{"id":103374,"date":"2026-09-10T11:09:09","date_gmt":"2026-09-10T03:09:09","guid":{"rendered":"https:\/\/www.wsisp.com\/helps\/103374.html"},"modified":"2026-09-10T11:09:09","modified_gmt":"2026-09-10T03:09:09","slug":"mmap%e7%9a%84%e7%9c%9f%e7%9b%b8%ef%bc%9a%e4%b8%8d%e6%8b%b7%e8%b4%9d%ef%bc%8c%e5%8f%aa%e6%98%a0%e5%b0%84","status":"publish","type":"post","link":"https:\/\/www.wsisp.com\/helps\/103374.html","title":{"rendered":"mmap\u7684\u771f\u76f8\uff1a\u4e0d\u62f7\u8d1d\uff0c\u53ea\u6620\u5c04"},"content":{"rendered":"

mmap \u7684\u5e95\u5c42\u771f\u76f8，\u4ee5\u53ca\u5c04\u51fb\u6e38\u620f\u91cc\u7684\u6bcf\u4e00\u6b21\u4ee3\u4ef7<\/h3>\n
\n

\u7b2c 0 \u7ae0：\u5148\u5efa\u7acb\u76f4\u89c9<\/h2>\n

0.1 \u4e00\u4e2a\u6bd4\u55bb：\u540c\u4e00\u672c\u4e66，\u4e24\u4e2a\u95e8\u724c\u53f7<\/h3>\n

\u56fe\u4e66\u9986\u6709\u4e00\u672c\u4e66，\u7f16\u53f7 \u7269\u7406\u4e66\u67b6 P7\u3002<\/p>\n

\u8bfb\u8005 A \u7684\u501f\u4e66\u5355\u4e0a\u5199\u7740："\u7b2c 3 \u53f7\u9605\u89c8\u684c"
\n\u8bfb\u8005 B \u7684\u501f\u4e66\u5355\u4e0a\u5199\u7740："\u7b2c 9 \u53f7\u9605\u89c8\u684c"
\n\u56fe\u4e66\u9986\u7ba1\u7406\u7cfb\u7edf\u91cc\u8bb0\u7740： "\u7269\u7406\u4e66\u67b6 P7"<\/p>\n

\u4e09\u4e2a\u4e0d\u540c\u7684"\u5730\u5740"，\u6307\u5411\u540c\u4e00\u672c\u4e66\u3002<\/p>\n

\u8fd9\u5c31\u662f\u865a\u62df\u5185\u5b58：\u6bcf\u4e2a\u8fdb\u7a0b\u6709\u81ea\u5df1\u7684"\u5730\u5740\u7c3f"（\u9875\u8868），\u4e0d\u540c\u7684\u865a\u62df\u5730\u5740\u53ef\u4ee5\u6620\u5c04\u5230\u540c\u4e00\u4e2a\u7269\u7406\u9875\u3002<\/p>\n

read() \u662f"\u6284\u4e00\u4efd\u7ed9\u4f60"，mmap() \u662f"\u5728\u4f60\u7684\u5730\u5740\u7c3f\u4e0a\u52a0\u4e00\u6761，\u6307\u5411\u539f\u4e66"\u3002<\/p>\n

0.2 \u4e00\u53e5\u8bdd\u6982\u62ec\u672c\u6587\u8981\u8bb2\u7684\u4e1c\u897f<\/h3>\n

mmap \u4e0d\u642c\u6570\u636e，\u5b83\u53ea\u662f\u5f80\u4f60\u7684\u9875\u8868\u91cc\u5199\u4e86\u4e00\u884c，
\n\u8ba9\u67d0\u4e2a\u865a\u62df\u5730\u5740\u7684\u7ffb\u8bd1\u7ed3\u679c，\u843d\u5728 page cache \u5df2\u7ecf\u6301\u6709\u7684\u90a3\u4e2a\u7269\u7406\u9875\u5e27\u4e0a\u3002<\/p>\n

