{"id":3669,"date":"2012-01-04T22:52:03","date_gmt":"2012-01-04T14:52:03","guid":{"rendered":"http:\/\/edsionte.com\/techblog\/?p=3669"},"modified":"2012-05-03T17:19:23","modified_gmt":"2012-05-03T09:19:23","slug":"%e5%86%85%e5%ad%98%e7%ae%a1%e7%90%86%e5%99%a8api","status":"publish","type":"post","link":"http:\/\/edsionte.com\/techblog\/archives\/3669","title":{"rendered":"\u8bf7\u6c42\u9875\u6846API\u7b80\u4ecb"},"content":{"rendered":"

\u5728\u7528\u6237\u6001\u4e0b\u7a0b\u5e8f\u4e2d\uff0c\u6211\u4eec\u53ef\u4ee5\u901a\u8fc7malloc()\u52a8\u6001\u7533\u8bf7\u5185\u5b58\u7a7a\u95f4\u3002\u5728\u5185\u6838\u7a7a\u95f4\u4e2d\uff0c\u4e13\u95e8\u6709\u4e00\u4e2a\u5185\u6838\u5b50\u7cfb\u7edf\u5904\u7406\u5bf9\u8fde\u7eed\u9875\u6846\u7684\u5185\u5b58\u5206\u914d\u8bf7\u6c42\uff0c\u8fd9\u4e2a\u5185\u6838\u5b50\u7cfb\u7edf\u5373\u4e3a\u7ba1\u7406\u533a\u9875\u6846\u5206\u914d\u5668\uff08zoned page frame allocator\uff09\u3002\u8be5\u5206\u914d\u5668\u5305\u542b\u516d\u4e2a\u4e13\u95e8\u7528\u4e8e\u5206\u914d\u9875\u6846\u7684API\uff0c\u8fd9\u4e9bAPI\u90fd\u662f\u57fa\u4e8e\u4f19\u4f34\u7b97\u6cd5\u800c\u5b9e\u73b0\u7684\uff0c\u56e0\u6b64\u8fd9\u4e9bAPI\u7533\u8bf7\u7684\u9875\u6846\u6570\u53ea\u80fd\u4e3a2\u7684\u6574\u6570\u5e42\u5927\u5c0f\u3002<\/p>\n

\u5185\u5b58\u5206\u914d\u5668API<\/h3>\n

1.alloc_pages()<\/strong><\/p>\n

\u8be5\u5b8f\u7528\u6765\u5206\u914d2\u7684order\u6b21\u65b9\u4e2a\u8fde\u7eed\u7684\u9875\u6846\uff0c\u5982\u679c\u7533\u8bf7\u6210\u529f\u8fd4\u56de\u7b2c\u4e00\u4e2a\u6240\u5206\u914d\u9875\u6846\u7684\u63cf\u8ff0\u7b26\u5730\u5740\uff0c\u7533\u8bf7\u5931\u8d25\u7684\u8bdd\u8fd4\u56deNULL\u3002<\/p>\n

