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Diffstat (limited to 'arch/s390/numa/mode_emu.c')
| -rw-r--r-- | arch/s390/numa/mode_emu.c | 576 |
1 files changed, 576 insertions, 0 deletions
diff --git a/arch/s390/numa/mode_emu.c b/arch/s390/numa/mode_emu.c new file mode 100644 index 000000000..83b222c57 --- /dev/null +++ b/arch/s390/numa/mode_emu.c @@ -0,0 +1,576 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * NUMA support for s390 + * + * NUMA emulation (aka fake NUMA) distributes the available memory to nodes + * without using real topology information about the physical memory of the + * machine. + * + * It distributes the available CPUs to nodes while respecting the original + * machine topology information. This is done by trying to avoid to separate + * CPUs which reside on the same book or even on the same MC. + * + * Because the current Linux scheduler code requires a stable cpu to node + * mapping, cores are pinned to nodes when the first CPU thread is set online. + * + * Copyright IBM Corp. 2015 + */ + +#define KMSG_COMPONENT "numa_emu" +#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt + +#include <linux/kernel.h> +#include <linux/cpumask.h> +#include <linux/memblock.h> +#include <linux/bootmem.h> +#include <linux/node.h> +#include <linux/memory.h> +#include <linux/slab.h> +#include <asm/smp.h> +#include <asm/topology.h> +#include "numa_mode.h" +#include "toptree.h" + +/* Distances between the different system components */ +#define DIST_EMPTY 0 +#define DIST_CORE 1 +#define DIST_MC 2 +#define DIST_BOOK 3 +#define DIST_DRAWER 4 +#define DIST_MAX 5 + +/* Node distance reported to common code */ +#define EMU_NODE_DIST 10 + +/* Node ID for free (not yet pinned) cores */ +#define NODE_ID_FREE -1 + +/* Different levels of toptree */ +enum toptree_level {CORE, MC, BOOK, DRAWER, NODE, TOPOLOGY}; + +/* The two toptree IDs */ +enum {TOPTREE_ID_PHYS, TOPTREE_ID_NUMA}; + +/* Number of NUMA nodes */ +static int emu_nodes = 1; +/* NUMA stripe size */ +static unsigned long emu_size; + +/* + * Node to core pinning information updates are protected by + * "sched_domains_mutex". + */ +static struct { + s32 to_node_id[CONFIG_NR_CPUS]; /* Pinned core to node mapping */ + int total; /* Total number of pinned cores */ + int per_node_target; /* Cores per node without extra cores */ + int per_node[MAX_NUMNODES]; /* Number of cores pinned to node */ +} *emu_cores; + +/* + * Pin a core to a node + */ +static void pin_core_to_node(int core_id, int node_id) +{ + if (emu_cores->to_node_id[core_id] == NODE_ID_FREE) { + emu_cores->per_node[node_id]++; + emu_cores->to_node_id[core_id] = node_id; + emu_cores->total++; + } else { + WARN_ON(emu_cores->to_node_id[core_id] != node_id); + } +} + +/* + * Number of pinned cores of a node + */ +static int cores_pinned(struct toptree *node) +{ + return emu_cores->per_node[node->id]; +} + +/* + * ID of the node where the core is pinned (or NODE_ID_FREE) + */ +static int core_pinned_to_node_id(struct toptree *core) +{ + return emu_cores->to_node_id[core->id]; +} + +/* + * Number of cores in the tree that are not yet pinned + */ +static int cores_free(struct toptree *tree) +{ + struct toptree *core; + int count = 0; + + toptree_for_each(core, tree, CORE) { + if (core_pinned_to_node_id(core) == NODE_ID_FREE) + count++; + } + return count; +} + +/* + * Return node of core + */ +static struct toptree *core_node(struct toptree *core) +{ + return core->parent->parent->parent->parent; +} + +/* + * Return drawer of core + */ +static struct toptree *core_drawer(struct toptree *core) +{ + return core->parent->parent->parent; +} + +/* + * Return book of core + */ +static