acpi, hmat: calculate abstract distance with HMAT

A memory tiering abstract distance calculation algorithm based on ACPI
HMAT is implemented.  The basic idea is as follows.

The performance attributes of system default DRAM nodes are recorded as
the base line.  Whose abstract distance is MEMTIER_ADISTANCE_DRAM.  Then,
the ratio of the abstract distance of a memory node (target) to
MEMTIER_ADISTANCE_DRAM is scaled based on the ratio of the performance
attributes of the node to that of the default DRAM nodes.

The functions to record the read/write latency/bandwidth of the default
DRAM nodes and calculate abstract distance according to read/write
latency/bandwidth ratio will be used by CXL CDAT (Coherent Device
Attribute Table) and other memory device drivers.  So, they are put in
memory-tiers.c.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: "Huang, Ying" <[email protected]>
Tested-by: Bharata B Rao <[email protected]>
Reviewed-by: Dave Jiang <[email protected]>
Reviewed-by: Alistair Popple <[email protected]>
Cc: Aneesh Kumar K.V <[email protected]>
Cc: Wei Xu <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Jonathan Cameron <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Yang Shi <[email protected]>
Cc: Rafael J Wysocki <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

1 files changed, 18 insertions, 0 deletions

diff --git a/include/linux/memory-tiers.h b/include/linux/memory-tiers.h
index fddc59990644..59d15c6d3c0d 100644
--- a/include/linux/memory-tiers.h
+++ b/include/linux/memory-tiers.h
@@ -31,8 +31,11 @@ struct memory_dev_type {
 	struct kref kref;
 };
 
+struct node_hmem_attrs;
+
 #ifdef CONFIG_NUMA
 extern bool numa_demotion_enabled;
+extern struct memory_dev_type *default_dram_type;
 struct memory_dev_type *alloc_memory_type(int adistance);
 void put_memory_type(struct memory_dev_type *memtype);
 void init_node_memory_type(int node, struct memory_dev_type *default_type);
@@ -40,6 +43,9 @@ void clear_node_memory_type(int node, struct memory_dev_type *memtype);
 int register_mt_adistance_algorithm(struct notifier_block *nb);
 int unregister_mt_adistance_algorithm(struct notifier_block *nb);
 int mt_calc_adistance(int node, int *adist);
+int mt_set_default_dram_perf(int nid, struct node_hmem_attrs *perf,
+			     const char *source);
+int mt_perf_to_adistance(struct node_hmem_attrs *perf, int *adist);
 #ifdef CONFIG_MIGRATION
 int next_demotion_node(int node);
 void node_get_allowed_targets(pg_data_t *pgdat, nodemask_t *targets);
@@ -64,6 +70,7 @@ static inline bool node_is_toptier(int node)
 #else
 
 #define numa_demotion_enabled	false
+#define default_dram_type	NULL
 /*
  * CONFIG_NUMA implementation returns non NULL error.
  */
@@ -116,5 +123,16 @@ static inline int mt_calc_adistance(int node, int *adist)
 {
 	return NOTIFY_DONE;
 }
+
+static inline int mt_set_default_dram_perf(int nid, struct node_hmem_attrs *perf,
+					   const char *source)
+{
+	return -EIO;
+}
+
+static inline int mt_perf_to_adistance(struct node_hmem_attrs *perf, int *adist)
+{
+	return -EIO;
+}
 #endif	/* CONFIG_NUMA */
 #endif  /* _LINUX_MEMORY_TIERS_H */