\u542c\u8d77\u6765\u7b80\u5355，\u4f46\u8fd9\u53e5\u8bdd\u91cc\u6bcf\u4e2a\u8bcd\u90fd\u6709\u5751\u3002\u4e0b\u9762\u9010\u5c42\u62c6\u5f00\u3002<\/p>\n

\n

\u7b2c 1 \u7ae0：\u4e09\u4e2a\u5fc5\u987b\u5148\u641e\u6e05\u7684\u6982\u5ff5<\/h2>\n

1.1 \u8fdb\u7a0b\u770b\u5230\u7684\u5730\u5740\u5168\u662f\u5047\u7684<\/h3>\n

byte<\/span>*<\/span> p =<\/span> ..<\/span>.<\/span>;<\/span> \/\/ \u5047\u8bbe\u503c\u662f 0x7f8a3c000000<\/span>
\nDebug.<\/span>Log<\/span>(<\/span>(<\/span>ulong<\/span>)<\/span>p)<\/span>;<\/span> \/\/ \u8fd9\u4e2a\u6570\u5b57\u5728\u7269\u7406\u5185\u5b58\u91cc\u6839\u672c\u4e0d\u5b58\u5728<\/span><\/p>\n

CPU \u6bcf\u6b21\u8bbf\u95ee\u5185\u5b58，\u90fd\u8981\u5148\u8ba9 MMU（\u5185\u5b58\u7ba1\u7406\u5355\u5143） \u628a\u865a\u62df\u5730\u5740\u7ffb\u8bd1\u6210\u7269\u7406\u5730\u5740\u3002\u7ffb\u8bd1\u89c4\u5219\u5b58\u5728\u9875\u8868\u91cc\u3002<\/p>\n

arm64 \u56db\u7ea7\u9875\u8868（4KB \u9875）：<\/p>\n

\u865a\u62df\u5730\u5740 48 \u4f4d：
\n\u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u252c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u252c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u252c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u252c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510
\n\u2502 9 bits \u2502 9 bits \u2502 9 bits \u2502 9 bits \u2502 12 bits \u2502
\n\u2502 PGD \u2502 PUD \u2502 PMD \u2502 PTE \u2502 \u9875\u5185\u504f\u79fb \u2502
\n\u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518
\n \u2502
\n \u2514\u2500\u25b6 PTE \u91cc\u5b58\u7684\u662f\u3010\u7269\u7406\u9875\u5e27\u53f7 PFN\u3011+ \u6743\u9650\u4f4d<\/p>\n

\u7269\u7406\u5730\u5740 = (PFN << 12) | \u9875\u5185\u504f\u79fb<\/p>\n

\u5173\u952e：PTE（\u9875\u8868\u9879）\u91cc\u5b58\u7684\u662f\u7269\u7406\u9875\u5e27\u53f7\u3002\u8c01\u80fd\u6539 PTE，\u8c01\u5c31\u80fd\u51b3\u5b9a"\u8fd9\u4e2a\u865a\u62df\u5730\u5740\u6307\u5411\u54ea\u5757\u7269\u7406\u5185\u5b58"\u3002<\/p>\n

\u5185\u6838\u5c31\u662f\u9760\u6539 PTE \u5b9e\u73b0 mmap \u7684\u3002<\/p>\n

1.2 Page Cache：\u6587\u4ef6\u5728\u5185\u5b58\u91cc\u7684\u90a3\u4efd\u526f\u672c<\/h3>\n

\u4f60\u8bfb\u4e00\u4e2a\u6587\u4ef6，\u6570\u636e\u4e0d\u4f1a\u6bcf\u6b21\u90fd\u4ece\u78c1\u76d8\u6765\u3002\u5185\u6838\u628a\u8bfb\u8fc7\u7684\u9875\u7f13\u5b58\u8d77\u6765：<\/p>\n

