forked from Minki/linux
30a5b5367e
There is limited visibility into the use of percpu memory leaving us unable to reason about correctness of parameters and overall use of percpu memory. These counters and statistics aim to help understand basic statistics about percpu memory such as number of allocations over the lifetime, allocation sizes, and fragmentation. New Config: PERCPU_STATS Signed-off-by: Dennis Zhou <dennisz@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>
115 lines
2.8 KiB
C
115 lines
2.8 KiB
C
/*
|
|
* 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);
|
|
|
|
pcpu_stats_chunk_alloc();
|
|
|
|
return chunk;
|
|
}
|
|
|
|
static void pcpu_destroy_chunk(struct pcpu_chunk *chunk)
|
|
{
|
|
const int nr_pages = pcpu_group_sizes[0] >> PAGE_SHIFT;
|
|
|
|
pcpu_stats_chunk_dealloc();
|
|
|
|
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) {
|
|
pr_crit("can't handle more than one group\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)
|
|
pr_warn("wasting %zu pages per chunk\n",
|
|
alloc_pages - nr_pages);
|
|
|
|
return 0;
|
|
}
|