6.1-stable review patch. If anyone has any objections, please let me know.
------------------
From: Ming Lei ming.lei@redhat.com
[ Upstream commit f7b3ea8cf72f3d6060fe08e461805181e7450a13 ]
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 Stable-dep-of: 0263f92fadbb ("lib/group_cpus.c: avoid acquiring cpu hotplug lock in group_cpus_evenly") Signed-off-by: Sasha Levin sashal@kernel.org --- MAINTAINERS | 2 + include/linux/group_cpus.h | 14 ++ kernel/irq/affinity.c | 398 +--------------------------------- lib/Makefile | 2 + lib/group_cpus.c | 427 +++++++++++++++++++++++++++++++++++++ 5 files changed, 446 insertions(+), 397 deletions(-) create mode 100644 include/linux/group_cpus.h create mode 100644 lib/group_cpus.c
diff --git a/MAINTAINERS b/MAINTAINERS index 07a9c274c0e29..13d1078808bb5 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -10803,6 +10803,8 @@ L: linux-kernel@vger.kernel.org S: Maintained T: git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git irq/core F: kernel/irq/ +F: include/linux/group_cpus.h +F: lib/group_cpus.c
IRQCHIP DRIVERS M: Thomas Gleixner tglx@linutronix.de diff --git a/include/linux/group_cpus.h b/include/linux/group_cpus.h new file mode 100644 index 0000000000000..e42807ec61f6e --- /dev/null +++ b/include/linux/group_cpus.h @@ -0,0 +1,14 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (C) 2016 Thomas Gleixner. + * Copyright (C) 2016-2017 Christoph Hellwig. + */ + +#ifndef __LINUX_GROUP_CPUS_H +#define __LINUX_GROUP_CPUS_H +#include <linux/kernel.h> +#include <linux/cpu.h> + +struct cpumask *group_cpus_evenly(unsigned int numgrps); + +#endif diff --git a/kernel/irq/affinity.c b/kernel/irq/affinity.c index 54083331f1bcb..44a4eba80315c 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) { diff --git a/lib/Makefile b/lib/Makefile index 5ffe72ec99797..6f1611d053e6a 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -361,6 +361,8 @@ obj-$(CONFIG_SBITMAP) += sbitmap.o
obj-$(CONFIG_PARMAN) += parman.o
+obj-y += group_cpus.o + # GCC library routines obj-$(CONFIG_GENERIC_LIB_ASHLDI3) += ashldi3.o obj-$(CONFIG_GENERIC_LIB_ASHRDI3) += ashrdi3.o diff --git a/lib/group_cpus.c b/lib/group_cpus.c new file mode 100644 index 0000000000000..99f08c6cb9d97 --- /dev/null +++ b/lib/group_cpus.c @@ -0,0 +1,427 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2016 Thomas Gleixner. + * Copyright (C) 2016-2017 Christoph Hellwig. + */ +#include <linux/kernel.h> +#include <linux/slab.h> +#include <linux/cpu.h> +#include <linux/sort.h> +#include <linux/group_cpus.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; +} + +#ifdef CONFIG_SMP +/** + * group_cpus_evenly - Group all CPUs evenly per NUMA/CPU locality + * @numgrps: number of groups + * + * Return: cpumask array if successful, NULL otherwise. And each element + * includes CPUs assigned to this group + * + * Try to put close CPUs from viewpoint of CPU and NUMA locality into + * same group, and run two-stage grouping: + * 1) allocate present CPUs on these groups evenly first + * 2) allocate other possible CPUs on these groups evenly + * + * We guarantee in the resulted grouping that all CPUs are covered, and + * no same CPU is assigned to multiple groups + */ +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; +} +#else +struct cpumask *group_cpus_evenly(unsigned int numgrps) +{ + struct cpumask *masks = kcalloc(numgrps, sizeof(*masks), GFP_KERNEL); + + if (!masks) + return NULL; + + /* assign all CPUs(cpu 0) to the 1st group only */ + cpumask_copy(&masks[0], cpu_possible_mask); + return masks; +} +#endif