\u5185\u6838\u91cc\u7684\u7ed3\u6784：<\/p>\n

struct file \u2192 struct inode \u2192 struct address_space
\n \u2502
\n \u2514\u2500 i_pages（XArray）
\n \u7d22\u5f15 = \u6587\u4ef6\u5185\u9875\u53f7 (pgoff)
\n \u503c = struct page*<\/p>\n

pgoff 0 \u2192 page(PFN=0x12345)
\n pgoff 1 \u2192 page(PFN=0x12346)
\n pgoff 2 \u2192 （\u4e0d\u5728，\u9700\u8981\u8bfb\u76d8）
\n pgoff 3 \u2192 page(PFN=0x1AF20)<\/p>\n

Page Cache \u7684\u4e09\u4e2a\u6027\u8d28：<\/p>\n\n\u6027\u8d28\u542b\u4e49<\/tr>\n\n\n\n\n
\u5168\u5c40\u5171\u4eab<\/td>\n\u4e00\u4e2a\u6587\u4ef6\u7684 page cache \u53ea\u6709\u4e00\u4efd，\u6240\u6709\u8fdb\u7a0b\u5171\u7528<\/td>\n<\/tr>\n
\u6309\u9875\u7ba1\u7406<\/td>\n\u5355\u4f4d\u662f 4KB（Android 15+ arm64 \u53ef\u80fd\u662f 16KB）<\/td>\n<\/tr>\n
\u53ef\u56de\u6536<\/td>\n\u5185\u5b58\u7d27\u5f20\u65f6，\u5e72\u51c0\u9875\u76f4\u63a5\u4e22，\u810f\u9875\u5148\u5199\u56de\u518d\u4e22<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

1.3 \u4e3a\u4ec0\u4e48 read() \u5fc5\u987b\u62f7\u8d1d<\/h3>\n

char<\/span> buf[<\/span>4096<\/span>]<\/span>;<\/span>
\nread<\/span>(<\/span>fd,<\/span> buf,<\/span> 4096<\/span>)<\/span>;<\/span><\/p>\n

buf \u662f\u4f60\u7684\u7528\u6237\u6001\u6808\/\u5806\u5185\u5b58，\u5b83\u5bf9\u5e94\u7684\u7269\u7406\u9875\u548c page cache \u7684\u7269\u7406\u9875\u662f\u4e24\u5757\u4e0d\u540c\u7684\u7269\u7406\u5185\u5b58\u3002<\/p>\n

\u7269\u7406\u5185\u5b58
\n\u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510
\n\u2502 PFN=0x12345 \u2502 \u2190 page cache \u7684\u9875（\u5185\u6838\u6301\u6709）
\n\u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518
\n \u2502 memcpy_to_user() \u2605 \u4e00\u6b21\u771f\u5b9e\u7684 CPU \u62f7\u8d1d
\n \u25bc
\n\u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510
\n\u2502 PFN=0x9ABCD \u2502 \u2190 \u4f60\u7684 buf \u5bf9\u5e94\u7684\u9875
\n\u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518<\/p>\n

\u5185\u6838\u4e0d\u80fd\u628a buf \u7684 PTE \u76f4\u63a5\u6539\u6210\u6307\u5411 page cache，\u56e0\u4e3a：<\/p>\n

    \n
  • buf \u662f\u4f60\u5148\u5206\u914d\u7684，\u5b83\u5df2\u7ecf\u6709\u81ea\u5df1\u7684\u7269\u7406\u9875<\/li>\n
  • \u4f60\u53ef\u80fd\u968f\u610f\u6539 buf，\u6539\u4e86\u4e0d\u8be5\u5f71\u54cd\u6587\u4ef6\u5185\u5bb9<\/li>\n
  • buf \u53ef\u80fd\u4e0d\u662f\u9875\u5bf9\u9f50\u7684（char buf[100]）<\/li>\n<\/ul>\n

    \u6240\u4ee5 read() \u5fc5\u987b\u62f7\u8d1d\u3002\u800c mmap \u4ece\u4e00\u5f00\u59cb\u5c31\u4e0d\u7ed9\u4f60\u5206\u914d\u7269\u7406\u9875，\u7b49\u4f60\u8bbf\u95ee\u65f6\u624d\u51b3\u5b9a\u6307\u5411\u54ea\u3002<\/p>\n