struct toptree *core_book(struct toptree *core) +{ + return core->parent->parent; +} + +/* + * Return mc of core + */ +static struct toptree *core_mc(struct toptree *core) +{ + return core->parent; +} + +/* + * Distance between two cores + */ +static int dist_core_to_core(struct toptree *core1, struct toptree *core2) +{ + if (core_drawer(core1)->id != core_drawer(core2)->id) + return DIST_DRAWER; + if (core_book(core1)->id != core_book(core2)->id) + return DIST_BOOK; + if (core_mc(core1)->id != core_mc(core2)->id) + return DIST_MC; + /* Same core or sibling on same MC */ + return DIST_CORE; +} + +/* + * Distance of a node to a core + */ +static int dist_node_to_core(struct toptree *node, struct toptree *core) +{ + struct toptree *core_node; + int dist_min = DIST_MAX; + + toptree_for_each(core_node, node, CORE) + dist_min = min(dist_min, dist_core_to_core(core_node, core)); + return dist_min == DIST_MAX ? DIST_EMPTY : dist_min; +} + +/* + * Unify will delete empty nodes, therefore recreate nodes. + */ +static void toptree_unify_tree(struct toptree *tree) +{ + int nid; + + toptree_unify(tree); + for (nid = 0; nid < emu_nodes; nid++) + toptree_get_child(tree, nid); +} + +/* + * Find the best/nearest node for a given core and ensure that no node + * gets more than "emu_cores->per_node_target + extra" cores. + */ +static struct toptree *node_for_core(struct toptree *numa, struct toptree *core, + int extra) +{ + struct toptree *node, *node_best = NULL; + int dist_cur, dist_best, cores_target; + + cores_target = emu_cores->per_node_target + extra; + dist_best = DIST_MAX; + node_best = NULL; + toptree_for_each(node, numa, NODE) { + /* Already pinned cores must use their nodes */ + if (core_pinned_to_node_id(core) == node->id) { + node_best = node; + break; + } + /* Skip nodes that already have enough cores */ + if (cores_pinned(node) >= cores_target) + continue; + dist_cur = dist_node_to_core(node, core); + if (dist_cur < dist_best) { + dist_best = dist_cur; + node_best = node; + } + } + return node_best; +} + +/* + * Find the best node for each core with respect to "extra" core count + */ +static void toptree_to_numa_single(struct toptree *numa, struct toptree *phys, + int extra) +{ + struct toptree *node, *core, *tmp; + + toptree_for_each_safe(core, tmp, phys, CORE) { + node = node_for_core(numa, core, extra); + if (!node) + return; + toptree_move(core, node); + pin_core_to_node(core->id, node->id); + } +} + +/* + * Move structures of given level to specified NUMA node + */ +static void move_level_to_numa_node(struct toptree *node, struct toptree *phys, + enum toptree_level level, bool perfect) +{ + int cores_free, cores_target = emu_cores->per_node_target; + struct toptree *cur, *tmp; + + toptree_for_each_safe(cur, tmp, phys, level) { + cores_free = cores_target - toptree_count(node, CORE); + if (perfect) { + if (cores_free == toptree_count(cur, CORE)) + toptree_move(cur, node); + } else { + if (cores_free >= toptree_count(cur, CORE)) + toptree_move(cur, node); + } + } +} + +/* + * Move structures of a given level to NUMA nodes. If "perfect" is specified + * move only perfectly fitting structures. Otherwise move also smaller + * than needed structures. + */ +static void move_level_to_numa(struct toptree *numa, struct toptree *phys, + enum toptree_level level, bool perfect) +{ + struct toptree *node; + + toptree_for_each(node, numa, NODE) + move_level_to_numa_node(node, phys, level, perfect); +} + +/* + * For the first run try to move the big structures + */ +static void toptree_to_numa_first(struct toptree *numa, struct toptree *phys) +{ + struct toptree *core; + + /* Always try to move perfectly