genirq/affinity: Move group_cpus_evenly() into lib/

group_cpus_evenly() has become a generic function which can be used for
other subsystems than the interrupt subsystem, so move it into lib/.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jens Axboe <axboe@kernel.dk>                                                                                                                                                                                                    
Link: https://lore.kernel.org/r/20221227022905.352674-6-ming.lei@redhat.com

1 files changed, 1 insertions, 397 deletions

diff --git a/kernel/irq/affinity.c b/kernel/irq/affinity.c
index 54083331f1bc..44a4eba80315 100644
--- a/kernel/irq/affinity.c
+++ b/kernel/irq/affinity.c
@@ -7,403 +7,7 @@
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/cpu.h>
-#include <linux/sort.h>
-
-static void grp_spread_init_one(struct cpumask *irqmsk, struct cpumask *nmsk,
-				unsigned int cpus_per_grp)
-{
-	const struct cpumask *siblmsk;
-	int cpu, sibl;
-
-	for ( ; cpus_per_grp > 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_grp--;
-
-		/* If the cpu has siblings, use them first */
-		siblmsk = topology_sibling_cpumask(cpu);
-		for (sibl = -1; cpus_per_grp > 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_grp--;
-		}
-	}
-}
-
-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;
-}
-
-struct node_groups {
-	unsigned id;
-
-	union {
-		unsigned ngroups;
-		unsigned ncpus;
-	};
-};
-
-static int ncpus_cmp_func(const void *l, const void *r)
-{
-	const struct node_groups *ln = l;
-	const struct node_groups *rn = r;
-
-	return ln->ncpus - rn->ncpus;
-}
-
-/*
- * Allocate group number for each node, so that for each node:
- *
- * 1) the allocated number is >= 1
- *
- * 2) the allocated number is <= active CPU number of this node
- *
- * The actual allocated total groups may be less than @numgrps when
- * active total CPU number is less than @numgrps.
- *
- * Active CPUs means the CPUs in '@cpu_mask AND @node_to_cpumask[]'
- * for each node.
- */
-static void alloc_nodes_groups(unsigned int numgrps,
-			       cpumask_var_t *node_to_cpumask,
-			       const struct cpumask *cpu_mask,
-			       const nodemask_t nodemsk,
-			       struct cpumask *nmsk,
-			       struct node_groups *node_groups)
-{
-	unsigned n, remaining_ncpus = 0;
-
-	for (n = 0; n < nr_node_ids; n++) {
-		node_groups[n].id = n;
-		node_groups[n].ncpus = UINT_MAX;
-	}
-
-	for_each_node_mask(n, nodemsk) {
-		unsigned ncpus;
-
-		cpumask_and(nmsk, cpu_mask, node_to_cpumask[n]);
-		ncpus = cpumask_weight(nmsk);
-
-		if (!ncpus)
-			continue;
-		remaining_ncpus += ncpus;
-		node_groups[n].ncpus = ncpus;
-	}
-
-	numgrps = min_t(unsigned, remaining_ncpus, numgrps);
-
-	sort(node_groups, nr_node_ids, sizeof(node_groups[0]),
-	     ncpus_cmp_func, NULL);
-
-	/*
-	 * Allocate groups for each node according to the ratio of this
-	 * node's nr_cpus to remaining un-assigned ncpus. 'numgrps' is
-	 * bigger than number of active numa nodes. Always start the
-	 * allocation from the node with minimized nr_cpus.
-	 *
-	 * This way guarantees that each active node gets allocated at
-	 * least one group, and the theory is simple: over-allocation
-	 * is only done when this node is assigned by one group, so
-	 * other nodes will be allocated >= 1 groups, since 'numgrps' is
-	 * bigger than number of numa nodes.
