>From 159d74b5a8f3d0f07e18ddad74b7025cf17dcc69 Mon Sep 17 00:00:00 2001 From: Yinghao Xie <yinghao.xie@xxxxxxxxxxx> Date: Thu, 19 Mar 2015 19:32:25 +0800 Subject: [PATCH] mm/zsmalloc.c: count in handle's size when calculating size_class's pages_per_zspage 1. Fix wastage calculation; 2. Indirect handle introduced extra ZS_HANDLE_SIZE size for each object,it's transparent for upper function, but a size_class's total objects will changed: take the 43rd class which class_size = 32 + 43 * 16 = 720 as example: 4096 * 1 % 720 = 496 4096 * 2 % 720 = 272 4096 * 3 % 720 = 48 4096 * 4 %720 = 544 after handle introduced,class_size + ZS_HANDLE_SIZE (4 on 32bit) = 724 4096 * 1 % 724 = 476 4096 * 2 % 724 = 228 4096 * 3 % 724 = 704 4096 * 4 % 724 = 456 Clearly, ZS_HANDLE_SIZE should be considered when calculating pages_per_zspage; 3. in get_size_class_index(), min(zs_size_classes - 1, idx) insures a huge class's index <= zs_size_classes - 1, so it's no need to check again; Signed-off-by: Yinghao Xie <yinghao.xie@xxxxxxxxxxx> --- mm/zsmalloc.c | 15 ++++++--------- 1 file changed, 6 insertions(+), 9 deletions(-) diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c index 461243e..64c379b 100644 --- a/mm/zsmalloc.c +++ b/mm/zsmalloc.c @@ -760,7 +760,8 @@ out: * to form a zspage for each size class. This is important * to reduce wastage due to unusable space left at end of * each zspage which is given as: - * wastage = Zp - Zp % size_class + * wastage = Zp % (class_size + ZS_HANDLE_SIZE) + * usage = Zp - wastage * where Zp = zspage size = k * PAGE_SIZE where k = 1, 2, ... * * For example, for size class of 3/8 * PAGE_SIZE, we should @@ -773,6 +774,9 @@ static int get_pages_per_zspage(int class_size) /* zspage order which gives maximum used size per KB */ int max_usedpc_order = 1; + if (class_size > ZS_MAX_ALLOC_SIZE) + class_size = ZS_MAX_ALLOC_SIZE; + for (i = 1; i <= ZS_MAX_PAGES_PER_ZSPAGE; i++) { int zspage_size; int waste, usedpc; @@ -1426,11 +1430,6 @@ unsigned long zs_malloc(struct zs_pool *pool, size_t size) /* extra space in chunk to keep the handle */ size += ZS_HANDLE_SIZE; class = pool->size_class[get_size_class_index(size)]; - /* In huge class size, we store the handle into first_page->private */ - if (class->huge) { - size -= ZS_HANDLE_SIZE; - class = pool->size_class[get_size_class_index(size)]; - } spin_lock(&class->lock); first_page = find_get_zspage(class); @@ -1856,9 +1855,7 @@ struct zs_pool *zs_create_pool(char *name, gfp_t flags) struct size_class *class; size = ZS_MIN_ALLOC_SIZE + i * ZS_SIZE_CLASS_DELTA; - if (size > ZS_MAX_ALLOC_SIZE) - size = ZS_MAX_ALLOC_SIZE; - pages_per_zspage = get_pages_per_zspage(size); + pages_per_zspage = get_pages_per_zspage(size + ZS_HANDLE_SIZE); /* * size_class is used for normal zsmalloc operation such -- 1.7.9.5 ��.n������g����a����&ޖ)���)��h���&������梷�����Ǟ�m������)������^�����������v���O��zf������