// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2016 Thomas Gleixner.
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* Copyright (C) 2016-2017 Christoph Hellwig.
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*/
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#include <linux/interrupt.h>
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include <linux/cpu.h>
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#include <linux/sort.h>
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static void irq_spread_init_one(struct cpumask *irqmsk, struct cpumask *nmsk,
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unsigned int cpus_per_vec)
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{
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const struct cpumask *siblmsk;
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int cpu, sibl;
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for ( ; cpus_per_vec > 0; ) {
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cpu = cpumask_first(nmsk);
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/* Should not happen, but I'm too lazy to think about it */
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if (cpu >= nr_cpu_ids)
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return;
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cpumask_clear_cpu(cpu, nmsk);
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cpumask_set_cpu(cpu, irqmsk);
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cpus_per_vec--;
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/* If the cpu has siblings, use them first */
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siblmsk = topology_sibling_cpumask(cpu);
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for (sibl = -1; cpus_per_vec > 0; ) {
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sibl = cpumask_next(sibl, siblmsk);
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if (sibl >= nr_cpu_ids)
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break;
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if (!cpumask_test_and_clear_cpu(sibl, nmsk))
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continue;
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cpumask_set_cpu(sibl, irqmsk);
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cpus_per_vec--;
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}
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}
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}
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static cpumask_var_t *alloc_node_to_cpumask(void)
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{
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cpumask_var_t *masks;
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int node;
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masks = kcalloc(nr_node_ids, sizeof(cpumask_var_t), GFP_KERNEL);
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if (!masks)
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return NULL;
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for (node = 0; node < nr_node_ids; node++) {
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if (!zalloc_cpumask_var(&masks[node], GFP_KERNEL))
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goto out_unwind;
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}
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return masks;
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out_unwind:
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while (--node >= 0)
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free_cpumask_var(masks[node]);
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kfree(masks);
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return NULL;
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}
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static void free_node_to_cpumask(cpumask_var_t *masks)
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{
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int node;
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for (node = 0; node < nr_node_ids; node++)
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free_cpumask_var(masks[node]);
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kfree(masks);
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}
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static void build_node_to_cpumask(cpumask_var_t *masks)
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{
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int cpu;
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for_each_possible_cpu(cpu)
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cpumask_set_cpu(cpu, masks[cpu_to_node(cpu)]);
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}
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static int get_nodes_in_cpumask(cpumask_var_t *node_to_cpumask,
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const struct cpumask *mask, nodemask_t *nodemsk)
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{
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int n, nodes = 0;
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/* Calculate the number of nodes in the supplied affinity mask */
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for_each_node(n) {
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if (cpumask_intersects(mask, node_to_cpumask[n])) {
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node_set(n, *nodemsk);
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nodes++;
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}
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}
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return nodes;
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}
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struct node_vectors {
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unsigned id;
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union {
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unsigned nvectors;
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unsigned ncpus;
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};
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};
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static int ncpus_cmp_func(const void *l, const void *r)
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{
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const struct node_vectors *ln = l;
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const struct node_vectors *rn = r;
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return ln->ncpus - rn->ncpus;
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}
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/*
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* Allocate vector number for each node, so that for each node:
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*
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* 1) the allocated number is >= 1
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*
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* 2) the allocated numbver is <= active CPU number of this node
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*
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* The actual allocated total vectors may be less than @numvecs when
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* active total CPU number is less than @numvecs.
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*
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* Active CPUs means the CPUs in '@cpu_mask AND @node_to_cpumask[]'
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* for each node.
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*/
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static void alloc_nodes_vectors(unsigned int numvecs,
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cpumask_var_t *node_to_cpumask,
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const struct cpumask *cpu_mask,
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const nodemask_t nodemsk,
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struct cpumask *nmsk,
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struct node_vectors *node_vectors)
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{
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unsigned n, remaining_ncpus = 0;
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for (n = 0; n < nr_node_ids; n++) {
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node_vectors[n].id = n;
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node_vectors[n].ncpus = UINT_MAX;
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}
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for_each_node_mask(n, nodemsk) {
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unsigned ncpus;
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cpumask_and(nmsk, cpu_mask, node_to_cpumask[n]);
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ncpus = cpumask_weight(nmsk);
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if (!ncpus)
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continue;
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remaining_ncpus += ncpus;
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node_vectors[n].ncpus = ncpus;
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}
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numvecs = min_t(unsigned, remaining_ncpus, numvecs);
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sort(node_vectors, nr_node_ids, sizeof(node_vectors[0]),
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ncpus_cmp_func, NULL);
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/*
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* Allocate vectors for each node according to the ratio of this
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* node's nr_cpus to remaining un-assigned ncpus. 'numvecs' is
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* bigger than number of active numa nodes. Always start the
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* allocation from the node with minimized nr_cpus.
