1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (C) 2016 Thomas Gleixner.
4 * Copyright (C) 2016-2017 Christoph Hellwig.
6 #include <linux/interrupt.h>
7 #include <linux/kernel.h>
8 #include <linux/slab.h>
11 static void irq_spread_init_one(struct cpumask *irqmsk, struct cpumask *nmsk,
12 unsigned int cpus_per_vec)
14 const struct cpumask *siblmsk;
17 for ( ; cpus_per_vec > 0; ) {
18 cpu = cpumask_first(nmsk);
20 /* Should not happen, but I'm too lazy to think about it */
21 if (cpu >= nr_cpu_ids)
24 cpumask_clear_cpu(cpu, nmsk);
25 cpumask_set_cpu(cpu, irqmsk);
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)
34 if (!cpumask_test_and_clear_cpu(sibl, nmsk))
36 cpumask_set_cpu(sibl, irqmsk);
42 static cpumask_var_t *alloc_node_to_cpumask(void)
47 masks = kcalloc(nr_node_ids, sizeof(cpumask_var_t), GFP_KERNEL);
51 for (node = 0; node < nr_node_ids; node++) {
52 if (!zalloc_cpumask_var(&masks[node], GFP_KERNEL))
60 free_cpumask_var(masks[node]);
65 static void free_node_to_cpumask(cpumask_var_t *masks)
69 for (node = 0; node < nr_node_ids; node++)
70 free_cpumask_var(masks[node]);
74 static void build_node_to_cpumask(cpumask_var_t *masks)
78 for_each_possible_cpu(cpu)
79 cpumask_set_cpu(cpu, masks[cpu_to_node(cpu)]);
82 static int get_nodes_in_cpumask(cpumask_var_t *node_to_cpumask,
83 const struct cpumask *mask, nodemask_t *nodemsk)
87 /* Calculate the number of nodes in the supplied affinity mask */
89 if (cpumask_intersects(mask, node_to_cpumask[n])) {
90 node_set(n, *nodemsk);
97 static int __irq_build_affinity_masks(unsigned int startvec,
99 unsigned int firstvec,
100 cpumask_var_t *node_to_cpumask,
101 const struct cpumask *cpu_mask,
102 struct cpumask *nmsk,
103 struct irq_affinity_desc *masks)
105 unsigned int n, nodes, cpus_per_vec, extra_vecs, done = 0;
106 unsigned int last_affv = firstvec + numvecs;
107 unsigned int curvec = startvec;
108 nodemask_t nodemsk = NODE_MASK_NONE;
110 if (!cpumask_weight(cpu_mask))
113 nodes = get_nodes_in_cpumask(node_to_cpumask, cpu_mask, &nodemsk);
116 * If the number of nodes in the mask is greater than or equal the
117 * number of vectors we just spread the vectors across the nodes.
119 if (numvecs <= nodes) {
120 for_each_node_mask(n, nodemsk) {
121 cpumask_or(&masks[curvec].mask, &masks[curvec].mask,
123 if (++curvec == last_affv)
129 for_each_node_mask(n, nodemsk) {
130 unsigned int ncpus, v, vecs_to_assign, vecs_per_node;
132 /* Spread the vectors per node */
133 vecs_per_node = (numvecs - (curvec - firstvec)) / nodes;
135 /* Get the cpus on this node which are in the mask */
136 cpumask_and(nmsk, cpu_mask, node_to_cpumask[n]);
138 /* Calculate the number of cpus per vector */
139 ncpus = cpumask_weight(nmsk);
140 vecs_to_assign = min(vecs_per_node, ncpus);
142 /* Account for rounding errors */
143 extra_vecs = ncpus - vecs_to_assign * (ncpus / vecs_to_assign);
145 for (v = 0; curvec < last_affv && v < vecs_to_assign;
147 cpus_per_vec = ncpus / vecs_to_assign;
149 /* Account for extra vectors to compensate rounding errors */
154 irq_spread_init_one(&masks[curvec].mask, nmsk,
161 if (curvec >= last_affv)
169 * build affinity in two stages:
170 * 1) spread present CPU on these vectors
171 * 2) spread other possible CPUs on these vectors
173 static int irq_build_affinity_masks(unsigned int startvec, unsigned int numvecs,
174 unsigned int firstvec,
175 struct irq_affinity_desc *masks)
177 unsigned int curvec = startvec, nr_present, nr_others;
178 cpumask_var_t *node_to_cpumask;
179 cpumask_var_t nmsk, npresmsk;
182 if (!zalloc_cpumask_var(&nmsk, GFP_KERNEL))
185 if (!zalloc_cpumask_var(&npresmsk, GFP_KERNEL))
188 node_to_cpumask = alloc_node_to_cpumask();
189 if (!node_to_cpumask)
193 /* Stabilize the cpumasks */
195 build_node_to_cpumask(node_to_cpumask);