-	 *
-	 * One perfect invariant is that number of allocated groups for
-	 * each node is <= CPU count of this node:
-	 *
-	 * 1) suppose there are two nodes: A and B
-	 * 	ncpu(X) is CPU count of node X
-	 * 	grps(X) is the group count allocated to node X via this
-	 * 	algorithm
-	 *
-	 * 	ncpu(A) <= ncpu(B)
-	 * 	ncpu(A) + ncpu(B) = N
-	 * 	grps(A) + grps(B) = G
-	 *
-	 * 	grps(A) = max(1, round_down(G * ncpu(A) / N))
-	 * 	grps(B) = G - grps(A)
-	 *
-	 * 	both N and G are integer, and 2 <= G <= N, suppose
-	 * 	G = N - delta, and 0 <= delta <= N - 2
-	 *
-	 * 2) obviously grps(A) <= ncpu(A) because:
-	 *
-	 * 	if grps(A) is 1, then grps(A) <= ncpu(A) given
-	 * 	ncpu(A) >= 1
-	 *
-	 * 	otherwise,
-	 * 		grps(A) <= G * ncpu(A) / N <= ncpu(A), given G <= N
-	 *
-	 * 3) prove how grps(B) <= ncpu(B):
-	 *
-	 * 	if round_down(G * ncpu(A) / N) == 0, vecs(B) won't be
-	 * 	over-allocated, so grps(B) <= ncpu(B),
-	 *
-	 * 	otherwise:
-	 *
-	 * 	grps(A) =
-	 * 		round_down(G * ncpu(A) / N) =
-	 * 		round_down((N - delta) * ncpu(A) / N) =
-	 * 		round_down((N * ncpu(A) - delta * ncpu(A)) / N)	 >=
-	 * 		round_down((N * ncpu(A) - delta * N) / N)	 =
-	 * 		cpu(A) - delta
-	 *
-	 * 	then:
-	 *
-	 * 	grps(A) - G >= ncpu(A) - delta - G
-	 * 	=>
-	 * 	G - grps(A) <= G + delta - ncpu(A)
-	 * 	=>
-	 * 	grps(B) <= N - ncpu(A)
-	 * 	=>
-	 * 	grps(B) <= cpu(B)
-	 *
-	 * For nodes >= 3, it can be thought as one node and another big
-	 * node given that is exactly what this algorithm is implemented,
-	 * and we always re-calculate 'remaining_ncpus' & 'numgrps', and
-	 * finally for each node X: grps(X) <= ncpu(X).
-	 *
-	 */
-	for (n = 0; n < nr_node_ids; n++) {
-		unsigned ngroups, ncpus;
-
-		if (node_groups[n].ncpus == UINT_MAX)
-			continue;
-
-		WARN_ON_ONCE(numgrps == 0);
-
-		ncpus = node_groups[n].ncpus;
-		ngroups = max_t(unsigned, 1,
-				 numgrps * ncpus / remaining_ncpus);
-		WARN_ON_ONCE(ngroups > ncpus);
-
-		node_groups[n].ngroups = ngroups;
-
-		remaining_ncpus -= ncpus;
-		numgrps -= ngroups;
-	}
-}
-
-static int __group_cpus_evenly(unsigned int startgrp, unsigned int numgrps,
-			       cpumask_var_t *node_to_cpumask,
-			       const struct cpumask *cpu_mask,
-			       struct cpumask *nmsk, struct cpumask *masks)
-{
-	unsigned int i, n, nodes, cpus_per_grp, extra_grps, done = 0;
-	unsigned int last_grp = numgrps;
-	unsigned int curgrp = startgrp;
-	nodemask_t nodemsk = NODE_MASK_NONE;
-	struct node_groups *node_groups;
-
-	if (cpumask_empty(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 groups we just spread the groups across the nodes.