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*
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* This way guarantees that each active node gets allocated at
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* least one vector, and the theory is simple: over-allocation
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* is only done when this node is assigned by one vector, so
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* other nodes will be allocated >= 1 vector, since 'numvecs' is
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* bigger than number of numa nodes.
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*
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* One perfect invariant is that number of allocated vectors for
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* each node is <= CPU count of this node:
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*
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* 1) suppose there are two nodes: A and B
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* ncpu(X) is CPU count of node X
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* vecs(X) is the vector count allocated to node X via this
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* algorithm
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*
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* ncpu(A) <= ncpu(B)
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* ncpu(A) + ncpu(B) = N
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* vecs(A) + vecs(B) = V
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*
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* vecs(A) = max(1, round_down(V * ncpu(A) / N))
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* vecs(B) = V - vecs(A)
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*
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* both N and V are integer, and 2 <= V <= N, suppose
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* V = N - delta, and 0 <= delta <= N - 2
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*
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* 2) obviously vecs(A) <= ncpu(A) because:
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*
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* if vecs(A) is 1, then vecs(A) <= ncpu(A) given
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* ncpu(A) >= 1
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*
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* otherwise,
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* vecs(A) <= V * ncpu(A) / N <= ncpu(A), given V <= N
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*
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* 3) prove how vecs(B) <= ncpu(B):
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*
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* if round_down(V * ncpu(A) / N) == 0, vecs(B) won't be
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* over-allocated, so vecs(B) <= ncpu(B),
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*
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* otherwise:
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*
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* vecs(A) =
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* round_down(V * ncpu(A) / N) =
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* round_down((N - delta) * ncpu(A) / N) =
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* round_down((N * ncpu(A) - delta * ncpu(A)) / N) >=
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* round_down((N * ncpu(A) - delta * N) / N) =
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* cpu(A) - delta
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*
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* then:
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*
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* vecs(A) - V >= ncpu(A) - delta - V
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* =>
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* V - vecs(A) <= V + delta - ncpu(A)
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* =>
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* vecs(B) <= N - ncpu(A)
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* =>
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* vecs(B) <= cpu(B)
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*
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* For nodes >= 3, it can be thought as one node and another big
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* node given that is exactly what this algorithm is implemented,
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* and we always re-calculate 'remaining_ncpus' & 'numvecs', and
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* finally for each node X: vecs(X) <= ncpu(X).
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*
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*/
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for (n = 0; n < nr_node_ids; n++) {
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unsigned nvectors, ncpus;
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if (node_vectors[n].ncpus == UINT_MAX)
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continue;
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WARN_ON_ONCE(numvecs == 0);
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ncpus = node_vectors[n].ncpus;
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nvectors = max_t(unsigned, 1,
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numvecs * ncpus / remaining_ncpus);
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WARN_ON_ONCE(nvectors > ncpus);
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node_vectors[n].nvectors = nvectors;
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remaining_ncpus -= ncpus;
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numvecs -= nvectors;
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}
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}
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static int __irq_build_affinity_masks(unsigned int startvec,
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unsigned int numvecs,
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unsigned int firstvec,
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cpumask_var_t *node_to_cpumask,
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const struct cpumask *cpu_mask,
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struct cpumask *nmsk,
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struct irq_affinity_desc *masks)
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{
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unsigned int i, n, nodes, cpus_per_vec, extra_vecs, done = 0;
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unsigned int last_affv = firstvec + numvecs;
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unsigned int curvec = startvec;
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nodemask_t nodemsk = NODE_MASK_NONE;
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struct node_vectors *node_vectors;
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if (!cpumask_weight(cpu_mask))
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return 0;
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nodes = get_nodes_in_cpumask(node_to_cpumask, cpu_mask, &nodemsk);
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/*
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* If the number of nodes in the mask is greater than or equal the
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* number of vectors we just spread the vectors across the nodes.
