diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Kconfig | 13 | ||||
| -rw-r--r-- | lib/Makefile | 2 | ||||
| -rw-r--r-- | lib/cpu_rmap.c | 269 |
3 files changed, 283 insertions, 1 deletions
diff --git a/lib/Kconfig b/lib/Kconfig index 0ee67e0..3a55a43 100644 --- a/lib/Kconfig +++ b/lib/Kconfig @@ -201,6 +201,10 @@ config DISABLE_OBSOLETE_CPUMASK_FUNCTIONS bool "Disable obsolete cpumask functions" if DEBUG_PER_CPU_MAPS depends on EXPERIMENTAL && BROKEN +config CPU_RMAP + bool + depends on SMP + # # Netlink attribute parsing support is select'ed if needed # @@ -217,6 +221,13 @@ config LRU_CACHE tristate config AVERAGE - bool + bool "Averaging functions" + help + This option is provided for the case where no in-kernel-tree + modules require averaging functions, but a module built outside + the kernel tree does. Such modules that use library averaging + functions require Y here. + + If unsure, say N. endmenu diff --git a/lib/Makefile b/lib/Makefile index cbb774f..b73ba01 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -110,6 +110,8 @@ obj-$(CONFIG_ATOMIC64_SELFTEST) += atomic64_test.o obj-$(CONFIG_AVERAGE) += average.o +obj-$(CONFIG_CPU_RMAP) += cpu_rmap.o + hostprogs-y := gen_crc32table clean-files := crc32table.h diff --git a/lib/cpu_rmap.c b/lib/cpu_rmap.c new file mode 100644 index 0000000..987acfa --- /dev/null +++ b/lib/cpu_rmap.c @@ -0,0 +1,269 @@ +/* + * cpu_rmap.c: CPU affinity reverse-map support + * Copyright 2011 Solarflare Communications Inc. + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 as published + * by the Free Software Foundation, incorporated herein by reference. + */ + +#include <linux/cpu_rmap.h> +#ifdef CONFIG_GENERIC_HARDIRQS +#include <linux/interrupt.h> +#endif +#include <linux/module.h> + +/* + * These functions maintain a mapping from CPUs to some ordered set of + * objects with CPU affinities. This can be seen as a reverse-map of + * CPU affinity. However, we do not assume that the object affinities + * cover all CPUs in the system. For those CPUs not directly covered + * by object affinities, we attempt to find a nearest object based on + * CPU topology. + */ + +/** + * alloc_cpu_rmap - allocate CPU affinity reverse-map + * @size: Number of objects to be mapped + * @flags: Allocation flags e.g. %GFP_KERNEL + */ +struct cpu_rmap *alloc_cpu_rmap(unsigned int size, gfp_t flags) +{ + struct cpu_rmap *rmap; + unsigned int cpu; + size_t obj_offset; + + /* This is a silly number of objects, and we use u16 indices. */ + if (size > 0xffff) + return NULL; + + /* Offset of object pointer array from base structure */ + obj_offset = ALIGN(offsetof(struct cpu_rmap, near[nr_cpu_ids]), + sizeof(void *)); + + rmap = kzalloc(obj_offset + size * sizeof(rmap->obj[0]), flags); + if (!rmap) + return NULL; + + rmap->obj = (void **)((char *)rmap + obj_offset); + + /* Initially assign CPUs to objects on a rota, since we have + * no idea where the objects are. Use infinite distance, so + * any object with known distance is preferable. Include the + * CPUs that are not present/online, since we definitely want + * any newly-hotplugged CPUs to have some object assigned. + */ + for_each_possible_cpu(cpu) { + rmap->near[cpu].index = cpu % size; + rmap->near[cpu].dist = CPU_RMAP_DIST_INF; + } + + rmap->size = size; + return rmap; +} +EXPORT_SYMBOL(alloc_cpu_rmap); + +/* Reevaluate nearest object for given CPU, comparing with the given + * neighbours at the given distance. + */ +static bool cpu_rmap_copy_neigh(struct cpu_rmap *rmap, unsigned int cpu, + const struct cpumask *mask, u16 dist) +{ + int neigh; + + for_each_cpu(neigh, mask) { + if (rmap->near[cpu].dist > dist && + rmap->near[neigh].dist <= dist) { + rmap->near[cpu].index = rmap->near[neigh].index; + rmap->near[cpu].dist = dist; + return true; + } + } + return false; +} + +#ifdef DEBUG +static void debug_print_rmap(const struct cpu_rmap *rmap, const char *prefix) +{ + unsigned index; + unsigned int cpu; + + pr_info("cpu_rmap %p, %s:\n", rmap, prefix); + + for_each_possible_cpu(cpu) { + index = rmap->near[cpu].index; + pr_info("cpu %d -> obj %u (distance %u)\n", + cpu, index, rmap->near[cpu].dist); + } +} +#else +static inline void +debug_print_rmap(const struct cpu_rmap *rmap, const char *prefix) +{ +} +#endif + +/** + * cpu_rmap_add - add object to a rmap + * @rmap: CPU rmap allocated with alloc_cpu_rmap() + * @obj: Object to add to rmap + * + * Return index of object. + */ +int cpu_rmap_add(struct cpu_rmap *rmap, void *obj) +{ + u16 index; + + BUG_ON(rmap->used >= rmap->size); + index = rmap->used++; + rmap->obj[index] = obj; + return index; +} +EXPORT_SYMBOL(cpu_rmap_add); + +/** + * cpu_rmap_update - update CPU rmap following a change of object affinity + * @rmap: CPU rmap to update + * @index: Index of object whose affinity changed + * @affinity: New CPU affinity of object + */ +int cpu_rmap_update(struct cpu_rmap *rmap, u16 index, + const struct cpumask *affinity) +{ + cpumask_var_t update_mask; + unsigned int cpu; + + if (unlikely(!zalloc_cpumask_var(&update_mask, GFP_KERNEL))) + return -ENOMEM; + + /* Invalidate distance for all CPUs for which this used to be + * the nearest object. Mark those CPUs for update. + */ + for_each_online_cpu(cpu) { + if (rmap->near[cpu].index == index) { + rmap->near[cpu].dist = CPU_RMAP_DIST_INF; + cpumask_set_cpu(cpu, update_mask); + } + } + + debug_print_rmap(rmap, "after invalidating old distances"); + + /* Set distance to 0 for all CPUs in the new affinity mask. + * Mark all CPUs within their NUMA nodes for update. + */ + for_each_cpu(cpu, affinity) { + rmap->near[cpu].index = index; + rmap->near[cpu].dist = 0; + cpumask_or(update_mask, update_mask, + cpumask_of_node(cpu_to_node(cpu))); + } + + debug_print_rmap(rmap, "after updating neighbours"); + + /* Update distances based on topology */ + for_each_cpu(cpu, update_mask) { + if (cpu_rmap_copy_neigh(rmap, cpu, + topology_thread_cpumask(cpu), 1)) + continue; + if (cpu_rmap_copy_neigh(rmap, cpu, + topology_core_cpumask(cpu), 2)) + continue; + if (cpu_rmap_copy_neigh(rmap, cpu, + cpumask_of_node(cpu_to_node(cpu)), 3)) + continue; + /* We could continue into NUMA node distances, but for now + * we give up. + */ + } + + debug_print_rmap(rmap, "after copying neighbours"); + + free_cpumask_var(update_mask); + return 0; +} +EXPORT_SYMBOL(cpu_rmap_update); + +#ifdef CONFIG_GENERIC_HARDIRQS + +/* Glue between IRQ affinity notifiers and CPU rmaps */ + +struct irq_glue { + struct irq_affinity_notify notify; + struct cpu_rmap *rmap; + u16 index; +}; + +/** + * free_irq_cpu_rmap - free a CPU affinity reverse-map used for IRQs + * @rmap: Reverse-map allocated with alloc_irq_cpu_map(), or %NULL + * + * Must be called in process context, before freeing the IRQs, and + * without holding any locks required by global workqueue items. + */ +void free_irq_cpu_rmap(struct cpu_rmap *rmap) +{ + struct irq_glue *glue; + u16 index; + + if (!rmap) + return; + + for (index = 0; index < rmap->used; index++) { + glue = rmap->obj[index]; + irq_set_affinity_notifier(glue->notify.irq, NULL); + } + irq_run_affinity_notifiers(); + + kfree(rmap); +} +EXPORT_SYMBOL(free_irq_cpu_rmap); + +static void +irq_cpu_rmap_notify(struct irq_affinity_notify *notify, const cpumask_t *mask) +{ + struct irq_glue *glue = + container_of(notify, struct irq_glue, notify); + int rc; + + rc = cpu_rmap_update(glue->rmap, glue->index, mask); + if (rc) + pr_warning("irq_cpu_rmap_notify: update failed: %d\n", rc); +} + +static void irq_cpu_rmap_release(struct kref *ref) +{ + struct irq_glue *glue = + container_of(ref, struct irq_glue, notify.kref); + kfree(glue); +} + +/** + * irq_cpu_rmap_add - add an IRQ to a CPU affinity reverse-map + * @rmap: The reverse-map + * @irq: The IRQ number + * + * This adds an IRQ affinity notifier that will update the reverse-map + * automatically. + * + * Must be called in process context, after the IRQ is allocated but + * before it is bound with request_irq(). + */ +int irq_cpu_rmap_add(struct cpu_rmap *rmap, int irq) +{ + struct irq_glue *glue = kzalloc(sizeof(*glue), GFP_KERNEL); + int rc; + + if (!glue) + return -ENOMEM; + glue->notify.notify = irq_cpu_rmap_notify; + glue->notify.release = irq_cpu_rmap_release; + glue->rmap = rmap; + glue->index = cpu_rmap_add(rmap, glue); + rc = irq_set_affinity_notifier(irq, &glue->notify); + if (rc) + kfree(glue); + return rc; +} +EXPORT_SYMBOL(irq_cpu_rmap_add); + +#endif /* CONFIG_GENERIC_HARDIRQS */ |