    \n

    \u7b2c 2 \u7ae0：mmap \u5230\u5e95\u505a\u4e86\u4ec0\u4e48（\u51e0\u4e4e\u4ec0\u4e48\u90fd\u6ca1\u505a）<\/h2>\n

    2.1 mmap \u8fd4\u56de\u65f6，\u9875\u8868\u662f\u7a7a\u7684<\/h3>\n

    void<\/span>*<\/span> p =<\/span> mmap<\/span>(<\/span>NULL<\/span>,<\/span> 8<\/span>*<\/span>1024<\/span>*<\/span>1024<\/span>,<\/span> PROT_READ,<\/span> MAP_SHARED,<\/span> fd,<\/span> 0<\/span>)<\/span>;<\/span>
    \n\/\/ \u6620\u5c04 8MB\u3002\u6b64\u65f6：<\/span>
    \n\/\/ \u2705 \u5df2\u5efa\u7acb\u4e00\u4e2a vm_area_struct（VMA）<\/span>
    \n\/\/ \u2705 \u5df2\u5212\u51fa\u4e00\u6bb5\u865a\u62df\u5730\u5740\u8303\u56f4<\/span>
    \n\/\/ \u274c \u9875\u8868\u91cc 0 \u6761\u6709\u6548 PTE<\/span>
    \n\/\/ \u274c \u78c1\u76d8 IO：0 \u6b21<\/span>
    \n\/\/ \u274c \u7269\u7406\u5185\u5b58\u5206\u914d：0 \u5b57\u8282<\/span><\/p>\n

    VMA \u662f\u4ec0\u4e48：\u5185\u6838\u91cc\u63cf\u8ff0"\u8fd9\u6bb5\u865a\u62df\u5730\u5740\u662f\u5e72\u4ec0\u4e48\u7528\u7684"\u7684\u5143\u6570\u636e\u3002<\/p>\n

    struct<\/span> vm_area_struct<\/span> {<\/span>
    \n unsigned<\/span> long<\/span> vm_start,<\/span> vm_end;<\/span> \/\/ \u865a\u62df\u5730\u5740\u8303\u56f4<\/span>
    \n struct<\/span> file<\/span> *<\/span>vm_file;<\/span> \/\/ \u2605 \u5173\u8054\u54ea\u4e2a\u6587\u4ef6<\/span>
    \n unsigned<\/span> long<\/span> vm_pgoff;<\/span> \/\/ \u2605 \u4ece\u6587\u4ef6\u7b2c\u51e0\u9875\u5f00\u59cb<\/span>
    \n unsigned<\/span> long<\/span> vm_flags;<\/span> \/\/ VM_SHARED \/ VM_READ \/ VM_WRITE<\/span>
    \n const<\/span> struct<\/span> vm_operations_struct<\/span> *<\/span>vm_ops;<\/span> \/\/ \u2605 \u7f3a\u9875\u65f6\u8c03\u8c01<\/span>
    \n}<\/span>;<\/span><\/p>\n

    mmap \u7684\u5168\u90e8\u5de5\u4f5c = \u9020\u4e00\u4e2a VMA，\u63d2\u8fdb\u7ea2\u9ed1\u6811，\u8fd4\u56de\u5730\u5740\u3002<\/p>\n

    \u8017\u65f6\u7ea6 1~10 \u5fae\u79d2，\u548c\u6587\u4ef6\u5927\u5c0f\u65e0\u5173\u3002\u6620\u5c04 8MB \u548c\u6620\u5c04 8GB \u4e00\u6837\u5feb\u3002<\/p>\n

    2.2 \u7b2c\u4e00\u6b21\u8bbf\u95ee：\u7f3a\u9875\u5f02\u5e38\u7684\u5b8c\u6574\u6d41\u7a0b<\/h3>\n

    char<\/span> c =<\/span> (<\/span>(<\/span>char<\/span>*<\/span>)<\/span>p)<\/span>[<\/span>0<\/span>]<\/span>;<\/span> \/\/ \u5c31\u8fd9\u4e00\u884c，\u89e6\u53d1\u4e0b\u9762\u5168\u90e8\u6d41\u7a0b<\/span><\/p>\n

