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/*
* Copyright (C) 2016 Thomas Gleixner.
* Copyright (C) 2016-2017 Christoph Hellwig.
*/
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/cpu.h>
static void irq_spread_init_one(struct cpumask *irqmsk, struct cpumask *nmsk,
int cpus_per_vec)
{
const struct cpumask *siblmsk;
int cpu, sibl;
for ( ; cpus_per_vec > 0; ) {
cpu = cpumask_first(nmsk);
/* Should not happen, but I'm too lazy to think about it */
if (cpu >= nr_cpu_ids)
return;
cpumask_clear_cpu(cpu, nmsk);
cpumask_set_cpu(cpu, irqmsk);
cpus_per_vec--;
/* If the cpu has siblings, use them first */
siblmsk = topology_sibling_cpumask(cpu);
for (sibl = -1; cpus_per_vec > 0; ) {
sibl = cpumask_next(sibl, siblmsk);
if (sibl >= nr_cpu_ids)
break;
if (!cpumask_test_and_clear_cpu(sibl, nmsk))
continue;
cpumask_set_cpu(sibl, irqmsk);
cpus_per_vec--;
}
}
}
static cpumask_var_t *alloc_node_to_present_cpumask(void)
{
cpumask_var_t *masks;
int node;
masks = kcalloc(nr_node_ids, sizeof(cpumask_var_t), GFP_KERNEL);
if (!masks)
return NULL;
for (node = 0; node < nr_node_ids; node++) {
if (!zalloc_cpumask_var(&masks[node], GFP_KERNEL))
goto out_unwind;
}
return masks;
out_unwind:
while (--node >= 0)
free_cpumask_var(masks[node]);
kfree(masks);
return NULL;
}
static void free_node_to_present_cpumask(cpumask_var_t *masks)
{
int node;
for (node = 0; node < nr_node_ids; node++)
free_cpumask_var(masks[node]);
kfree(masks);
}
static void build_node_to_present_cpumask(cpumask_var_t *masks)
{
int cpu;
for_each_present_cpu(cpu)
cpumask_set_cpu(cpu, masks[cpu_to_node(cpu)]);
}
static int get_nodes_in_cpumask(cpumask_var_t *node_to_present_cpumask,
const struct cpumask *mask, nodemask_t *nodemsk)
{
int n, nodes = 0;
/* Calculate the number of nodes in the supplied affinity mask */
for_each_node(n) {
if (cpumask_intersects(mask, node_to_present_cpumask[n])) {
node_set(n, *nodemsk);
nodes++;
}
}
return nodes;
}
/**
* irq_create_affinity_masks - Create affinity masks for multiqueue spreading
* @nvecs: The total number of vectors
* @affd: Description of the affinity requirements
*
* Returns the masks pointer or NULL if allocation failed.
*/
struct cpumask *
irq_create_affinity_masks(int nvecs, const struct irq_affinity *affd)
{
int n, nodes, cpus_per_vec, extra_vecs, curvec;
int affv = nvecs - affd->pre_vectors - affd->post_vectors;
int last_affv = affv + affd->pre_vectors;
nodemask_t nodemsk = NODE_MASK_NONE;
struct cpumask *masks;
cpumask_var_t nmsk, *node_to_present_cpumask;
if (!zalloc_cpumask_var(&nmsk, GFP_KERNEL))
return NULL;
masks = kcalloc(nvecs, sizeof(*masks), GFP_KERNEL);
if (!masks)
goto out;
node_to_present_cpumask = alloc_node_to_present_cpumask();
if (!node_to_present_cpumask)
goto out;
/* Fill out vectors at the beginning that don't need affinity */
for (curvec = 0; curvec < affd->pre_vectors; curvec++)
cpumask_copy(masks + curvec, irq_default_affinity);
/* Stabilize the cpumasks */
get_online_cpus();
build_node_to_present_cpumask(node_to_present_cpumask);
nodes = get_nodes_in_cpumask(node_to_present_cpumask, cpu_present_mask,
&nodemsk);
/*
* If the number of nodes in the mask is greater than or equal the
* number of vectors we just spread the vectors across the nodes.
*/
if (affv <= nodes) {
for_each_node_mask(n, nodemsk) {
cpumask_copy(masks + curvec,
node_to_present_cpumask[n]);
if (++curvec == last_affv)
break;
}
goto done;
}
for_each_node_mask(n, nodemsk) {
int ncpus, v, vecs_to_assign, vecs_per_node;
/* Spread the vectors per node */
vecs_per_node = (affv - (curvec - affd->pre_vectors)) / nodes;
/* Get the cpus on this node which are in the mask */
cpumask_and(nmsk, cpu_present_mask, node_to_present_cpumask[n]);
/* Calculate the number of cpus per vector */
ncpus = cpumask_weight(nmsk);
vecs_to_assign = min(vecs_per_node, ncpus);
/* Account for rounding errors */
extra_vecs = ncpus - vecs_to_assign * (ncpus / vecs_to_assign);
for (v = 0; curvec < last_affv && v < vecs_to_assign;
curvec++, v++) {
cpus_per_vec = ncpus / vecs_to_assign;
/* Account for extra vectors to compensate rounding errors */
if (extra_vecs) {
cpus_per_vec++;
--extra_vecs;
}
irq_spread_init_one(masks + curvec, nmsk, cpus_per_vec);
}
if (curvec >= last_affv)
break;
--nodes;
}
done:
put_online_cpus();
/* Fill out vectors at the end that don't need affinity */
for (; curvec < nvecs; curvec++)
cpumask_copy(masks + curvec, irq_default_affinity);
free_node_to_present_cpumask(node_to_present_cpumask);
out:
free_cpumask_var(nmsk);
return masks;
}
/**
* irq_calc_affinity_vectors - Calculate the optimal number of vectors
* @maxvec: The maximum number of vectors available
* @affd: Description of the affinity requirements
*/
int irq_calc_affinity_vectors(int maxvec, const struct irq_affinity *affd)
{
int resv = affd->pre_vectors + affd->post_vectors;
int vecs = maxvec - resv;
int ret;
get_online_cpus();
ret = min_t(int, cpumask_weight(cpu_present_mask), vecs) + resv;
put_online_cpus();
return ret;
}
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