @@ -1070,7 +1070,8 @@ static const struct ibm_arch_vec ibm_architecture_vec_template __initconst = {
> #else
> 0,
> #endif
> - .associativity = OV5_FEAT(OV5_FORM1_AFFINITY) | OV5_FEAT(OV5_PRRN),
> + .associativity = OV5_FEAT(OV5_FORM1_AFFINITY) | OV5_FEAT(OV5_PRRN) |
> + OV5_FEAT(OV5_FORM2_AFFINITY),
> .bin_opts = OV5_FEAT(OV5_RESIZE_HPT) | OV5_FEAT(OV5_HP_EVT),
> .micro_checkpoint = 0,
> .reserved0 = 0,
> diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
> index 696e5bfe1414..86cd2af014f7 100644
> --- a/arch/powerpc/mm/numa.c
> +++ b/arch/powerpc/mm/numa.c
> @@ -56,12 +56,17 @@ static int n_mem_addr_cells, n_mem_size_cells;
>
> #define FORM0_AFFINITY 0
> #define FORM1_AFFINITY 1
> +#define FORM2_AFFINITY 2
> static int affinity_form;
>
> #define MAX_DISTANCE_REF_POINTS 4
> static int max_domain_index;
> static const __be32 *distance_ref_points;
> static int distance_lookup_table[MAX_NUMNODES][MAX_DISTANCE_REF_POINTS];
> +static int numa_distance_table[MAX_NUMNODES][MAX_NUMNODES] = {
> + [0 ... MAX_NUMNODES - 1] = { [0 ... MAX_NUMNODES - 1] = -1 }
> +};
> +static int numa_id_index_table[MAX_NUMNODES];
>
> /*
> * Allocate node_to_cpumask_map based on number of available nodes
> @@ -166,6 +171,27 @@ static void unmap_cpu_from_node(unsigned long cpu)
> }
> #endif /* CONFIG_HOTPLUG_CPU || CONFIG_PPC_SPLPAR */
>
> +/*
> + * With FORM2 if we are not using logical domain ids, we will find
> + * both primary and seconday domains with same value. Hence always
> + * start comparison from secondary domains
> + */
> +static int __cpu_form2_distance(__be32 *cpu1_assoc, __be32 *cpu2_assoc)
> +{
> + int dist = 0;
> +
> + int i, index;
> +
> + for (i = 1; i < max_domain_index; i++) {
> + index = be32_to_cpu(distance_ref_points[i]);
> + if (cpu1_assoc[index] == cpu2_assoc[index])
> + break;
> + dist++;
> + }
> +
> + return dist;
> +}
> +
> static int __cpu_form1_distance(__be32 *cpu1_assoc, __be32 *cpu2_assoc)
> {
> int dist = 0;
> @@ -178,7 +204,6 @@ static int __cpu_form1_distance(__be32 *cpu1_assoc, __be32 *cpu2_assoc)
> break;
> dist++;
> }
> -
> return dist;
> }
>
> @@ -186,8 +211,9 @@ int cpu_distance(__be32 *cpu1_assoc, __be32 *cpu2_assoc)
> {
> /* We should not get called with FORM0 */
> VM_WARN_ON(affinity_form == FORM0_AFFINITY);
> -
> - return __cpu_form1_distance(cpu1_assoc, cpu2_assoc);
> + if (affinity_form == FORM1_AFFINITY)
> + return __cpu_form1_distance(cpu1_assoc, cpu2_assoc);
> + return __cpu_form2_distance(cpu1_assoc, cpu2_assoc);
> }
>
> /* must hold reference to node during call */
> @@ -201,7 +227,9 @@ int __node_distance(int a, int b)
> int i;
> int distance = LOCAL_DISTANCE;
>
> - if (affinity_form == FORM0_AFFINITY)
> + if (affinity_form == FORM2_AFFINITY)
> + return numa_distance_table[a][b];
> + else if (affinity_form == FORM0_AFFINITY)
> return ((a == b) ? LOCAL_DISTANCE : REMOTE_DISTANCE);
>
> for (i = 0; i < max_domain_index; i++) {
> @@ -303,15 +331,116 @@ static void initialize_form1_numa_distance(struct device_node *node)
>
> /*
> * Used to update distance information w.r.t newly added node.
> + * ibm,numa-lookup-index -> 4
> + * ibm,numa-distance -> {5, 20, 40, 60, 80, 10 }
> */
> void update_numa_distance(struct device_node *node)
> {
> + int i, nid, other_nid, other_nid_index = 0;
> + const __be32 *numa_indexp;
> + const __u8 *numa_distancep;
> + int numa_index, max_numa_index, numa_distance;
> +
> if (affinity_form == FORM0_AFFINITY)
> return;
> else if (affinity_form == FORM1_AFFINITY) {
> initialize_form1_numa_distance(node);
> return;
> }
> + /* FORM2 affinity */
> +
> + nid = of_node_to_nid_single(node);
> + if (nid == NUMA_NO_NODE)
> + return;
> +
> + /* Already initialized */
> + if (numa_distance_table[nid][nid] != -1)
> + return;
> + /*
> + * update node distance if not already populated.
> + */
> + numa_distancep = of_get_property(node, "ibm,numa-distance", NULL);
> + if (!numa_distancep)
> + return;
> +
> + numa_indexp = of_get_property(node, "ibm,numa-lookup-index", NULL);
> + if (!numa_indexp)
> + return;
> +
> + numa_index = of_read_number(numa_indexp, 1);
> + /*
> + * update the numa_id_index_table. Device tree look at index table as
> + * 1 based array indexing.
