kernel/irq/affinity.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * 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_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_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_cpumask(cpumask_var_t *masks)
 {
 	int cpu;

 	for_each_possible_cpu(cpu)
 		cpumask_set_cpu(cpu, masks[cpu_to_node(cpu)]);
 }

 static int get_nodes_in_cpumask(cpumask_var_t *node_to_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_cpumask[n])) {
 			node_set(n, *nodemsk);
 			nodes++;
 		}
 	}
 	return nodes;
 }

 static int irq_build_affinity_masks(const struct irq_affinity *affd,
 				    int startvec, int numvecs,
 				    cpumask_var_t *node_to_cpumask,
 				    const struct cpumask *cpu_mask,
 				    struct cpumask *nmsk,
 				    struct cpumask *masks)
 {
 	int n, nodes, cpus_per_vec, extra_vecs, done = 0;
 	int last_affv = affd->pre_vectors + numvecs;
 	int curvec = startvec;
 	nodemask_t nodemsk = NODE_MASK_NONE;

 	if (!cpumask_weight(cpu_mask))
 		return 0;

 	nodes = get_nodes_in_cpumask(node_to_cpumask, cpu_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 (numvecs <= nodes) {
 		for_each_node_mask(n, nodemsk) {
 			cpumask_copy(masks + curvec, node_to_cpumask[n]);
 			if (++done == numvecs)
 				break;
 			if (++curvec == last_affv)
 				curvec = affd->pre_vectors;
 		}
 		goto out;
 	}

 	for_each_node_mask(n, nodemsk) {
 		int ncpus, v, vecs_to_assign, vecs_per_node;

 		/* Spread the vectors per node */
 		vecs_per_node = (numvecs - (curvec - affd->pre_vectors)) / nodes;

 		/* Get the cpus on this node which are in the mask */
 		cpumask_and(nmsk, cpu_mask, node_to_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);
 		}

 		done += v;
 		if (done >= numvecs)
 			break;
 		if (curvec >= last_affv)
 			curvec = affd->pre_vectors;
 		--nodes;
 	}

 out:
 	return done;
 }

 /**
  * 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 affvecs = nvecs - affd->pre_vectors - affd->post_vectors;
 	int curvec, usedvecs;
 	cpumask_var_t nmsk, npresmsk, *node_to_cpumask;
 	struct cpumask *masks = NULL;

 	/*
 	 * If there aren't any vectors left after applying the pre/post
 	 * vectors don't bother with assigning affinity.
 	 */
 	if (nvecs == affd->pre_vectors + affd->post_vectors)
 		return NULL;

 	if (!zalloc_cpumask_var(&nmsk, GFP_KERNEL))
 		return NULL;

 	if (!zalloc_cpumask_var(&npresmsk, GFP_KERNEL))
 		goto outcpumsk;

 	node_to_cpumask = alloc_node_to_cpumask();
 	if (!node_to_cpumask)
 		goto outnpresmsk;

 	masks = kcalloc(nvecs, sizeof(*masks), GFP_KERNEL);
 	if (!masks)
 		goto outnodemsk;

 	/* 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_cpumask(node_to_cpumask);

 	/* Spread on present CPUs starting from affd->pre_vectors */
 	usedvecs = irq_build_affinity_masks(affd, curvec, affvecs,
 					    node_to_cpumask, cpu_present_mask,
 					    nmsk, masks);

 	/*
 	 * Spread on non present CPUs starting from the next vector to be
 	 * handled. If the spreading of present CPUs already exhausted the
 	 * vector space, assign the non present CPUs to the already spread
 	 * out vectors.
 	 */
 	if (usedvecs >= affvecs)
 		curvec = affd->pre_vectors;
 	else
 		curvec = affd->pre_vectors + usedvecs;
 	cpumask_andnot(npresmsk, cpu_possible_mask, cpu_present_mask);
 	usedvecs += irq_build_affinity_masks(affd, curvec, affvecs,
 					     node_to_cpumask, npresmsk,
 					     nmsk, masks);
 	put_online_cpus();

 	/* Fill out vectors at the end that don't need affinity */
 	if (usedvecs >= affvecs)
 		curvec = affd->pre_vectors + affvecs;
 	else
 		curvec = affd->pre_vectors + usedvecs;
 	for (; curvec < nvecs; curvec++)
 		cpumask_copy(masks + curvec, irq_default_affinity);

 outnodemsk:
 	free_node_to_cpumask(node_to_cpumask);
 outnpresmsk:
 	free_cpumask_var(npresmsk);
 outcpumsk:
 	free_cpumask_var(nmsk);
 	return masks;
 }