-	 */
-	if (numgrps <= nodes) {
-		for_each_node_mask(n, nodemsk) {
-			/* Ensure that only CPUs which are in both masks are set */
-			cpumask_and(nmsk, cpu_mask, node_to_cpumask[n]);
-			cpumask_or(&masks[curgrp], &masks[curgrp], nmsk);
-			if (++curgrp == last_grp)
-				curgrp = 0;
-		}
-		return numgrps;
-	}
-
-	node_groups = kcalloc(nr_node_ids,
-			       sizeof(struct node_groups),
-			       GFP_KERNEL);
-	if (!node_groups)
-		return -ENOMEM;
-
-	/* allocate group number for each node */
-	alloc_nodes_groups(numgrps, node_to_cpumask, cpu_mask,
-			   nodemsk, nmsk, node_groups);
-	for (i = 0; i < nr_node_ids; i++) {
-		unsigned int ncpus, v;
-		struct node_groups *nv = &node_groups[i];
-
-		if (nv->ngroups == UINT_MAX)
-			continue;
-
-		/* Get the cpus on this node which are in the mask */
-		cpumask_and(nmsk, cpu_mask, node_to_cpumask[nv->id]);
-		ncpus = cpumask_weight(nmsk);
-		if (!ncpus)
-			continue;
-
-		WARN_ON_ONCE(nv->ngroups > ncpus);
-
-		/* Account for rounding errors */
-		extra_grps = ncpus - nv->ngroups * (ncpus / nv->ngroups);
-
-		/* Spread allocated groups on CPUs of the current node */
-		for (v = 0; v < nv->ngroups; v++, curgrp++) {
-			cpus_per_grp = ncpus / nv->ngroups;
-
-			/* Account for extra groups to compensate rounding errors */
-			if (extra_grps) {
-				cpus_per_grp++;
-				--extra_grps;
-			}
-
-			/*
-			 * wrapping has to be considered given 'startgrp'
-			 * may start anywhere
-			 */
-			if (curgrp >= last_grp)
-				curgrp = 0;
-			grp_spread_init_one(&masks[curgrp], nmsk,
-						cpus_per_grp);
-		}
-		done += nv->ngroups;
-	}
-	kfree(node_groups);
-	return done;
-}
-
-/*
- * build affinity in two stages for each group, and try to put close CPUs
- * in viewpoint of CPU and NUMA locality into same group, and we run
- * two-stage grouping:
- *
- *	1) allocate present CPUs on these groups evenly first
- *	2) allocate other possible CPUs on these groups evenly
- */
-static struct cpumask *group_cpus_evenly(unsigned int numgrps)
-{
-	unsigned int curgrp = 0, nr_present = 0, nr_others = 0;
-	cpumask_var_t *node_to_cpumask;
-	cpumask_var_t nmsk, npresmsk;
-	int ret = -ENOMEM;
-	struct cpumask *masks = NULL;
-
-	if (!zalloc_cpumask_var(&nmsk, GFP_KERNEL))
-		return NULL;
-
-	if (!zalloc_cpumask_var(&npresmsk, GFP_KERNEL))
-		goto fail_nmsk;
-
-	node_to_cpumask = alloc_node_to_cpumask();
-	if (!node_to_cpumask)
-		goto fail_npresmsk;
-
-	masks = kcalloc(numgrps, sizeof(*masks), GFP_KERNEL);
-	if (!masks)
-		goto fail_node_to_cpumask;
-
-	/* Stabilize the cpumasks */
-	cpus_read_lock();
-	build_node_to_cpumask(node_to_cpumask);
-
-	/* grouping present CPUs first */
-	ret = __group_cpus_evenly(curgrp, numgrps, node_to_cpumask,
-				  cpu_present_mask, nmsk, masks);
-	if (ret < 0)
-		goto fail_build_affinity;
-	nr_present = ret;
-
-	/*
-	 * Allocate non present CPUs starting from the next group to be
-	 * handled. If the grouping of present CPUs already exhausted the
-	 * group space, assign the non present CPUs to the already
-	 * allocated out groups.
-	 */
-	if (nr_present >= numgrps)
-		curgrp = 0;
-	else
-		curgrp = nr_present;
-	cpumask_andnot(npresmsk, cpu_possible_mask, cpu_present_mask);
-	ret = __group_cpus_evenly(curgrp, numgrps, node_to_cpumask,
-				  npresmsk, nmsk, masks);
-	if (ret >= 0)
-		nr_others = ret;
-
- fail_build_affinity:
-	cpus_read_unlock();
-
-	if (ret >= 0)
-		WARN_ON(nr_present + nr_others < numgrps);
-
- fail_node_to_cpumask:
-	free_node_to_cpumask(node_to_cpumask);
-
- fail_npresmsk:
-	free_cpumask_var(npresmsk);
-
- fail_nmsk:
-	free_cpumask_var(nmsk);
-	if (ret < 0) {
-		kfree(masks);
-		return NULL;
-	}
-	return masks;
-}
+#include <linux/group_cpus.h>
 
 static void default_calc_sets(struct irq_affinity *affd, unsigned int affvecs)
 {