fitting structures first */ + move_level_to_numa(numa, phys, DRAWER, true); + move_level_to_numa(numa, phys, DRAWER, false); + move_level_to_numa(numa, phys, BOOK, true); + move_level_to_numa(numa, phys, BOOK, false); + move_level_to_numa(numa, phys, MC, true); + move_level_to_numa(numa, phys, MC, false); + /* Now pin all the moved cores */ + toptree_for_each(core, numa, CORE) + pin_core_to_node(core->id, core_node(core)->id); +} + +/* + * Allocate new topology and create required nodes + */ +static struct toptree *toptree_new(int id, int nodes) +{ + struct toptree *tree; + int nid; + + tree = toptree_alloc(TOPOLOGY, id); + if (!tree) + goto fail; + for (nid = 0; nid < nodes; nid++) { + if (!toptree_get_child(tree, nid)) + goto fail; + } + return tree; +fail: + panic("NUMA emulation could not allocate topology"); +} + +/* + * Allocate and initialize core to node mapping + */ +static void __ref create_core_to_node_map(void) +{ + int i; + + emu_cores = memblock_virt_alloc(sizeof(*emu_cores), 8); + for (i = 0; i < ARRAY_SIZE(emu_cores->to_node_id); i++) + emu_cores->to_node_id[i] = NODE_ID_FREE; +} + +/* + * Move cores from physical topology into NUMA target topology + * and try to keep as much of the physical topology as possible. + */ +static struct toptree *toptree_to_numa(struct toptree *phys) +{ + static int first = 1; + struct toptree *numa; + int cores_total; + + cores_total = emu_cores->total + cores_free(phys); + emu_cores->per_node_target = cores_total / emu_nodes; + numa = toptree_new(TOPTREE_ID_NUMA, emu_nodes); + if (first) { + toptree_to_numa_first(numa, phys); + first = 0; + } + toptree_to_numa_single(numa, phys, 0); + toptree_to_numa_single(numa, phys, 1); + toptree_unify_tree(numa); + + WARN_ON(cpumask_weight(&phys->mask)); + return numa; +} + +/* + * Create a toptree out of the physical topology that we got from the hypervisor + */ +static struct toptree *toptree_from_topology(void) +{ + struct toptree *phys, *node, *drawer, *book, *mc, *core; + struct cpu_topology_s390 *top; + int cpu; + + phys = toptree_new(TOPTREE_ID_PHYS, 1); + + for_each_cpu(cpu, &cpus_with_topology) { + top = &cpu_topology[cpu]; + node = toptree_get_child(phys, 0); + drawer = toptree_get_child(node, top->drawer_id); + book = toptree_get_child(drawer, top->book_id); + mc = toptree_get_child(book, top->socket_id); + core = toptree_get_child(mc, smp_get_base_cpu(cpu)); + if (!drawer || !book || !mc || !core) + panic("NUMA emulation could not allocate memory"); + cpumask_set_cpu(cpu, &core->mask); + toptree_update_mask(mc); + } + return phys; +} + +/* + * Add toptree core to topology and create correct CPU masks + */ +static void topology_add_core(struct toptree *core) +{ + struct cpu_topology_s390 *top; + int cpu; + + for_each_cpu(cpu, &core->mask) { + top = &cpu_topology[cpu]; + cpumask_copy(&top->thread_mask, &core->mask); + cpumask_copy(&top->core_mask, &core_mc(core)->mask); + cpumask_copy(&top->book_mask, &core_book(core)->mask); + cpumask_copy(&top->drawer_mask, &core_drawer(core)->mask); + cpumask_set_cpu(cpu, &node_to_cpumask_map[core_node(core)->id]); + top->node_id = core_node(core)->id; + } +} + +/* + * Apply toptree to topology and create CPU masks + */ +static void toptree_to_topology(struct toptree *numa) +{ + struct toptree *core; + int i; + + /* Clear all node masks */ + for (i = 0; i < MAX_NUMNODES; i++) + cpumask_clear(&node_to_cpumask_map[i]); + + /* Rebuild all masks */ + toptree_for_each(core, numa, CORE) + topology_add_core(core); +} + +/* + * Show the node to core mapping + */ +static void print_node_to_core_map(void) +{ + int nid, cid; + + if (!numa_debug_enabled) + return; + printk(KERN_DEBUG "NUMA node to core mapping\n"); + for (nid = 0; nid < emu_nodes; nid++) { + printk(KERN_DEBUG " node %3d: ", nid); + for (cid = 0; cid < ARRAY_SIZE(emu_cores->to_node_id); cid++) { + if (emu_cores->to_node_id[cid] == nid) + printk(KERN_CONT "%d ", cid); + } + printk(KERN_CONT "\n"); + } +} + +static void pin_all_possible_cpus(void) +{ + int core_id, node_id, cpu; + static int initialized; + + if (initialized) + return; + print_node_to_core_map(); + node_id = 0; + for_each_possible_cpu(cpu) { + core_id = smp_get_base_cpu(cpu); + if (emu_cores->to_node_id[core_id] != NODE_ID_FREE) + continue; + pin_core_to_node(core_id, node_id); + cpu_topology[cpu].node_id = node_id; + node_id = (node_id + 1) % emu_nodes; + } + print_node_to_core_map(); + initialized = 1; +} + +/* + * Transfer physical topology into a NUMA topology and modify CPU masks + * according to the NUMA topology. + * + * Must be called with "sched_domains_mutex" lock held. + */ +static void emu_update_cpu_topology(void) +{ + struct toptree *phys, *numa; + + if (emu_cores == NULL) + create_core_to_node_map(); + phys = toptree_from_topology(); + numa = toptree_to_numa(phys); + toptree_free(phys); + toptree_to_topology(numa); + toptree_free(numa); + pin_all_possible_cpus(); +} + +/* + * If emu_size is not set, use CONFIG_EMU_SIZE. Then round to minimum + * alignment (needed for memory hotplug). + */ +static unsigned long emu_setup_size_adjust(unsigned long size) +{ + unsigned long size_new; + + size = size ? : CONFIG_EMU_SIZE; + size_new = roundup(size, memory_block_size_bytes()); + if (size_new == size) + return size; + pr_warn("Increasing memory stripe size from %ld MB to %ld MB\n", + size >> 20, size_new >> 20); + return size_new; +} + +/* + * If we have not enough memory for the specified nodes, reduce the node count. + */ +static int emu_setup_nodes_adjust(int nodes) +{ + int nodes_max; + + nodes_max = memblock.memory.total_size / emu_size; + nodes_max = max(nodes_max, 1); + if (nodes_max >= nodes) + return nodes; + pr_warn("Not enough memory for %d nodes, reducing node count\n", nodes); + return nodes_max; +} + +/* + * Early emu setup + */ +static void emu_setup(void) +{ + int nid; + + emu_size = emu_setup_size_adjust(emu_size); + emu_nodes = emu_setup_nodes_adjust(emu_nodes); + for (nid = 0; nid < emu_nodes; nid++) + node_set(nid, node_possible_map); + pr_info("Creating %d nodes with memory stripe size %ld MB\n", + emu_nodes, emu_size >> 20); +} + +/* + * Return node id for given page number + */ +static int emu_pfn_to_nid(unsigned long pfn) +{ + return (pfn / (emu_size >> PAGE_SHIFT)) % emu_nodes; +} + +/* + * Return stripe size + */ +static unsigned long emu_align(void) +{ + return emu_size; +} + +/* + * Return distance between two nodes + */ +static int emu_distance(int node1, int node2) +{ + return (node1 != node2) * EMU_NODE_DIST; +} + +/* + * Define callbacks for generic s390 NUMA infrastructure + */ +const struct numa_mode numa_mode_emu = { + .name = "emu", + .setup = emu_setup, + .update_cpu_topology = emu_update_cpu_topology, + .__pfn_to_nid = emu_pfn_to_nid, + .align = emu_align, + .distance = emu_distance, +}; + +/* + * Kernel parameter: emu_nodes=<n> + */ +static int __init early_parse_emu_nodes(char *p) +{ + int count; + + if (kstrtoint(p, 0, &count) != 0 || count <= 0) + return 0; + if (count <= 0) + return 0; + emu_nodes = min(count, MAX_NUMNODES); + return 0; +} +early_param("emu_nodes", early_parse_emu_nodes); + +/* + * Kernel parameter: emu_size=[<n>[k|M|G|T]] + */ +static int __init early_parse_emu_size(char *p) +{ + emu_size = memparse(p, NULL); + return 0; +} +early_param("emu_size", early_parse_emu_size); |