 /**
  * irq_calc_affinity_vectors - Calculate the optimal number of vectors
  * @minvec:	The minimum number of vectors available
  * @maxvec:	The maximum number of vectors available
  * @affd:	Description of the affinity requirements
  */
 int irq_calc_affinity_vectors(int minvec, int maxvec, const struct irq_affinity *affd)
 {
 	int resv = affd->pre_vectors + affd->post_vectors;
 	int vecs = maxvec - resv;
 	int ret;

 	if (resv > minvec)
 		return 0;

 	get_online_cpus();
 	ret = min_t(int, cpumask_weight(cpu_possible_mask), vecs) + resv;
 	put_online_cpus();
 	return ret;
 }
	// SPDX-License-Identifier: GPL-2.0
	/*
	* 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_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_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_cpumask(cpumask_var_t *masks)
	{
	int cpu;

	for_each_possible_cpu(cpu)
	cpumask_set_cpu(cpu, masks[cpu_to_node(cpu)]);
	}

	static int get_nodes_in_cpumask(cpumask_var_t *node_to_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_cpumask[n])) {
	node_set(n, *nodemsk);
	nodes++;
	}
	}
	return nodes;
	}

	static int irq_build_affinity_masks(const struct irq_affinity *affd,
	int startvec, int numvecs,
	cpumask_var_t *node_to_cpumask,
	const struct cpumask *cpu_mask,
	struct cpumask *nmsk,
	struct cpumask *masks)
	{
	int n, nodes, cpus_per_vec, extra_vecs, done = 0;
	int last_affv = affd->pre_vectors + numvecs;
	int curvec = startvec;
	nodemask_t nodemsk = NODE_MASK_NONE;

	if (!cpumask_weight(cpu_mask))
	return 0;

	nodes = get_nodes_in_cpumask(node_to_cpumask, cpu_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 (numvecs <= nodes) {
	for_each_node_mask(n, nodemsk) {
	cpumask_copy(masks + curvec, node_to_cpumask[n]);
	if (++done == numvecs)
	break;
	if (++curvec == last_affv)
	curvec = affd->pre_vectors;
	}
	goto out;
	}

	for_each_node_mask(n, nodemsk) {
	int ncpus, v, vecs_to_assign, vecs_per_node;

	/* Spread the vectors per node */
	vecs_per_node = (numvecs - (curvec - affd->pre_vectors)) / nodes;

	/* Get the cpus on this node which are in the mask */
	cpumask_and(nmsk, cpu_mask, node_to_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);
	}

	done += v;
	if (done >= numvecs)
	break;
	if (curvec >= last_affv)
	curvec = affd->pre_vectors;
	--nodes;
	}

	out:
	return done;
	}

	/**
	* 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 affvecs = nvecs - affd->pre_vectors - affd->post_vectors;
	int curvec, usedvecs;
	cpumask_var_t nmsk, npresmsk, *node_to_cpumask;
	struct cpumask *masks = NULL;

	/*
	* If there aren't any vectors left after applying the pre/post
	* vectors don't bother with assigning affinity.
	*/
	if (nvecs == affd->pre_vectors + affd->post_vectors)
	return NULL;

	if (!zalloc_cpumask_var(&nmsk, GFP_KERNEL))
	return NULL;

	if (!zalloc_cpumask_var(&npresmsk, GFP_KERNEL))
	goto outcpumsk;

	node_to_cpumask = alloc_node_to_cpumask();
	if (!node_to_cpumask)
	goto outnpresmsk;

	masks = kcalloc(nvecs, sizeof(*masks), GFP_KERNEL);
	if (!masks)
	goto outnodemsk;

	/* 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_cpumask(node_to_cpumask);

	/* Spread on present CPUs starting from affd->pre_vectors */
	usedvecs = irq_build_affinity_masks(affd, curvec, affvecs,
	node_to_cpumask, cpu_present_mask,
	nmsk, masks);

	/*
	* Spread on non present CPUs starting from the next vector to be
	* handled. If the spreading of present CPUs already exhausted the
	* vector space, assign the non present CPUs to the already spread
	* out vectors.
	*/
	if (usedvecs >= affvecs)
	curvec = affd->pre_vectors;
	else
	curvec = affd->pre_vectors + usedvecs;
	cpumask_andnot(npresmsk, cpu_possible_mask, cpu_present_mask);
	usedvecs += irq_build_affinity_masks(affd, curvec, affvecs,
	node_to_cpumask, npresmsk,
	nmsk, masks);
	put_online_cpus();

	/* Fill out vectors at the end that don't need affinity */
	if (usedvecs >= affvecs)
	curvec = affd->pre_vectors + affvecs;
	else
	curvec = affd->pre_vectors + usedvecs;
	for (; curvec < nvecs; curvec++)
	cpumask_copy(masks + curvec, irq_default_affinity);

	outnodemsk:
	free_node_to_cpumask(node_to_cpumask);
	outnpresmsk:
	free_cpumask_var(npresmsk);
	outcpumsk:
	free_cpumask_var(nmsk);
	return masks;
	}

	/**
	* irq_calc_affinity_vectors - Calculate the optimal number of vectors
	* @minvec: The minimum number of vectors available
	* @maxvec: The maximum number of vectors available
	* @affd: Description of the affinity requirements
	*/
	int irq_calc_affinity_vectors(int minvec, int maxvec, const struct irq_affinity *affd)
	{
	int resv = affd->pre_vectors + affd->post_vectors;
	int vecs = maxvec - resv;
	int ret;

	if (resv > minvec)
	return 0;

	get_online_cpus();
	ret = min_t(int, cpumask_weight(cpu_possible_mask), vecs) + resv;
	put_online_cpus();
	return ret;
	}