#define alloc_pages(gfp_mask, order) \\\r\n                alloc_pages_node(numa_node_id(), gfp_mask, order)<\/pre>\n
2.alloc_page()<\/strong><\/p>\n
\u8be5\u51fd\u6570\u7528\u6765\u5206\u914d\u4e00\u4e2a\u5355\u72ec\u7684\u9875\u6846\uff0c\u5b83\u53ef\u4ee5\u770b\u4f5c\u662falloc_pages()\u5f53order\u7b49\u4e8e0\u65f6\u7684\u7279\u6b8a\u60c5\u51b5\u3002<\/p>\n
#define alloc_page(gfp_mask) alloc_pages(gfp_mask, 0)<\/pre>\n
3.__get_free_pages()<\/strong><\/p>\n
\u901a\u8fc7\u8be5\u51fd\u6570\u53ef\u4ee5\u7533\u8bf7\u957f\u4e3a2\u7684order\u6b21\u65b9\u5927\u5c0f\u7684\u8fde\u7eed\u9875\u6846\uff0c\u4f46\u662f\u5b83\u8fd4\u56de\u7684\u662f\u8fd9\u6bb5\u8fde\u7eed\u9875\u6846\u4e2d\u7b2c\u4e00\u4e2a\u9875\u6240\u5bf9\u5e94\u7684\u7ebf\u6027\u5730\u5740\u3002\u4ece\u6e90\u7801\u4e2d\u53ef\u4ee5\u770b\u51fa\uff0c\u8be5\u51fd\u6570\u5185\u90e8\u4ecd\u7136\u8c03\u7528\u4e86alloc_pages\u51fd\u6570\uff0c\u5e76\u5229\u7528page_address\u51fd\u6570\u5c06\u9875\u63cf\u8ff0\u7b26\u5730\u5740\u8f6c\u6362\u4e3a\u7ebf\u6027\u5730\u5740\u3002<\/p>\n
unsigned long __get_free_pages(gfp_t gfp_mask, unsigned int order)\r\n{\r\n        struct page *page;\r\n\r\n        VM_BUG_ON((gfp_mask & __GFP_HIGHMEM) != 0);\r\n\r\n        page = alloc_pages(gfp_mask, order);\r\n        if (!page)\r\n                return 0;\r\n        return (unsigned long) page_address(page);\r\n}<\/pre>\n
4.__get_free_page()<\/strong><\/p>\n
\u8be5\u5b8f\u53ef\u4ee5\u770b\u4f5c\u662f__get_free_pages\u51fd\u6570\u7684\u7279\u6b8a\u60c5\u51b5\uff0c\u5b83\u7528\u4e8e\u7533\u8bf7\u4e00\u4e2a\u5355\u72ec\u7684\u9875\u6846\u3002<\/p>\n
#define __get_free_page(gfp_mask) \\\r\n        __get_free_pages((gfp_mask),0)<\/pre>\n
5.get_zeroed_page()<\/strong><\/p>\n
\u8be5\u51fd\u6570\u7528\u6765\u83b7\u53d6\u4e00\u4e2a\u586b\u6ee10\u7684\u9875\u6846\uff0c\u5176\u4e2d__GFP_ZERO\u53c2\u6570\u7528\u6765\u4f53\u73b0\u8fd9\u4e00\u70b9\u3002<\/p>\n
unsigned long get_zeroed_page(gfp_t gfp_mask)\r\n{\r\n        return __get_free_pages(gfp_mask | __GFP_ZERO, 0);\r\n}<\/pre>\n
6.__get_dma_pages()<\/strong><\/p>\n
\u8be5\u5b8f\u83b7\u5f97\u7684\u9875\u6846\u7528\u4e8eDMA\u64cd\u4f5c\u3002<\/p>\n
#define (gfp_mask, order) \\\r\n                __get_free_pages((gfp_mask) | GFP_DMA,(order))<\/pre>\n
\u8bf7\u6c42\u9875\u6846\u7684\u6807\u5fd7<\/h3>\n
\u4ece\u4e0a\u8ff0\u51e0\u4e2a\u5206\u914d\u5668API\u4e2d\u53ef\u4ee5\u770b\u5230\uff0c\u9664\u4e86\u7528\u4e8e\u6307\u793a\u8bf7\u6c42\u9875\u6846\u5927\u5c0f\u7684order\u53c2\u6570\u5916\uff0c\u8fd8\u5305\u62ec\u4e00\u7ec4\u6807\u5fd7gfp_mask\uff0c\u5b83\u6307\u660e\u4e86\u5982\u4f55\u5bfb\u627e\u7a7a\u95f2\u7684\u9875\u6846\u3002\u4e0b\u9762\u4ec5\u8bf4\u660e\u51e0\u4e2a\u5e38\u89c1\u7684\u5206\u914d\u6807\u5fd7\u3002<\/p>\n