197 /* Spread on present CPUs starting from affd->pre_vectors */
198 nr_present = __irq_build_affinity_masks(curvec, numvecs,
199 firstvec, node_to_cpumask,
200 cpu_present_mask, nmsk, masks);
203 * Spread on non present CPUs starting from the next vector to be
204 * handled. If the spreading of present CPUs already exhausted the
205 * vector space, assign the non present CPUs to the already spread
208 if (nr_present >= numvecs)
211 curvec = firstvec + nr_present;
212 cpumask_andnot(npresmsk, cpu_possible_mask, cpu_present_mask);
213 nr_others = __irq_build_affinity_masks(curvec, numvecs,
214 firstvec, node_to_cpumask,
215 npresmsk, nmsk, masks);
218 if (nr_present < numvecs)
219 WARN_ON(nr_present + nr_others < numvecs);
221 free_node_to_cpumask(node_to_cpumask);
224 free_cpumask_var(npresmsk);
227 free_cpumask_var(nmsk);
231 static void default_calc_sets(struct irq_affinity *affd, unsigned int affvecs)
234 affd->set_size[0] = affvecs;
238 * irq_create_affinity_masks - Create affinity masks for multiqueue spreading
239 * @nvecs: The total number of vectors
240 * @affd: Description of the affinity requirements
242 * Returns the irq_affinity_desc pointer or NULL if allocation failed.
244 struct irq_affinity_desc *
245 irq_create_affinity_masks(unsigned int nvecs, struct irq_affinity *affd)
247 unsigned int affvecs, curvec, usedvecs, i;
248 struct irq_affinity_desc *masks = NULL;
251 * Determine the number of vectors which need interrupt affinities
252 * assigned. If the pre/post request exhausts the available vectors
253 * then nothing to do here except for invoking the calc_sets()
254 * callback so the device driver can adjust to the situation. If there
255 * is only a single vector, then managing the queue is pointless as
258 if (nvecs > 1 && nvecs > affd->pre_vectors + affd->post_vectors)
259 affvecs = nvecs - affd->pre_vectors - affd->post_vectors;
264 * Simple invocations do not provide a calc_sets() callback. Install
267 if (!affd->calc_sets)
268 affd->calc_sets = default_calc_sets;
270 /* Recalculate the sets */
271 affd->calc_sets(affd, affvecs);
273 if (WARN_ON_ONCE(affd->nr_sets > IRQ_AFFINITY_MAX_SETS))
276 /* Nothing to assign? */
280 masks = kcalloc(nvecs, sizeof(*masks), GFP_KERNEL);
284 /* Fill out vectors at the beginning that don't need affinity */
285 for (curvec = 0; curvec < affd->pre_vectors; curvec++)
286 cpumask_copy(&masks[curvec].mask, irq_default_affinity);
289 * Spread on present CPUs starting from affd->pre_vectors. If we
290 * have multiple sets, build each sets affinity mask separately.
292 for (i = 0, usedvecs = 0; i < affd->nr_sets; i++) {
293 unsigned int this_vecs = affd->set_size[i];
296 ret = irq_build_affinity_masks(curvec, this_vecs,
303 usedvecs += this_vecs;
306 /* Fill out vectors at the end that don't need affinity */
307 if (usedvecs >= affvecs)
308 curvec = affd->pre_vectors + affvecs;
310 curvec = affd->pre_vectors + usedvecs;
311 for (; curvec < nvecs; curvec++)
312 cpumask_copy(&masks[curvec].mask, irq_default_affinity);
314 /* Mark the managed interrupts */
315 for (i = affd->pre_vectors; i < nvecs - affd->post_vectors; i++)
316 masks[i].is_managed = 1;
322 * irq_calc_affinity_vectors - Calculate the optimal number of vectors
323 * @minvec: The minimum number of vectors available
324 * @maxvec: The maximum number of vectors available
325 * @affd: Description of the affinity requirements
327 unsigned int irq_calc_affinity_vectors(unsigned int minvec, unsigned int maxvec,
328 const struct irq_affinity *affd)
330 unsigned int resv = affd->pre_vectors + affd->post_vectors;
331 unsigned int set_vecs;
336 if (affd->calc_sets) {
337 set_vecs = maxvec - resv;
340 set_vecs = cpumask_weight(cpu_possible_mask);
344 return resv + min(set_vecs, maxvec - resv);