    \u2460 CPU \u53d1\u51fa\u865a\u62df\u5730\u5740 \u2192 MMU \u67e5\u9875\u8868
    \n PTE \u65e0\u6548（present \u4f4d\u4e3a 0）
    \n \u2193
    \n\u2461 CPU \u629b\u51fa\u540c\u6b65\u5f02\u5e38（arm64: Data Abort）
    \n \u5207\u5230\u5185\u6838\u6001，\u8fdb\u5165 do_page_fault()
    \n \u2193
    \n\u2462 \u5728\u5f53\u524d\u8fdb\u7a0b\u7684 VMA \u7ea2\u9ed1\u6811\u91cc\u627e："\u8fd9\u4e2a\u5730\u5740\u5c5e\u4e8e\u54ea\u4e2a VMA？"
    \n \u627e\u4e0d\u5230 \u2192 SIGSEGV（\u6bb5\u9519\u8bef）
    \n \u627e\u5230\u4e86 \u2192 \u68c0\u67e5\u6743\u9650（\u5199\u53ea\u8bfb\u533a \u2192 SIGSEGV）
    \n \u2193
    \n\u2463 handle_mm_fault() \u2192 \u5224\u65ad VMA \u7c7b\u578b
    \n vm_file != NULL \u2192 \u6587\u4ef6\u6620\u5c04，\u8c03 vma->vm_ops->fault
    \n \u5bf9\u666e\u901a\u6587\u4ef6\u5c31\u662f filemap_fault()
    \n \u2193
    \n\u2464 filemap_fault()：\u7b97\u51fa\u6587\u4ef6\u5185\u9875\u53f7
    \n pgoff = vm_pgoff + (addr – vm_start) \/ PAGE_SIZE<\/p>\n

    \u5728 address_space \u7684 XArray \u91cc\u67e5 pgoff：
    \n \u251c\u2500 \u547d\u4e2d \u2192 \u2605 Minor Fault，\u8df3\u5230 \u2466
    \n \u2514\u2500 \u672a\u547d\u4e2d \u2192 \u2605 Major Fault，\u8d70 \u2465
    \n \u2193
    \n\u2465 \u3010Major Fault\u3011
    \n a. \u5206\u914d\u4e00\u4e2a\u7269\u7406\u9875
    \n b. \u6302\u8fdb page cache（XArray[pgoff] = page）
    \n c. \u63d0\u4ea4\u8bfb IO，\u628a\u8fd9\u4e00\u9875\u586b\u4e0a
    \n d. \u2605 \u5f53\u524d\u7ebf\u7a0b\u7761\u7720\u7b49 IO \u5b8c\u6210（\u8fd9\u5c31\u662f\u5361\u987f\u6765\u6e90）
    \n \u2193
    \n\u2466 \u5efa\u7acb PTE
    \n pfn = page_to_pfn(page); \/\/ \u2605 page cache \u90a3\u4e00\u9875\u7684\u7269\u7406\u9875\u5e27\u53f7
    \n set_pte_at(mm, addr, ptep, mk_pte(page, prot));
    \n page->_mapcount++; \/\/ \u8bb0\u5f55"\u591a\u4e86\u4e00\u4e2a\u8fdb\u7a0b\u6620\u5c04\u6211"
    \n \u2193
    \n\u2467 \u4ece\u5f02\u5e38\u8fd4\u56de，CPU \u91cd\u65b0\u6267\u884c\u90a3\u6761 load \u6307\u4ee4
    \n \u8fd9\u6b21 MMU \u7ffb\u8bd1\u6210\u529f，\u8bfb\u5230\u6570\u636e<\/p>\n

    2.3 \u5173\u952e\u7684\u4e00\u53e5：PTE \u6307\u5411\u7684\u5c31\u662f page cache \u7684\u9875<\/h3>\n