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*/
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if (numvecs <= nodes) {
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for_each_node_mask(n, nodemsk) {
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/* Ensure that only CPUs which are in both masks are set */
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cpumask_and(nmsk, cpu_mask, node_to_cpumask[n]);
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cpumask_or(&masks[curvec].mask, &masks[curvec].mask, nmsk);
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if (++curvec == last_affv)
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curvec = firstvec;
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}
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return numvecs;
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}
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node_vectors = kcalloc(nr_node_ids,
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sizeof(struct node_vectors),
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GFP_KERNEL);
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if (!node_vectors)
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return -ENOMEM;
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/* allocate vector number for each node */
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alloc_nodes_vectors(numvecs, node_to_cpumask, cpu_mask,
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nodemsk, nmsk, node_vectors);
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for (i = 0; i < nr_node_ids; i++) {
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unsigned int ncpus, v;
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struct node_vectors *nv = &node_vectors[i];
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if (nv->nvectors == UINT_MAX)
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continue;
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/* Get the cpus on this node which are in the mask */
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cpumask_and(nmsk, cpu_mask, node_to_cpumask[nv->id]);
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ncpus = cpumask_weight(nmsk);
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if (!ncpus)
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continue;
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WARN_ON_ONCE(nv->nvectors > ncpus);
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/* Account for rounding errors */
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extra_vecs = ncpus - nv->nvectors * (ncpus / nv->nvectors);
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/* Spread allocated vectors on CPUs of the current node */
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for (v = 0; v < nv->nvectors; v++, curvec++) {
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cpus_per_vec = ncpus / nv->nvectors;
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/* Account for extra vectors to compensate rounding errors */
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if (extra_vecs) {
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cpus_per_vec++;
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--extra_vecs;
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}
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/*
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* wrapping has to be considered given 'startvec'
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* may start anywhere
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*/
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if (curvec >= last_affv)
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curvec = firstvec;
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irq_spread_init_one(&masks[curvec].mask, nmsk,
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cpus_per_vec);
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}
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done += nv->nvectors;
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}
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kfree(node_vectors);
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return done;
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}
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/*
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* build affinity in two stages:
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* 1) spread present CPU on these vectors
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* 2) spread other possible CPUs on these vectors
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*/
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static int irq_build_affinity_masks(unsigned int startvec, unsigned int numvecs,
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unsigned int firstvec,
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struct irq_affinity_desc *masks)
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{
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unsigned int curvec = startvec, nr_present = 0, nr_others = 0;
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cpumask_var_t *node_to_cpumask;
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cpumask_var_t nmsk, npresmsk;
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int ret = -ENOMEM;
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if (!zalloc_cpumask_var(&nmsk, GFP_KERNEL))
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return ret;
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if (!zalloc_cpumask_var(&npresmsk, GFP_KERNEL))
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goto fail_nmsk;
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node_to_cpumask = alloc_node_to_cpumask();
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if (!node_to_cpumask)
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goto fail_npresmsk;
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/* Stabilize the cpumasks */
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get_online_cpus();
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build_node_to_cpumask(node_to_cpumask);
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/* Spread on present CPUs starting from affd->pre_vectors */
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ret = __irq_build_affinity_masks(curvec, numvecs, firstvec,
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node_to_cpumask, cpu_present_mask,
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nmsk, masks);
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if (ret < 0)
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goto fail_build_affinity;
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nr_present = ret;
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/*
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* Spread on non present CPUs starting from the next vector to be
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* handled. If the spreading of present CPUs already exhausted the
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* vector space, assign the non present CPUs to the already spread
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* out vectors.
