1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 2016 Thomas Gleixner. 4 * Copyright (C) 2016-2017 Christoph Hellwig. 5 */ 6 #include <linux/interrupt.h> 7 #include <linux/kernel.h> 8 #include <linux/slab.h> 9 #include <linux/cpu.h> 10 11 static void irq_spread_init_one(struct cpumask *irqmsk, struct cpumask *nmsk, 12 int cpus_per_vec) 13 { 14 const struct cpumask *siblmsk; 15 int cpu, sibl; 16 17 for ( ; cpus_per_vec > 0; ) { 18 cpu = cpumask_first(nmsk); 19 20 /* Should not happen, but I'm too lazy to think about it */ 21 if (cpu >= nr_cpu_ids) 22 return; 23 24 cpumask_clear_cpu(cpu, nmsk); 25 cpumask_set_cpu(cpu, irqmsk); 26 cpus_per_vec--; 27 28 /* If the cpu has siblings, use them first */ 29 siblmsk = topology_sibling_cpumask(cpu); 30 for (sibl = -1; cpus_per_vec > 0; ) { 31 sibl = cpumask_next(sibl, siblmsk); 32 if (sibl >= nr_cpu_ids) 33 break; 34 if (!cpumask_test_and_clear_cpu(sibl, nmsk)) 35 continue; 36 cpumask_set_cpu(sibl, irqmsk); 37 cpus_per_vec--; 38 } 39 } 40 } 41 42 static cpumask_var_t *alloc_node_to_possible_cpumask(void) 43 { 44 cpumask_var_t *masks; 45 int node; 46 47 masks = kcalloc(nr_node_ids, sizeof(cpumask_var_t), GFP_KERNEL); 48 if (!masks) 49 return NULL; 50 51 for (node = 0; node < nr_node_ids; node++) { 52 if (!zalloc_cpumask_var(&masks[node], GFP_KERNEL)) 53 goto out_unwind; 54 } 55 56 return masks; 57 58 out_unwind: 59 while (--node >= 0) 60 free_cpumask_var(masks[node]); 61 kfree(masks); 62 return NULL; 63 } 64 65 static void free_node_to_possible_cpumask(cpumask_var_t *masks) 66 { 67 int node; 68 69 for (node = 0; node < nr_node_ids; node++) 70 free_cpumask_var(masks[node]); 71 kfree(masks); 72 } 73 74 static void build_node_to_possible_cpumask(cpumask_var_t *masks) 75 { 76 int cpu; 77 78 for_each_possible_cpu(cpu) 79 cpumask_set_cpu(cpu, masks[cpu_to_node(cpu)]); 80 } 81 82 static int get_nodes_in_cpumask(cpumask_var_t *node_to_possible_cpumask, 83 const struct cpumask *mask, nodemask_t *nodemsk) 84 { 85 int n, nodes = 0; 86 87 /* Calculate the number of nodes in the supplied affinity mask */ 88 for_each_node(n) { 89 if (cpumask_intersects(mask, node_to_possible_cpumask[n])) { 90 node_set(n, *nodemsk); 91 nodes++; 92 } 93 } 94 return nodes; 95 } 96 97 /** 98 * irq_create_affinity_masks - Create affinity masks for multiqueue spreading 99 * @nvecs: The total number of vectors 100 * @affd: Description of the affinity requirements 101 * 102 * Returns the masks pointer or NULL if allocation failed. 103 */ 104 struct cpumask * 105 irq_create_affinity_masks(int nvecs, const struct irq_affinity *affd) 106 { 107 int n, nodes, cpus_per_vec, extra_vecs, curvec; 108 int affv = nvecs - affd->pre_vectors - affd->post_vectors; 109 int last_affv = affv + affd->pre_vectors; 110 nodemask_t nodemsk = NODE_MASK_NONE; 111 struct cpumask *masks; 112 cpumask_var_t nmsk, *node_to_possible_cpumask; 113 114 /* 115 * If there aren't any vectors left after applying the pre/post 116 * vectors don't bother with assigning affinity. 