    \u7b2c \u2466 \u6b65\u662f\u672c\u6587\u6807\u9898\u7684\u7b54\u6848：<\/p>\n

    pfn =<\/span> page_to_pfn<\/span>(<\/span>page)<\/span>;<\/span><\/p>\n

    page \u662f\u4ece page cache \u7684 XArray \u91cc\u62ff\u51fa\u6765\u7684 struct page*\u3002\u5b83\u7684\u7269\u7406\u9875\u5e27\u53f7\u88ab\u76f4\u63a5\u5199\u8fdb\u4e86\u4f60\u7684 PTE\u3002<\/p>\n

    \u4ece\u8fd9\u4e00\u523b\u8d77：<\/p>\n

    \u4f60\u7684\u865a\u62df\u5730\u5740 p+0
    \n \u2502 MMU \u7ffb\u8bd1
    \n \u25bc
    \n \u7269\u7406\u9875 PFN=0x12345
    \n \u25b2
    \n \u2502 page cache \u7684 XArray[0] \u4e5f\u6307\u5411\u5b83
    \n \u5185\u6838 address_space<\/p>\n

    \u2192 \u540c\u4e00\u5757\u7269\u7406\u5185\u5b58，\u4e24\u4e2a"\u540d\u5b57"
    \n\u2192 \u4f60\u8bfb\u5b83，\u5c31\u662f\u8bfb page cache
    \n\u2192 \u4f60\u5199\u5b83（MAP_SHARED），\u5c31\u662f\u6539 page cache<\/p>\n

    2.4 \u4e00\u4e2a\u91cd\u8981\u4f18\u5316：Fault-Around<\/h3>\n

    \u5982\u679c\u6bcf\u8bbf\u95ee 4KB \u5c31\u5f02\u5e38\u4e00\u6b21，8MB \u6587\u4ef6\u8981 2048 \u6b21\u5f02\u5e38，\u592a\u6162\u3002<\/p>\n

    \u5185\u6838\u505a\u4e86 fault-around：\u4e00\u6b21 minor fault，\u987a\u4fbf\u628a\u5468\u56f4\u5df2\u5728 page cache \u7684\u9875\u4e00\u8d77\u5efa PTE\u3002<\/p>\n

    \/\/ mm\/memory.c<\/span>
    \nstatic<\/span> unsigned<\/span> long<\/span> fault_around_bytes __read_mostly =<\/span> 65536<\/span>;<\/span> \/\/ 16 \u9875<\/span><\/p>\n

    do_fault_around<\/span>(<\/span>)<\/span>:<\/span>
    \n \u4ee5\u51fa\u9519\u5730\u5740\u4e3a\u4e2d\u5fc3，\u5411\u524d\u540e\u6269\u5c55\u5230 64<\/span>KB \u8fb9\u754c
    \n \u5bf9\u6bcf\u4e00\u9875：\u5982\u679c\u5728 page cache \u91cc \u2192 \u4e00\u8d77\u5efa PTE<\/p>\n

    \u6548\u679c：\u987a\u5e8f\u8bbf\u95ee\u4e00\u4e2a\u5df2\u7f13\u5b58\u7684\u6587\u4ef6，\u7f3a\u9875\u6b21\u6570\u964d\u5230 1\/16\u3002<\/p>\n

    \u8fd9\u89e3\u91ca\u4e86\u4e00\u4e2a\u73b0\u8c61：\u9884\u70ed\u8fc7\u7684 bundle，\u52a0\u8f7d\u65f6\u51e0\u4e4e\u770b\u4e0d\u5230 fault；\u6ca1\u9884\u70ed\u7684，fault \u6570\u91cf\u60ca\u4eba\u3002\u56e0\u4e3a fault-around \u53ea\u6620\u5c04\u5df2\u5728\u7f13\u5b58\u7684\u9875，\u7f13\u5b58\u91cc\u6ca1\u6709\u7684\u8bdd\u5b83\u5e2e\u4e0d\u4e0a\u5fd9\u3002<\/p>\n

    \n

    \u7b2c 3 \u7ae0：\u5171\u4eab vs \u79c1\u6709，\u4ee5\u53ca\u5199\u5165\u7684\u4ee3\u4ef7<\/h2>\n