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*/
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if (nr_present >= numvecs)
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curvec = firstvec;
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else
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curvec = firstvec + nr_present;
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cpumask_andnot(npresmsk, cpu_possible_mask, cpu_present_mask);
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ret = __irq_build_affinity_masks(curvec, numvecs, firstvec,
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node_to_cpumask, npresmsk, nmsk,
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masks);
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if (ret >= 0)
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nr_others = ret;
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fail_build_affinity:
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put_online_cpus();
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if (ret >= 0)
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WARN_ON(nr_present + nr_others < numvecs);
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free_node_to_cpumask(node_to_cpumask);
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fail_npresmsk:
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free_cpumask_var(npresmsk);
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fail_nmsk:
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free_cpumask_var(nmsk);
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return ret < 0 ? ret : 0;
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}
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static void default_calc_sets(struct irq_affinity *affd, unsigned int affvecs)
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{
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affd->nr_sets = 1;
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affd->set_size[0] = affvecs;
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}
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/**
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* irq_create_affinity_masks - Create affinity masks for multiqueue spreading
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* @nvecs: The total number of vectors
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* @affd: Description of the affinity requirements
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*
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* Returns the irq_affinity_desc pointer or NULL if allocation failed.
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*/
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struct irq_affinity_desc *
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irq_create_affinity_masks(unsigned int nvecs, struct irq_affinity *affd)
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{
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unsigned int affvecs, curvec, usedvecs, i;
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struct irq_affinity_desc *masks = NULL;
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/*
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* Determine the number of vectors which need interrupt affinities
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* assigned. If the pre/post request exhausts the available vectors
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* then nothing to do here except for invoking the calc_sets()
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* callback so the device driver can adjust to the situation.
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*/
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if (nvecs > affd->pre_vectors + affd->post_vectors)
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affvecs = nvecs - affd->pre_vectors - affd->post_vectors;
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else
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affvecs = 0;
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/*
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* Simple invocations do not provide a calc_sets() callback. Install
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* the generic one.
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*/
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if (!affd->calc_sets)
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affd->calc_sets = default_calc_sets;
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/* Recalculate the sets */
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affd->calc_sets(affd, affvecs);
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if (WARN_ON_ONCE(affd->nr_sets > IRQ_AFFINITY_MAX_SETS))
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return NULL;
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/* Nothing to assign? */
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if (!affvecs)
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return NULL;
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masks = kcalloc(nvecs, sizeof(*masks), GFP_KERNEL);
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if (!masks)
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return NULL;
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/* Fill out vectors at the beginning that don't need affinity */
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for (curvec = 0; curvec < affd->pre_vectors; curvec++)
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cpumask_copy(&masks[curvec].mask, irq_default_affinity);
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/*
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* Spread on present CPUs starting from affd->pre_vectors. If we
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* have multiple sets, build each sets affinity mask separately.
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*/
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for (i = 0, usedvecs = 0; i < affd->nr_sets; i++) {
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unsigned int this_vecs = affd->set_size[i];
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int ret;
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ret = irq_build_affinity_masks(curvec, this_vecs,
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curvec, masks);
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if (ret) {
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kfree(masks);
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return NULL;
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}
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curvec += this_vecs;
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usedvecs += this_vecs;
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}
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/* Fill out vectors at the end that don't need affinity */
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if (usedvecs >= affvecs)
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curvec = affd->pre_vectors + affvecs;
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else
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curvec = affd->pre_vectors + usedvecs;
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for (; curvec < nvecs; curvec++)
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cpumask_copy(&masks[curvec].mask, irq_default_affinity);
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/* Mark the managed interrupts */
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for (i = affd->pre_vectors; i < nvecs - affd->post_vectors; i++)
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masks[i].is_managed = 1;
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return masks;
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}
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/**
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* irq_calc_affinity_vectors - Calculate the optimal number of vectors
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* @minvec: The minimum number of vectors available
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* @maxvec: The maximum number of vectors available
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* @affd: Description of the affinity requirements
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*/
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unsigned int irq_calc_affinity_vectors(unsigned int minvec, unsigned int maxvec,
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const struct irq_affinity *affd)
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{
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unsigned int resv = affd->pre_vectors + affd->post_vectors;
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unsigned int set_vecs;
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if (resv > minvec)
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return 0;
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if (affd->calc_sets) {
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set_vecs = maxvec - resv;
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} else {
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get_online_cpus();
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set_vecs = cpumask_weight(cpu_possible_mask);
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put_online_cpus();
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}
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return resv + min(set_vecs, maxvec - resv);
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}
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