percpu-km.rar_memory

/* * mm/percpu-km.c - kernel memory based chunk allocation * * Copyright (C) 2010 SUSE Linux Products GmbH * Copyright (C) 2010 Tejun Heo <tj@kernel.org> * * This file is released under the GPLv2. * * Chunks are allocated as a contiguous kernel memory using gfp * allocation. This is to be used on nommu architectures. * * To use percpu-km, * * - define CONFIG_NEED_PER_CPU_KM from the arch Kconfig. * * - CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK must not be defined. It's * not compatible with PER_CPU_KM. EMBED_FIRST_CHUNK should work * fine. * * - NUMA is not supported. When setting up the first chunk, * @cpu_distance_fn should be NULL or report all CPUs to be nearer * than or at LOCAL_DISTANCE. * * - It's best if the chunk size is power of two multiple of * PAGE_SIZE. Because each chunk is allocated as a contiguous * kernel memory block using alloc_pages(), memory will be wasted if * chunk size is not aligned. percpu-km code will whine about it. */ #if defined(CONFIG_SMP) && defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK) #error "contiguous percpu allocation is incompatible with paged first chunk" #endif #include <linux/log2.h> static int pcpu_populate_chunk(struct pcpu_chunk *chunk, int page_start, int page_end) { return 0; } static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk, int page_start, int page_end) { /* nada */ } static struct pcpu_chunk *pcpu_create_chunk(void) { const int nr_pages = pcpu_group_sizes[0] >> PAGE_SHIFT; struct pcpu_chunk *chunk; struct page *pages; int i; chunk = pcpu_alloc_chunk(); if (!chunk) return NULL; pages = alloc_pages(GFP_KERNEL, order_base_2(nr_pages)); if (!pages) { pcpu_free_chunk(chunk); return NULL; } for (i = 0; i < nr_pages; i++) pcpu_set_page_chunk(nth_page(pages, i), chunk); chunk->data = pages; chunk->base_addr = page_address(pages) - pcpu_group_offsets[0]; spin_lock_irq(&pcpu_lock); pcpu_chunk_populated(chunk, 0, nr_pages); spin_unlock_irq(&pcpu_lock); return chunk; } static void pcpu_destroy_chunk(struct pcpu_chunk *chunk) { const int nr_pages = pcpu_group_sizes[0] >> PAGE_SHIFT; if (chunk && chunk->data) __free_pages(chunk->data, order_base_2(nr_pages)); pcpu_free_chunk(chunk); } static struct page *pcpu_addr_to_page(void *addr) { return virt_to_page(addr); } static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai) { size_t nr_pages, alloc_pages; /* all units must be in a single group */ if (ai->nr_groups != 1) { printk(KERN_CRIT "percpu: can't handle more than one groups\n"); return -EINVAL; } nr_pages = (ai->groups[0].nr_units * ai->unit_size) >> PAGE_SHIFT; alloc_pages = roundup_pow_of_two(nr_pages); if (alloc_pages > nr_pages) printk(KERN_WARNING "percpu: wasting %zu pages per chunk\n", alloc_pages - nr_pages); return 0; }