    3.1 MAP_SHARED：\u771f\u6b63\u7684\u5171\u4eab<\/h3>\n

    mmap<\/span>(<\/span>.<\/span>.<\/span>.<\/span>,<\/span> PROT_READ|<\/span>PROT_WRITE,<\/span> MAP_SHARED,<\/span> fd,<\/span> 0<\/span>)<\/span>;<\/span><\/p>\n

    \u8fdb\u7a0b A \u7684 PTE \u2500\u2500\u2510
    \n \u251c\u2500\u2500\u25b6 \u7269\u7406\u9875 PFN=0x12345 \u25c0\u2500\u2500 page cache
    \n\u8fdb\u7a0b B \u7684 PTE \u2500\u2500\u2518<\/p>\n

    \u5199\u5165 \u2192 \u76f4\u63a5\u6539\u8fd9\u5757\u7269\u7406\u5185\u5b58
    \n \u2192 PTE \u7684 dirty \u4f4d\u7f6e 1
    \n \u2192 \u5185\u6838\u6807\u8bb0 page \u4e3a PageDirty
    \n \u2192 writeback \u7ebf\u7a0b\u7a0d\u540e\u5199\u56de\u6587\u4ef6<\/p>\n

    \u4e09\u4e2a\u63a8\u8bba（\u90fd\u5f88\u91cd\u8981）：<\/p>\n

  • A \u5199\u7684\u5185\u5bb9 B \u7acb\u523b\u770b\u5f97\u5230（\u540c\u4e00\u5757\u7269\u7406\u5185\u5b58，\u65e0\u9700\u4efb\u4f55\u540c\u6b65\u673a\u5236）<\/li>\n
  • \u5185\u5bb9\u4f1a\u843d\u5230\u6587\u4ef6\u91cc（\u8fd9\u662f\u6301\u4e45\u5316\u7684\u57fa\u7840）<\/li>\n
  • \u8fdb\u7a0b\u88ab SIGKILL \u4e5f\u4e0d\u4e22（\u810f\u9875\u5728\u5185\u6838，\u8fdb\u7a0b\u6b7b\u4e86\u5185\u6838\u7167\u6837\u5199\u56de）<\/li>\n

    3.2 MAP_PRIVATE：\u5199\u65f6\u590d\u5236\u7684\u9677\u9631<\/h3>\n

    mmap<\/span>(<\/span>.<\/span>.<\/span>.<\/span>,<\/span> PROT_READ|<\/span>PROT_WRITE,<\/span> MAP_PRIVATE,<\/span> fd,<\/span> 0<\/span>)<\/span>;<\/span><\/p>\n

    \u3010\u8bfb\u9636\u6bb5\u3011\u548c SHARED \u4e00\u6837，PTE \u6307\u5411 page cache，\u4f46\u6807\u8bb0\u4e3a\u53ea\u8bfb<\/p>\n

    \u3010\u7b2c\u4e00\u6b21\u5199\u3011
    \n \u2460 \u5199\u53ea\u8bfb PTE \u2192 \u89e6\u53d1\u5199\u4fdd\u62a4\u7f3a\u9875
    \n \u2461 do_wp_page()：\u5206\u914d\u4e00\u4e2a\u65b0\u7684\u533f\u540d\u9875
    \n \u2462 \u628a page cache \u90a3\u9875\u7684\u5185\u5bb9 memcpy \u8fc7\u53bb \u2605 \u4e00\u6b21\u771f\u5b9e\u62f7\u8d1d
    \n \u2463 PTE \u6539\u6307\u5411\u65b0\u9875，\u6807\u8bb0\u53ef\u5199
    \n \u2464 \u4ece\u6b64\u8fd9\u4e00\u9875\u548c\u6587\u4ef6\u3001\u548c page cache \u5b8c\u5168\u8131\u94a9<\/p>\n

