1
  2#include <linux/interrupt.h>
  3#include <linux/kernel.h>
  4#include <linux/slab.h>
  5#include <linux/cpu.h>
  6
  7static void irq_spread_init_one(struct cpumask *irqmsk, struct cpumask *nmsk,
  8				int cpus_per_vec)
  9{
 10	const struct cpumask *siblmsk;
 11	int cpu, sibl;
 12
 13	for ( ; cpus_per_vec > 0; ) {
 14		cpu = cpumask_first(nmsk);
 15
 16		/* Should not happen, but I'm too lazy to think about it */
 17		if (cpu >= nr_cpu_ids)
 18			return;
 19
 20		cpumask_clear_cpu(cpu, nmsk);
 21		cpumask_set_cpu(cpu, irqmsk);
 22		cpus_per_vec--;
 23
 24		/* If the cpu has siblings, use them first */
 25		siblmsk = topology_sibling_cpumask(cpu);
 26		for (sibl = -1; cpus_per_vec > 0; ) {
 27			sibl = cpumask_next(sibl, siblmsk);
 28			if (sibl >= nr_cpu_ids)
 29				break;
 30			if (!cpumask_test_and_clear_cpu(sibl, nmsk))
 31				continue;
 32			cpumask_set_cpu(sibl, irqmsk);
 33			cpus_per_vec--;
 34		}
 35	}
 36}
 37
 38static int get_nodes_in_cpumask(const struct cpumask *mask, nodemask_t *nodemsk)
 39{
 40	int n, nodes = 0;
 41
 42	/* Calculate the number of nodes in the supplied affinity mask */
 43	for_each_online_node(n) {
 44		if (cpumask_intersects(mask, cpumask_of_node(n))) {
 45			node_set(n, *nodemsk);
 46			nodes++;
 47		}
 48	}
 49	return nodes;
 50}
 51
 52/**
 53 * irq_create_affinity_masks - Create affinity masks for multiqueue spreading
 54 * @nvecs:	The total number of vectors
 55 * @affd:	Description of the affinity requirements
 56 *
 57 * Returns the masks pointer or NULL if allocation failed.
 58 */
 59struct cpumask *
 60irq_create_affinity_masks(int nvecs, const struct irq_affinity *affd)
 61{
 62	int n, nodes, vecs_per_node, cpus_per_vec, extra_vecs, curvec;
 63	int affv = nvecs - affd->pre_vectors - affd->post_vectors;
 64	int last_affv = affv + affd->pre_vectors;
 65	nodemask_t nodemsk = NODE_MASK_NONE;
 66	struct cpumask *masks;
 67	cpumask_var_t nmsk;
 68
 69	if (!zalloc_cpumask_var(&nmsk, GFP_KERNEL))
 70		return NULL;
 71
 72	masks = kcalloc(nvecs, sizeof(*masks), GFP_KERNEL);
 73	if (!masks)
 74		goto out;
 75
 76	/* Fill out vectors at the beginning that don't need affinity */
 77	for (curvec = 0; curvec < affd->pre_vectors; curvec++)
 78		cpumask_copy(masks + curvec, irq_default_affinity);
 79
 80	/* Stabilize the cpumasks */
 81	get_online_cpus();
 82	nodes = get_nodes_in_cpumask(cpu_online_mask, &nodemsk);
 83
 84	/*
 85	 * If the number of nodes in the mask is greater than or equal the
 86	 * number of vectors we just spread the vectors across the nodes.
 87	 */
 88	if (affv <= nodes) {
 89		for_each_node_mask(n, nodemsk) {
 90			cpumask_copy(masks + curvec, cpumask_of_node(n));
 91			if (++curvec == last_affv)
 92				break;
 93		}
 94		goto done;
 95	}
 96
 97	/* Spread the vectors per node */
 98	vecs_per_node = affv / nodes;
 99	/* Account for rounding errors */
100	extra_vecs = affv - (nodes * vecs_per_node);
101
102	for_each_node_mask(n, nodemsk) {
103		int ncpus, v, vecs_to_assign = vecs_per_node;
104
105		/* Get the cpus on this node which are in the mask */
106		cpumask_and(nmsk, cpu_online_mask, cpumask_of_node(n));
107
108		/* Calculate the number of cpus per vector */
109		ncpus = cpumask_weight(nmsk);
110
111		for (v = 0; curvec < last_affv && v < vecs_to_assign;
112		     curvec++, v++) {
113			cpus_per_vec = ncpus / vecs_to_assign;
114
115			/* Account for extra vectors to compensate rounding errors */
116			if (extra_vecs) {
117				cpus_per_vec++;
118				if (!--extra_vecs)
119					vecs_per_node++;
120			}
121			irq_spread_init_one(masks + curvec, nmsk, cpus_per_vec);
122		}
123
124		if (curvec >= last_affv)
125			break;
126	}
127
128done:
129	put_online_cpus();
130
131	/* Fill out vectors at the end that don't need affinity */
132	for (; curvec < nvecs; curvec++)
133		cpumask_copy(masks + curvec, irq_default_affinity);
134out:
135	free_cpumask_var(nmsk);
136	return masks;
137}
138
139/**
140 * irq_calc_affinity_vectors - Calculate the optimal number of vectors
141 * @maxvec:	The maximum number of vectors available
142 * @affd:	Description of the affinity requirements
143 */
144int irq_calc_affinity_vectors(int maxvec, const struct irq_affinity *affd)
145{
146	int resv = affd->pre_vectors + affd->post_vectors;
147	int vecs = maxvec - resv;
148	int cpus;
149
150	/* Stabilize the cpumasks */
151	get_online_cpus();
152	cpus = cpumask_weight(cpu_online_mask);
153	put_online_cpus();
154
155	return min(cpus, vecs) + resv;
156}