diff options
Diffstat (limited to 'kern')
| -rw-r--r-- | kern/slab.c | 153 | ||||
| -rw-r--r-- | kern/slab.h | 3 |
2 files changed, 93 insertions, 63 deletions
diff --git a/kern/slab.c b/kern/slab.c index e5e44f40..8d01124d 100644 --- a/kern/slab.c +++ b/kern/slab.c @@ -58,15 +58,10 @@ * over a hash table. Unlike a hash table, a BST provides a "lookup nearest" * operation, so obtaining the slab data (whether it is embedded in the slab or * off slab) from a buffer address simply consists of a "lookup nearest towards - * 0" tree search. Storing slabs instead of buffers also considerably reduces - * the number of elements to retain. Finally, a self-balancing tree is a true - * self-scaling data structure, whereas a hash table requires periodic - * maintenance and complete resizing, which is expensive. The only drawback is - * that releasing a buffer to the slab layer takes logarithmic time instead of - * constant time. But as the data set size is kept reasonable (because slabs - * are stored instead of buffers) and because the CPU pool layer services most - * requests, avoiding many accesses to the slab layer, it is considered an - * acceptable tradeoff. + * 0" tree search. Finally, a self-balancing tree is a true self-scaling data + * structure, whereas a hash table requires periodic maintenance and complete + * resizing, which is expensive. The only drawback is that releasing a buffer + * to the slab layer takes logarithmic time instead of constant time. * * This implementation uses per-cpu pools of objects, which service most * allocation requests. These pools act as caches (but are named differently @@ -200,9 +195,9 @@ * * The flags don't change once set and can be tested without locking. */ -#define KMEM_CF_SLAB_EXTERNAL 0x02 /* Slab data is off slab */ -#define KMEM_CF_VERIFY 0x08 /* Debugging facilities enabled */ -#define KMEM_CF_DIRECT 0x10 /* No buf-to-slab tree lookup */ +#define KMEM_CF_SLAB_EXTERNAL 0x1 /* Slab data is off slab */ +#define KMEM_CF_DIRECTMAP 0x2 /* Allocate from physical memory */ +#define KMEM_CF_VERIFY 0x4 /* Debugging facilities enabled */ /* * Options for kmem_cache_alloc_verify(). @@ -359,27 +354,76 @@ static inline void * kmem_bufctl_to_buf(union kmem_bufctl *bufctl, return (void *)bufctl - cache->bufctl_dist; } -static struct vm_page * -kmem_pagealloc(vm_size_t size) +static vm_offset_t +kmem_pagealloc_directmap(vm_size_t size) { struct vm_page *page; + assert(size == PAGE_SIZE); + for (;;) { page = vm_page_grab_contig(size, VM_PAGE_SEL_DIRECTMAP); if (page != NULL) - return page; + break; VM_PAGE_WAIT(NULL); } + + return phystokv(vm_page_to_pa(page)); } static void -kmem_pagefree(struct vm_page *page, vm_size_t size) +kmem_pagefree_directmap(vm_offset_t addr, vm_size_t size) { + struct vm_page *page; + + assert(size == PAGE_SIZE); + page = vm_page_lookup_pa(kvtophys(addr)); + assert(page != NULL); vm_page_free_contig(page, size); } +static vm_offset_t +kmem_pagealloc_virtual(vm_size_t size) +{ + vm_offset_t addr; + kern_return_t kr; + + assert(size > PAGE_SIZE); + size = vm_page_round(size); + kr = kmem_alloc_wired(kernel_map, &addr, size); + + if (kr != KERN_SUCCESS) + return 0; + + return addr; +} + +static void +kmem_pagefree_virtual(vm_offset_t addr, vm_size_t size) +{ + assert(size > PAGE_SIZE); + size = vm_page_round(size); + kmem_free(kernel_map, addr, size); +} + +static vm_offset_t +kmem_pagealloc(vm_size_t size, int flags) +{ + return (flags & KMEM_CF_DIRECTMAP) + ? kmem_pagealloc_directmap(size) + : kmem_pagealloc_virtual(size); +} + +static void +kmem_pagefree(vm_offset_t addr, vm_size_t size, int flags) +{ + return (flags & KMEM_CF_DIRECTMAP) + ? kmem_pagefree_directmap(addr, size) + : kmem_pagefree_virtual(addr, size); +} + static void kmem_slab_create_verify(struct kmem_slab *slab, struct kmem_cache *cache) { @@ -408,25 +452,22 @@ static void kmem_slab_create_verify(struct kmem_slab *slab, static struct kmem_slab * kmem_slab_create(struct kmem_cache *cache, size_t color) { - struct vm_page *page; struct kmem_slab *slab; union kmem_bufctl *bufctl; size_t buf_size; unsigned long buffers; - void *slab_buf; + vm_offset_t slab_buf; - page = kmem_pagealloc(cache->slab_size); + slab_buf = kmem_pagealloc(cache->slab_size, cache->flags); - if (page == NULL) + if (slab_buf == 0) return NULL; - slab_buf = (void *)phystokv(vm_page_to_pa(page)); - if (cache->flags & KMEM_CF_SLAB_EXTERNAL) { slab = (struct kmem_slab *)kmem_cache_alloc(&kmem_slab_cache); if (slab == NULL) { - kmem_pagefree(page, cache->slab_size); + kmem_pagefree(slab_buf, cache->slab_size, cache->flags); return NULL; } } else { @@ -437,7 +478,7 @@ static struct kmem_slab * kmem_slab_create(struct kmem_cache *cache, rbtree_node_init(&slab->tree_node); slab->nr_refs = 0; slab->first_free = NULL; - slab->addr = slab_buf + color; + slab->addr = (void *)(slab_buf + color); buf_size = cache->buf_size; bufctl = kmem_buf_to_bufctl(slab->addr, cache); @@ -487,7 +528,6 @@ static void kmem_slab_destroy_verify(struct kmem_slab *slab, */ static void kmem_slab_destroy(struct kmem_slab *slab, struct kmem_cache *cache) { - struct vm_page *page; vm_offset_t slab_buf; assert(slab->nr_refs == 0); @@ -497,9 +537,7 @@ static void kmem_slab_destroy(struct kmem_slab *slab, struct kmem_cache *cache) kmem_slab_destroy_verify(slab, cache); slab_buf = (vm_offset_t)P2ALIGN((unsigned long)slab->addr, PAGE_SIZE); - page = vm_page_lookup_pa(kvtophys(slab_buf)); - assert(page != NULL); - kmem_pagefree(page, cache->slab_size); + kmem_pagefree(slab_buf, cache->slab_size, cache->flags); if (cache->flags & KMEM_CF_SLAB_EXTERNAL) kmem_cache_free(&kmem_slab_cache, (vm_offset_t)slab); @@ -507,7 +545,7 @@ static void kmem_slab_destroy(struct kmem_slab *slab, struct kmem_cache *cache) static inline int kmem_slab_use_tree(int flags) { - return !(flags & KMEM_CF_DIRECT) || (flags & KMEM_CF_VERIFY); + return (flags & KMEM_CF_SLAB_EXTERNAL) || (flags & KMEM_CF_VERIFY); } static inline int kmem_slab_cmp_lookup(const void *addr, @@ -668,27 +706,20 @@ static void kmem_cache_error(struct kmem_cache *cache, void *buf, int error, * Compute an appropriate slab size for the given cache. * * Once the slab size is known, this function sets the related properties - * (buffers per slab and maximum color). It can also set the KMEM_CF_DIRECT + * (buffers per slab and maximum color). It can also set the KMEM_CF_DIRECTMAP * and/or KMEM_CF_SLAB_EXTERNAL flags depending on the resulting layout. */ static void kmem_cache_compute_sizes(struct kmem_cache *cache, int flags) { size_t size, waste; - unsigned int order; int embed; if (cache->buf_size < KMEM_BUF_SIZE_THRESHOLD) flags |= KMEM_CACHE_NOOFFSLAB; - /* - * 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); + cache->slab_size = PAGE_SIZE; for (;;) { - cache->slab_size = PAGE_SIZE << order; - if (flags & KMEM_CACHE_NOOFFSLAB) embed = 1; else { @@ -704,7 +735,7 @@ static void kmem_cache_compute_sizes(struct kmem_cache *cache, int flags) if (size >= cache->buf_size) break; - order++; + cache->slab_size += PAGE_SIZE; } cache->bufs_per_slab = size / cache->buf_size; @@ -713,11 +744,19 @@ static void kmem_cache_compute_sizes(struct kmem_cache *cache, int flags) if (cache->color_max >= PAGE_SIZE) cache->color_max = PAGE_SIZE - 1; - if (embed) { - if (cache->slab_size == PAGE_SIZE) - cache->flags |= KMEM_CF_DIRECT; - } else { + if (!embed) cache->flags |= KMEM_CF_SLAB_EXTERNAL; + + if ((flags & KMEM_CACHE_DIRECTMAP) || (cache->slab_size == PAGE_SIZE)) { + cache->flags |= KMEM_CF_DIRECTMAP; + + /* + * Avoid using larger-than-page slabs backed by the direct physical + * mapping to completely prevent physical memory fragmentation from + * making slab allocations fail. + */ + if (cache->slab_size != PAGE_SIZE) + panic("slab: invalid cache parameters"); } } @@ -928,11 +967,7 @@ static void kmem_cache_free_to_slab(struct kmem_cache *cache, void *buf) struct kmem_slab *slab; union kmem_bufctl *bufctl; - if (cache->flags & KMEM_CF_DIRECT) { - assert(cache->slab_size == PAGE_SIZE); - slab = (struct kmem_slab *)P2END((unsigned long)buf, cache->slab_size) - - 1; - } else { + if (cache->flags & KMEM_CF_SLAB_EXTERNAL) { struct rbtree_node *node; node = rbtree_lookup_nearest(&cache->active_slabs, buf, @@ -941,6 +976,10 @@ static void kmem_cache_free_to_slab(struct kmem_cache *cache, void *buf) slab = rbtree_entry(node, struct kmem_slab, tree_node); assert((unsigned long)buf < (P2ALIGN((unsigned long)slab->addr + cache->slab_size, PAGE_SIZE))); + } else { + assert(cache->slab_size == PAGE_SIZE); + slab = (struct kmem_slab *)P2END((unsigned long)buf, cache->slab_size) + - 1; } assert(slab->nr_refs >= 1); @@ -1243,7 +1282,7 @@ void slab_init(void) * Prevent off slab data for the slab cache to avoid infinite recursion. */ kmem_cache_init(&kmem_slab_cache, "kmem_slab", sizeof(struct kmem_slab), - 0, NULL, KMEM_CACHE_NOOFFSLAB); + 0, NULL, KMEM_CACHE_NOOFFSLAB | KMEM_CACHE_DIRECTMAP); } void kalloc_init(void) @@ -1307,14 +1346,7 @@ vm_offset_t kalloc(vm_size_t size) if ((buf != 0) && (cache->flags & KMEM_CF_VERIFY)) kalloc_verify(cache, buf, size); } else { - struct vm_page *page; - - page = kmem_pagealloc(size); - - if (page == NULL) - return 0; - - buf = (void *)phystokv(vm_page_to_pa(page)); + buf = (void *)kmem_pagealloc_virtual(size); } return (vm_offset_t)buf; @@ -1356,10 +1388,7 @@ void kfree(vm_offset_t data, vm_size_t size) kmem_cache_free(cache, data); } else { - struct vm_page *page; - - page = vm_page_lookup_pa(kvtophys(data)); - kmem_pagefree(page, size); + kmem_pagefree_virtual(data, size); } } @@ -1463,7 +1492,7 @@ kern_return_t host_slab_info(host_t host, cache_info_array_t *infop, ? CACHE_FLAGS_SLAB_EXTERNAL : 0) | ((cache->flags & KMEM_CF_VERIFY) ? CACHE_FLAGS_VERIFY : 0) - | ((cache->flags & KMEM_CF_DIRECT) + | ((cache->flags & KMEM_CF_DIRECTMAP) ? CACHE_FLAGS_DIRECT : 0); #if SLAB_USE_CPU_POOLS info[i].cpu_pool_size = cache->cpu_pool_type->array_size; diff --git a/kern/slab.h b/kern/slab.h index 51f29a90..a9978fdb 100644 --- a/kern/slab.h +++ b/kern/slab.h @@ -196,7 +196,8 @@ typedef struct kmem_cache *kmem_cache_t; * Cache initialization flags. */ #define KMEM_CACHE_NOOFFSLAB 0x1 /* Don't allocate external slab data */ -#define KMEM_CACHE_VERIFY 0x2 /* Use debugging facilities */ +#define KMEM_CACHE_DIRECTMAP 0x2 /* Allocate from physical memory */ +#define KMEM_CACHE_VERIFY 0x4 /* Use debugging facilities */ /* * Initialize a cache. |