diff options
| -rw-r--r-- | mm/z3fold.c | 185 |
1 files changed, 145 insertions, 40 deletions
diff --git a/mm/z3fold.c b/mm/z3fold.c index 29a4f1249bef..bebc10083f1c 100644 --- a/mm/z3fold.c +++ b/mm/z3fold.c @@ -34,6 +34,29 @@ #include <linux/spinlock.h> #include <linux/zpool.h> +/* + * NCHUNKS_ORDER determines the internal allocation granularity, effectively + * adjusting internal fragmentation. It also determines the number of + * freelists maintained in each pool. NCHUNKS_ORDER of 6 means that the + * allocation granularity will be in chunks of size PAGE_SIZE/64. Some chunks + * in the beginning of an allocated page are occupied by z3fold header, so + * NCHUNKS will be calculated to 63 (or 62 in case CONFIG_DEBUG_SPINLOCK=y), + * which shows the max number of free chunks in z3fold page, also there will + * be 63, or 62, respectively, freelists per pool. + */ +#define NCHUNKS_ORDER 6 + +#define CHUNK_SHIFT (PAGE_SHIFT - NCHUNKS_ORDER) +#define CHUNK_SIZE (1 << CHUNK_SHIFT) +#define ZHDR_SIZE_ALIGNED round_up(sizeof(struct z3fold_header), CHUNK_SIZE) +#define ZHDR_CHUNKS (ZHDR_SIZE_ALIGNED >> CHUNK_SHIFT) +#define TOTAL_CHUNKS (PAGE_SIZE >> CHUNK_SHIFT) +#define NCHUNKS ((PAGE_SIZE - ZHDR_SIZE_ALIGNED) >> CHUNK_SHIFT) + +#define BUDDY_MASK (0x3) +#define BUDDY_SHIFT 2 +#define SLOTS_ALIGN (0x40) + /***************** * Structures *****************/ @@ -47,9 +70,19 @@ enum buddy { FIRST, MIDDLE, LAST, - BUDDIES_MAX + BUDDIES_MAX = LAST }; +struct z3fold_buddy_slots { + /* + * we are using BUDDY_MASK in handle_to_buddy etc. so there should + * be enough slots to hold all possible variants + */ + unsigned long slot[BUDDY_MASK + 1]; + unsigned long pool; /* back link + flags */ +}; +#define HANDLE_FLAG_MASK (0x03) + /* * struct z3fold_header - z3fold page metadata occupying first chunks of each * z3fold page, except for HEADLESS pages @@ -58,7 +91,7 @@ enum buddy { * @page_lock: per-page lock * @refcount: reference count for the z3fold page * @work: work_struct for page layout optimization - * @pool: pointer to the pool which this page belongs to + * @slots: pointer to the structure holding buddy slots * @cpu: CPU which this page "belongs" to * @first_chunks: the size of the first buddy in chunks, 0 if free * @middle_chunks: the size of the middle buddy in chunks, 0 if free @@ -70,7 +103,7 @@ struct z3fold_header { spinlock_t page_lock; struct kref refcount; struct work_struct work; - struct z3fold_pool *pool; + struct z3fold_buddy_slots *slots; short cpu; unsigned short first_chunks; unsigned short middle_chunks; @@ -79,28 +112,6 @@ struct z3fold_header { unsigned short first_num:2; }; -/* - * NCHUNKS_ORDER determines the internal allocation granularity, effectively - * adjusting internal fragmentation. It also determines the number of - * freelists maintained in each pool. NCHUNKS_ORDER of 6 means that the - * allocation granularity will be in chunks of size PAGE_SIZE/64. Some chunks - * in the beginning of an allocated page are occupied by z3fold header, so - * NCHUNKS will be calculated to 63 (or 62 in case CONFIG_DEBUG_SPINLOCK=y), - * which shows the max number of free chunks in z3fold page, also there will - * be 63, or 62, respectively, freelists per pool. - */ -#define NCHUNKS_ORDER 6 - -#define CHUNK_SHIFT (PAGE_SHIFT - NCHUNKS_ORDER) -#define CHUNK_SIZE (1 << CHUNK_SHIFT) -#define ZHDR_SIZE_ALIGNED round_up(sizeof(struct z3fold_header), CHUNK_SIZE) -#define ZHDR_CHUNKS (ZHDR_SIZE_ALIGNED >> CHUNK_SHIFT) -#define TOTAL_CHUNKS (PAGE_SIZE >> CHUNK_SHIFT) -#define NCHUNKS ((PAGE_SIZE - ZHDR_SIZE_ALIGNED) >> CHUNK_SHIFT) - -#define BUDDY_MASK (0x3) -#define BUDDY_SHIFT 2 - /** * struct z3fold_pool - stores metadata for each z3fold pool * @name: pool name @@ -113,6 +124,7 @@ struct z3fold_header { * added buddy. * @stale: list of pages marked for freeing * @pages_nr: number of z3fold pages in the pool. + * @c_handle: cache for z3fold_buddy_slots allocation * @ops: pointer to a structure of user defined operations specified at * pool creation time. * @compact_wq: workqueue for page layout background optimization @@ -130,6 +142,7 @@ struct z3fold_pool { struct list_head lru; struct list_head stale; atomic64_t pages_nr; + struct kmem_cache *c_handle; const struct z3fold_ops *ops; struct zpool *zpool; const struct zpool_ops *zpool_ops; @@ -164,11 +177,65 @@ static int size_to_chunks(size_t size) static void compact_page_work(struct work_struct *w); +static inline struct z3fold_buddy_slots *alloc_slots(struct z3fold_pool *pool) +{ + struct z3fold_buddy_slots *slots = kmem_cache_alloc(pool->c_handle, + GFP_KERNEL); + + if (slots) { + memset(slots->slot, 0, sizeof(slots->slot)); + slots->pool = (unsigned long)pool; + } + + return slots; +} + +static inline struct z3fold_pool *slots_to_pool(struct z3fold_buddy_slots *s) +{ + return (struct z3fold_pool *)(s->pool & ~HANDLE_FLAG_MASK); +} + +static inline struct z3fold_buddy_slots *handle_to_slots(unsigned long handle) +{ + return (struct z3fold_buddy_slots *)(handle & ~(SLOTS_ALIGN - 1)); +} + +static inline void free_handle(unsigned long handle) +{ + struct z3fold_buddy_slots *slots; + int i; + bool is_free; + + if (handle & (1 << PAGE_HEADLESS)) + return; + + WARN_ON(*(unsigned long *)handle == 0); + *(unsigned long *)handle = 0; + slots = handle_to_slots(handle); + is_free = true; + for (i = 0; i <= BUDDY_MASK; i++) { + if (slots->slot[i]) { + is_free = false; + break; + } + } + + if (is_free) { + struct z3fold_pool *pool = slots_to_pool(slots); + + kmem_cache_free(pool->c_handle, slots); + } +} + /* Initializes the z3fold header of a newly allocated z3fold page */ static struct z3fold_header *init_z3fold_page(struct page *page, struct z3fold_pool *pool) { struct z3fold_header *zhdr = page_address(page); + struct z3fold_buddy_slots *slots = alloc_slots(pool); + + if (!slots) + return NULL; INIT_LIST_HEAD(&page->lru); clear_bit(PAGE_HEADLESS, &page->private); @@ -185,7 +252,7 @@ static struct z3fold_header *init_z3fold_page(struct page *page, zhdr->first_num = 0; zhdr->start_middle = 0; zhdr->cpu = -1; - zhdr->pool = pool; + zhdr->slots = slots; INIT_LIST_HEAD(&zhdr->buddy); INIT_WORK(&zhdr->work, compact_page_work); return zhdr; @@ -215,33 +282,57 @@ static inline void z3fold_page_unlock(struct z3fold_header *zhdr) spin_unlock(&zhdr->page_lock); } +/* Helper function to build the index */ +static inline int __idx(struct z3fold_header *zhdr, enum buddy bud) +{ + return (bud + zhdr->first_num) & BUDDY_MASK; +} + /* * Encodes the handle of a particular buddy within a z3fold page * Pool lock should be held as this