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514 lines
13 KiB
514 lines
13 KiB
// 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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cpumask_or(&masks[curvec].mask, &masks[curvec].mask, |
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node_to_cpumask[n]); |
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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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