> + */
> + numa_id_index_table[numa_index - 1] = nid;
> +
> + max_numa_index = of_read_number((const __be32 *)numa_distancep, 1);
> + VM_WARN_ON(max_numa_index != 2 * numa_index);
> + /* Skip the size which is encoded int */
> + numa_distancep += sizeof(__be32);
> +
> + /*
> + * First fill the distance information from other node to this node.
> + */
> + other_nid_index = 0;
> + for (i = 0; i < numa_index; i++) {
> + numa_distance = numa_distancep[i];
> + other_nid = numa_id_index_table[other_nid_index++];
> + numa_distance_table[other_nid][nid] = numa_distance;
> + }
> +
> + other_nid_index = 0;
> + for (; i < max_numa_index; i++) {
> + numa_distance = numa_distancep[i];
> + other_nid = numa_id_index_table[other_nid_index++];
> + numa_distance_table[nid][other_nid] = numa_distance;
> + }
> +}
> +
> +/*
> + * ibm,numa-lookup-index-table= {N, domainid1, domainid2, ..... domainidN}
> + * ibm,numa-distance-table = { N, 1, 2, 4, 5, 1, 6, .... N elements}
> + */
> +static void initialize_form2_numa_distance_lookup_table(struct device_node *root)
> +{
> + const __u8 *numa_dist_table;
> + const __be32 *numa_lookup_index;
> + int numa_dist_table_length;
> + int max_numa_index, distance_index;
> + int i, curr_row = 0, curr_column = 0;
> +
> + numa_lookup_index = of_get_property(root, "ibm,numa-lookup-index-table", NULL);
> + max_numa_index = of_read_number(&numa_lookup_index[0], 1);
> +
> + /* first element of the array is the size and is encode-int */
> + numa_dist_table = of_get_property(root, "ibm,numa-distance-table", NULL);
> + numa_dist_table_length = of_read_number((const __be32 *)&numa_dist_table[0], 1);
> + /* Skip the size which is encoded int */
> + numa_dist_table += sizeof(__be32);
> +
> + pr_debug(" numa_dist_table_len = %d, numa_dist_indexes_len = %d \n",
> + numa_dist_table_length, max_numa_index);
> +
> + for (i = 0; i < max_numa_index; i++)
> + /* +1 skip the max_numa_index in the property */
> + numa_id_index_table[i] = of_read_number(&numa_lookup_index[i + 1], 1);
> +
> +
> + VM_WARN_ON(numa_dist_table_length != max_numa_index * max_numa_index);
> +
> + for (distance_index = 0; distance_index < numa_dist_table_length; distance_index++) {
> + int nodeA = numa_id_index_table[curr_row];
> + int nodeB = numa_id_index_table[curr_column++];
> +
> + numa_distance_table[nodeA][nodeB] = numa_dist_table[distance_index];
> +
> + pr_debug("dist[%d][%d]=%d ", nodeA, nodeB, numa_distance_table[nodeA][nodeB]);
> + if (curr_column >= max_numa_index) {
> + curr_row++;
> + /* reset the column */
> + curr_column = 0;
> + }
> + }
> }
>
> static int __init find_primary_domain_index(void)
> @@ -324,6 +453,9 @@ static int __init find_primary_domain_index(void)
> */
> if (firmware_has_feature(FW_FEATURE_OPAL)) {
> affinity_form = FORM1_AFFINITY;
> + } else if (firmware_has_feature(FW_FEATURE_FORM2_AFFINITY)) {
> + dbg("Using form 2 affinity\n");
> + affinity_form = FORM2_AFFINITY;
> } else if (firmware_has_feature(FW_FEATURE_FORM1_AFFINITY)) {
> dbg("Using form 1 affinity\n");
> affinity_form = FORM1_AFFINITY;
> @@ -368,8 +500,17 @@ static int __init find_primary_domain_index(void)
>
> index = of_read_number(&distance_ref_points[1], 1);
> } else {
> + /*
> + * Both FORM1 and FORM2 affinity find the primary domain details
> + * at the same offset.
> + */
> index = of_read_number(distance_ref_points, 1);
> }
> + /*
> + * If it is FORM2 also initialize the distance table here.
> + */
> + if (affinity_form == FORM2_AFFINITY)
> + initialize_form2_numa_distance_lookup_table(root);
>
> /*
> * Warn and cap if the hardware supports more than
> diff --git a/arch/powerpc/platforms/pseries/firmware.c b/arch/powerpc/platforms/pseries/firmware.c
> index 5d4c2bc20bba..f162156b7b68 100644
> --- a/arch/powerpc/platforms/pseries/firmware.c
> +++ b/arch/powerpc/platforms/pseries/firmware.c
> @@ -123,6 +123,7 @@ vec5_fw_features_table[] = {
> {FW_FEATURE_PRRN, OV5_PRRN},
> {FW_FEATURE_DRMEM_V2, OV5_DRMEM_V2},
> {FW_FEATURE_DRC_INFO, OV5_DRC_INFO},
> + {FW_FEATURE_FORM2_AFFINITY, OV5_FORM2_AFFINITY},
> };
>
> static void __init fw_vec5_feature_init(const char *vec5, unsigned long len)
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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