117 */ 118 if (!affv) 119 return NULL; 120 121 if (!zalloc_cpumask_var(&nmsk, GFP_KERNEL)) 122 return NULL; 123 124 masks = kcalloc(nvecs, sizeof(*masks), GFP_KERNEL); 125 if (!masks) 126 goto out; 127 128 node_to_possible_cpumask = alloc_node_to_possible_cpumask(); 129 if (!node_to_possible_cpumask) 130 goto out; 131 132 /* Fill out vectors at the beginning that don't need affinity */ 133 for (curvec = 0; curvec < affd->pre_vectors; curvec++) 134 cpumask_copy(masks + curvec, irq_default_affinity); 135 136 /* Stabilize the cpumasks */ 137 get_online_cpus(); 138 build_node_to_possible_cpumask(node_to_possible_cpumask); 139 nodes = get_nodes_in_cpumask(node_to_possible_cpumask, cpu_possible_mask, 140 &nodemsk); 141 142 /* 143 * If the number of nodes in the mask is greater than or equal the 144 * number of vectors we just spread the vectors across the nodes. 145 */ 146 if (affv <= nodes) { 147 for_each_node_mask(n, nodemsk) { 148 cpumask_copy(masks + curvec, 149 node_to_possible_cpumask[n]); 150 if (++curvec == last_affv) 151 break; 152 } 153 goto done; 154 } 155 156 for_each_node_mask(n, nodemsk) { 157 int ncpus, v, vecs_to_assign, vecs_per_node; 158 159 /* Spread the vectors per node */ 160 vecs_per_node = (affv - (curvec - affd->pre_vectors)) / nodes; 161 162 /* Get the cpus on this node which are in the mask */ 163 cpumask_and(nmsk, cpu_possible_mask, node_to_possible_cpumask[n]); 164 165 /* Calculate the number of cpus per vector */ 166 ncpus = cpumask_weight(nmsk); 167 vecs_to_assign = min(vecs_per_node, ncpus); 168 169 /* Account for rounding errors */ 170 extra_vecs = ncpus - vecs_to_assign * (ncpus / vecs_to_assign); 171 172 for (v = 0; curvec < last_affv && v < vecs_to_assign; 173 curvec++, v++) { 174 cpus_per_vec = ncpus / vecs_to_assign; 175 176 /* Account for extra vectors to compensate rounding errors */ 177 if (extra_vecs) { 178 cpus_per_vec++; 179 --extra_vecs; 180 } 181 irq_spread_init_one(masks + curvec, nmsk, cpus_per_vec); 182 } 183 184 if (curvec >= last_affv) 185 break; 186 --nodes; 187 } 188 189 done: 190 put_online_cpus(); 191 192 /* Fill out vectors at the end that don't need affinity */ 193 for (; curvec < nvecs; curvec++) 194 cpumask_copy(masks + curvec, irq_default_affinity); 195 free_node_to_possible_cpumask(node_to_possible_cpumask); 196 out: 197 free_cpumask_var(nmsk); 198 return masks; 199 } 200 201 /** 202 * irq_calc_affinity_vectors - Calculate the optimal number of vectors 203 * @minvec: The minimum number of vectors available 204 * @maxvec: The maximum number of vectors available 205 * @affd: Description of the affinity requirements 206 */ 207 int irq_calc_affinity_vectors(int minvec, int maxvec, const struct irq_affinity *affd) 208 { 209 int resv = affd->pre_vectors + affd->post_vectors; 210 int vecs = maxvec - resv; 211 int ret; 212 213 if (resv > minvec) 214 return 0; 215 216 get_online_cpus(); 217 ret = min_t(int, cpumask_weight(cpu_possible_mask), vecs) + resv; 218 put_online_cpus(); 219 return ret; 220 } 221