function accesses first_num */ static unsigned long encode_handle(struct z3fold_header *zhdr, enum buddy bud) { - unsigned long handle; + struct z3fold_buddy_slots *slots; + unsigned long h = (unsigned long)zhdr; + int idx = 0; - handle = (unsigned long)zhdr; - if (bud != HEADLESS) { - handle |= (bud + zhdr->first_num) & BUDDY_MASK; - if (bud == LAST) - handle |= (zhdr->last_chunks << BUDDY_SHIFT); - } - return handle; + /* + * For a headless page, its handle is its pointer with the extra + * PAGE_HEADLESS bit set + */ + if (bud == HEADLESS) + return h | (1 << PAGE_HEADLESS); + + /* otherwise, return pointer to encoded handle */ + idx = __idx(zhdr, bud); + h += idx; + if (bud == LAST) + h |= (zhdr->last_chunks << BUDDY_SHIFT); + + slots = zhdr->slots; + slots->slot[idx] = h; + return (unsigned long)&slots->slot[idx]; } /* Returns the z3fold page where a given handle is stored */ -static struct z3fold_header *handle_to_z3fold_header(unsigned long handle) +static inline struct z3fold_header *handle_to_z3fold_header(unsigned long handle) { - return (struct z3fold_header *)(handle & PAGE_MASK); + unsigned long addr = handle; + + if (!(addr & (1 << PAGE_HEADLESS))) + addr = *(unsigned long *)handle; + + return (struct z3fold_header *)(addr & PAGE_MASK); } /* only for LAST bud, returns zero otherwise */ static unsigned short handle_to_chunks(unsigned long handle) { - return (handle & ~PAGE_MASK) >> BUDDY_SHIFT; + unsigned long addr = *(unsigned long *)handle; + + return (addr & ~PAGE_MASK) >> BUDDY_SHIFT; } /* @@ -251,13 +342,18 @@ static unsigned short handle_to_chunks(unsigned long handle) */ static enum buddy handle_to_buddy(unsigned long handle) { - struct z3fold_header *zhdr = handle_to_z3fold_header(handle); - return (handle - zhdr->first_num) & BUDDY_MASK; + struct z3fold_header *zhdr; + unsigned long addr; + + WARN_ON(handle & (1 << PAGE_HEADLESS)); + addr = *(unsigned long *)handle; + zhdr = (struct z3fold_header *)(addr & PAGE_MASK); + return (addr - zhdr->first_num) & BUDDY_MASK; } static inline struct z3fold_pool *zhdr_to_pool(struct z3fold_header *zhdr) { - return zhdr->pool; + return slots_to_pool(zhdr->slots); } static void __release_z3fold_page(struct z3fold_header *zhdr, bool locked) @@ -583,6 +679,11 @@ static struct z3fold_pool *z3fold_create_pool(const char *name, gfp_t gfp, pool = kzalloc(sizeof(struct z3fold_pool), gfp); if (!pool) goto out; + pool->c_handle = kmem_cache_create("z3fold_handle", + sizeof(struct z3fold_buddy_slots), + SLOTS_ALIGN, 0, NULL); + if (!pool->c_handle) + goto out_c; spin_lock_init(&pool->lock); spin_lock_init(&pool->stale_lock); pool->unbuddied = __alloc_percpu(sizeof(struct list_head)*NCHUNKS, 2); @@ -613,6 +714,8 @@ out_wq: out_unbuddied: free_percpu(pool->unbuddied); out_pool: + kmem_cache_destroy(pool->c_handle); +out_c: kfree(pool); out: return NULL; @@ -626,6 +729,7 @@ out: */ static void z3fold_destroy_pool(struct z3fold_pool *pool) { + kmem_cache_destroy(pool->c_handle); destroy_workqueue(pool->release_wq); destroy_workqueue(pool->compact_wq); kfree(pool); @@ -818,6 +922,7 @@ static void z3fold_free(struct z3fold_pool *pool, unsigned long handle) return; } + free_handle(handle); if (kref_put(&zhdr->refcount, release_z3fold_page_locked_list)) { atomic64_dec(&pool->pages_nr); return; |