diff options
| -rw-r--r-- | kern/slab.c | 82 |
1 files changed, 26 insertions, 56 deletions
diff --git a/kern/slab.c b/kern/slab.c index f1a534a8..d18c10b4 100644 --- a/kern/slab.c +++ b/kern/slab.c @@ -112,19 +112,6 @@ #define KMEM_ALIGN_MIN 8 /* - * Minimum number of buffers per slab. - * - * This value is ignored when the slab size exceeds a threshold. - */ -#define KMEM_MIN_BUFS_PER_SLAB 8 - -/* - * Special slab size beyond which the minimum number of buffers per slab is - * ignored when computing the slab size of a cache. - */ -#define KMEM_SLAB_SIZE_THRESHOLD (8 * PAGE_SIZE) - -/* * Special buffer size under which slab data is unconditionnally allocated * from its associated slab. */ @@ -697,64 +684,47 @@ static void kmem_cache_error(struct kmem_cache *cache, void *buf, int error, */ static void kmem_cache_compute_sizes(struct kmem_cache *cache, int flags) { - size_t i, buffers, buf_size, slab_size, free_slab_size; - size_t waste, waste_min, optimal_size = optimal_size; - int embed, optimal_embed = optimal_embed; - unsigned int slab_order; + size_t size, waste; + unsigned int order; + int embed; - buf_size = cache->buf_size; - - if (buf_size < KMEM_BUF_SIZE_THRESHOLD) + if (cache->buf_size < KMEM_BUF_SIZE_THRESHOLD) flags |= KMEM_CACHE_NOOFFSLAB; - i = 0; - waste_min = (size_t)-1; - - do { - i++; - - slab_order = vm_page_order(i * buf_size); - slab_size = PAGE_SIZE << slab_order; - free_slab_size = slab_size; - - if (flags & KMEM_CACHE_NOOFFSLAB) - free_slab_size -= sizeof(struct kmem_slab); - - buffers = free_slab_size / buf_size; - waste = free_slab_size % buf_size; + /* + * In order to cope with physical memory fragmentation, the slab size is + * chosen as the lowest possible allocation order. + */ + order = vm_page_order(cache->buf_size); - if (buffers > i) - i = buffers; + for (;;) { + cache->slab_size = PAGE_SIZE << order; if (flags & KMEM_CACHE_NOOFFSLAB) embed = 1; - else if (sizeof(struct kmem_slab) <= waste) { - embed = 1; - waste -= sizeof(struct kmem_slab); - } else { - embed = 0; + else { + waste = cache->slab_size % cache->buf_size; + embed = (sizeof(struct kmem_slab) <= waste); } - if (waste <= waste_min) { - waste_min = waste; - optimal_size = slab_size; - optimal_embed = embed; - } - } while ((buffers < KMEM_MIN_BUFS_PER_SLAB) - && (slab_size < KMEM_SLAB_SIZE_THRESHOLD)); + size = cache->slab_size; + + if (embed) + size -= sizeof(struct kmem_slab); - assert(!(flags & KMEM_CACHE_NOOFFSLAB) || optimal_embed); + if (size >= cache->buf_size) + break; + + order++; + } - cache->slab_size = optimal_size; - slab_size = cache->slab_size - - (optimal_embed ? sizeof(struct kmem_slab) : 0); - cache->bufs_per_slab = slab_size / buf_size; - cache->color_max = slab_size % buf_size; + cache->bufs_per_slab = size / cache->buf_size; + cache->color_max = size % cache->buf_size; if (cache->color_max >= PAGE_SIZE) cache->color_max = PAGE_SIZE - 1; - if (optimal_embed) { + if (embed) { if (cache->slab_size == PAGE_SIZE) cache->flags |= KMEM_CF_DIRECT; } else { |