__GFP_DMA:\u8be5\u6807\u5fd7\u6307\u660e\u53ea\u80fd\u4eceZONE_DMA\u5185\u5b58\u7ba1\u7406\u533a\u83b7\u5f97\u9875\u6846\u3002<\/p>\n
__GFP_HIGHMEM:\u5982\u679c\u8be5\u6807\u5fd7\u88ab\u8bbe\u7f6e\uff0c\u5219\u6309\u7167ZONE_HIGHMEM,ZONE_NORMAL\u548cZONE_DMA\u7684\u8bf7\u6c42\u987a\u5e8f\u83b7\u5f97\u9875\u6846\uff0c\u65e2\u9996\u5148\u5728ZONE_HIGHMEME\u533a\u8bf7\u6c42\u6240\u9700\u5927\u5c0f\u7684\u9875\u6846\uff0c\u5982\u679c\u8be5\u533a\u65e0\u6cd5\u6ee1\u8db3\u8bf7\u6c42\u9875\u6846\u7684\u5927\u5c0f\uff0c\u5219\u518d\u5411ZONE_DMA\u533a\u53d1\u51fa\u8bf7\u6c42\u3002\u5982\u679c\u8be5\u6807\u5fd7\u6ca1\u6709\u88ab\u8bbe\u7f6e\uff0c\u5219\u6309\u7167\u9ed8\u8ba4\u7684ZONE_NORMAL\u548cZONE_DMA\u5185\u5b58\u7ba1\u7406\u533a\u7684\u987a\u5e8f\u83b7\u53d6\u9875\u6846\u3002<\/p>\n
__GFP_ZERO:\u5982\u679c\u8bbe\u7f6e\u4e86\u8be5\u6807\u5fd7\uff0c\u90a3\u4e48\u6240\u7533\u8bf7\u7684\u9875\u6846\u5fc5\u987b\u88ab\u586b\u6ee10\u3002<\/p>\n
API\u5173\u7cfb\u56fe<\/h3>\n
\u672c\u6587\u6240\u4ecb\u7ecd\u7684\u8fd9\u51e0\u4e2aAPI\u672c\u8d28\u4e0a\u90fd\u8c03\u7528\u4e86alloc_pages()\uff0c\u800calloc_pages()\u53c8\u5728\u5176\u5185\u90e8\u8c03\u7528\u4e86alloc_pages_node()\uff0c\u5b83\u4eec\u4e4b\u95f4\u7684\u5173\u7cfb\u5982\u4e0b\u56fe\u6240\u793a\uff1a<\/p>\n
\"\"<\/a><\/p>\n
\u4ece\u56fe\u4e2d\u53ef\u4ee5\u770b\u51fa\uff0calloc_pages_node()\u662f\u6240\u6709\u5206\u914d\u5668API\u7684\u6838\u5fc3\u51fd\u6570\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
\u5728\u7528\u6237\u6001\u4e0b\u7a0b\u5e8f\u4e2d\uff0c\u6211\u4eec\u53ef\u4ee5\u901a\u8fc7malloc()\u52a8\u6001\u7533\u8bf7\u5185\u5b58\u7a7a\u95f4\u3002\u5728\u5185\u6838\u7a7a\u95f4\u4e2d\uff0c\u4e13\u95e8\u6709\u4e00\u4e2a\u5185\u6838\u5b50\u7cfb\u7edf\u5904\u7406\u5bf9\u8fde\u7eed\u9875 […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[266],"tags":[303,268,302],"class_list":["post-3669","post","type-post","status-publish","format-standard","hentry","category-266","tag-alloc","tag-page","tag-302"],"views":7314,"_links":{"self":[{"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/posts\/3669","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/comments?post=3669"}],"version-history":[{"count":0,"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/posts\/3669\/revisions"}],"wp:attachment":[{"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/media?parent=3669"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/categories?post=3669"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/tags?post=3669"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}