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6a954e94d0
Dan Williams suggested changing the struct 'node_hmem_attrs' to 'access_coordinates' [1]. The struct is a container of r/w-latency and r/w-bandwidth numbers. Moving forward, this container will also be used by CXL to store the performance characteristics of each link hop in the PCIE/CXL topology. So, where node_hmem_attrs is just the access parameters of a memory-node, access_coordinates applies more broadly to hardware topology characteristics. The observation is that seemed like an exercise in having the application identify "where" it falls on a spectrum of bandwidth and latency needs. For the tuple of read/write-latency and read/write-bandwidth, "coordinates" is not a perfect fit. Sometimes it is just conveying values in isolation and not a "location" relative to other performance points, but in the end this data is used to identify the performance operation point of a given memory-node. [2] Link: http://lore.kernel.org/r/64471313421f7_1b66294d5@dwillia2-xfh.jf.intel.com.notmuch/ Link: https://lore.kernel.org/linux-cxl/645e6215ee0de_1e6f2945e@dwillia2-xfh.jf.intel.com.notmuch/ Suggested-by: Dan Williams <dan.j.williams@intel.com> Reviewed-by: Dan Williams <dan.j.williams@intel.com> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Signed-off-by: Dave Jiang <dave.jiang@intel.com> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Link: https://lore.kernel.org/r/170319615734.2212653.15319394025985499185.stgit@djiang5-mobl3 Signed-off-by: Dan Williams <dan.j.williams@intel.com>
141 lines
3.5 KiB
C
141 lines
3.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_MEMORY_TIERS_H
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#define _LINUX_MEMORY_TIERS_H
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#include <linux/types.h>
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#include <linux/nodemask.h>
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#include <linux/kref.h>
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#include <linux/mmzone.h>
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#include <linux/notifier.h>
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/*
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* Each tier cover a abstrace distance chunk size of 128
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*/
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#define MEMTIER_CHUNK_BITS 7
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#define MEMTIER_CHUNK_SIZE (1 << MEMTIER_CHUNK_BITS)
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/*
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* Smaller abstract distance values imply faster (higher) memory tiers. Offset
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* the DRAM adistance so that we can accommodate devices with a slightly lower
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* adistance value (slightly faster) than default DRAM adistance to be part of
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* the same memory tier.
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*/
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#define MEMTIER_ADISTANCE_DRAM ((4 * MEMTIER_CHUNK_SIZE) + (MEMTIER_CHUNK_SIZE >> 1))
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struct memory_tier;
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struct memory_dev_type {
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/* list of memory types that are part of same tier as this type */
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struct list_head tier_sibling;
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/* list of memory types that are managed by one driver */
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struct list_head list;
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/* abstract distance for this specific memory type */
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int adistance;
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/* Nodes of same abstract distance */
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nodemask_t nodes;
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struct kref kref;
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};
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struct access_coordinate;
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#ifdef CONFIG_NUMA
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extern bool numa_demotion_enabled;
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extern struct memory_dev_type *default_dram_type;
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struct memory_dev_type *alloc_memory_type(int adistance);
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void put_memory_type(struct memory_dev_type *memtype);
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void init_node_memory_type(int node, struct memory_dev_type *default_type);
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void clear_node_memory_type(int node, struct memory_dev_type *memtype);
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int register_mt_adistance_algorithm(struct notifier_block *nb);
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int unregister_mt_adistance_algorithm(struct notifier_block *nb);
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int mt_calc_adistance(int node, int *adist);
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int mt_set_default_dram_perf(int nid, struct access_coordinate *perf,
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const char *source);
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int mt_perf_to_adistance(struct access_coordinate *perf, int *adist);
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#ifdef CONFIG_MIGRATION
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int next_demotion_node(int node);
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void node_get_allowed_targets(pg_data_t *pgdat, nodemask_t *targets);
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bool node_is_toptier(int node);
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#else
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static inline int next_demotion_node(int node)
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{
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return NUMA_NO_NODE;
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}
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static inline void node_get_allowed_targets(pg_data_t *pgdat, nodemask_t *targets)
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{
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*targets = NODE_MASK_NONE;
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}
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static inline bool node_is_toptier(int node)
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{
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return true;
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}
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#endif
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#else
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#define numa_demotion_enabled false
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#define default_dram_type NULL
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/*
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* CONFIG_NUMA implementation returns non NULL error.
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*/
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static inline struct memory_dev_type *alloc_memory_type(int adistance)
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{
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return NULL;
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}
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static inline void put_memory_type(struct memory_dev_type *memtype)
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{
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}
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static inline void init_node_memory_type(int node, struct memory_dev_type *default_type)
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{
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}
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static inline void clear_node_memory_type(int node, struct memory_dev_type *memtype)
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{
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}
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static inline int next_demotion_node(int node)
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{
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return NUMA_NO_NODE;
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}
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static inline void node_get_allowed_targets(pg_data_t *pgdat, nodemask_t *targets)
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{
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*targets = NODE_MASK_NONE;
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}
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static inline bool node_is_toptier(int node)
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{
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return true;
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}
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static inline int register_mt_adistance_algorithm(struct notifier_block *nb)
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{
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return 0;
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}
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static inline int unregister_mt_adistance_algorithm(struct notifier_block *nb)
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{
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return 0;
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}
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static inline int mt_calc_adistance(int node, int *adist)
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{
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return NOTIFY_DONE;
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}
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static inline int mt_set_default_dram_perf(int nid, struct access_coordinate *perf,
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const char *source)
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{
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return -EIO;
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}
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static inline int mt_perf_to_adistance(struct access_coordinate *perf, int *adist)
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{
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return -EIO;
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}
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#endif /* CONFIG_NUMA */
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#endif /* _LINUX_MEMORY_TIERS_H */
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