    \u5c04\u51fb\u6e38\u620f\u91cc\u7684\u771f\u5b9e\u4e8b\u6545：<\/p>\n

    \/\/ \u67d0\u9879\u76ee\u7528 MAP_PRIVATE \u6620\u5c04\u4e86 200MB \u7684\u5730\u56fe\u6570\u636e<\/span>
    \n\/\/ \u7136\u540e\u5728\u52a0\u8f7d\u65f6\u505a\u4e86"\u539f\u5730\u4fee\u6b63\u5750\u6807"<\/span>
    \nfor<\/span> (<\/span>int<\/span><\/span> i =<\/span> 0<\/span>;<\/span> i <<\/span> vertexCount;<\/span> i++<\/span>)<\/span>
    \n vertices[<\/span>i]<\/span>.<\/span>y +=<\/span> terrainOffset;<\/span> \/\/ \u274c \u6bcf\u5199\u4e00\u9875\u89e6\u53d1 COW<\/span><\/p>\n

    \/\/ \u7ed3\u679c：<\/span>
    \n\/\/ \u6620\u5c04\u65f6 PSS \u589e\u91cf \u2248 0<\/span>
    \n\/\/ \u904d\u5386\u5b8c\u6210\u540e PSS \u589e\u91cf = 200 MB（\u5168\u90e8 COW \u6210\u533f\u540d\u9875）<\/span>
    \n\/\/ \u800c\u4e14\u533f\u540d\u9875\u4e0d\u80fd\u88ab\u76f4\u63a5\u56de\u6536，\u53ea\u80fd swap（Android \u4e0a\u6ca1 swap \u2192 \u76f4\u63a5 OOM）<\/span><\/p>\n\nMAP_SHAREDMAP_PRIVATE<\/tr>\n\n\n\n\n\n\n
    \u8bfb<\/td>\n\u6307\u5411 page cache<\/td>\n\u6307\u5411 page cache<\/td>\n<\/tr>\n
    \u5199<\/td>\n\u6539 page cache<\/td>\nCOW \u51fa\u533f\u540d\u9875<\/td>\n<\/tr>\n
    \u5185\u5b58\u5f52\u7c7b<\/td>\nfile-backed，\u53ef\u76f4\u63a5\u56de\u6536<\/td>\nanon，\u53ea\u80fd swap<\/td>\n<\/tr>\n
    \u4f1a\u5199\u56de\u6587\u4ef6<\/td>\n\u2705<\/td>\n\u274c<\/td>\n<\/tr>\n
    \u9002\u7528<\/td>\n\u8bfb\u5199\u5171\u4eab\u6570\u636e\u3001\u65e5\u5fd7\u3001\u5f55\u50cf<\/td>\n\u53ea\u8bfb\u4e3a\u4e3b\u7684\u8d44\u6e90<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

    📌 \u89c4\u5219：\u53ea\u8bfb\u8d44\u6e90\u7528 MAP_PRIVATE \u4e14\u7edd\u4e0d\u5199\u5165；\u8981\u5199\u5c31\u7528 MAP_SHARED\u3002 \u6df7\u7740\u6765\u5fc5\u7136\u51fa\u4e8b\u3002<\/p>\n

    \n

    \u7b2c 4 \u7ae0：\u5185\u5b58\u538b\u529b\u4e0b\u4f1a\u53d1\u751f\u4ec0\u4e48（\u6700\u5bb9\u6613\u88ab\u5ffd\u7565）<\/h2>\n

    4.1 mmap \u7684\u9875\u4e5f\u4f1a\u88ab\u56de\u6536<\/h3>\n

    \u5f88\u591a\u4eba\u4ee5\u4e3a mmap \u4e4b\u540e\u9875\u5c31"\u9489\u4f4f"\u4e86\u3002\u4e0d\u662f\u7684\u3002<\/p>\n

    \u5185\u6838 LRU \u94fe\u8868：
    \n \u251c\u2500 active_file \u2190 \u6700\u8fd1\u8bbf\u95ee\u8fc7\u7684\u6587\u4ef6\u9875
    \n \u251c\u2500 inactive_file \u2190 \u51b7\u7684\u6587\u4ef6\u9875
    \n \u251c\u2500 active_anon
    \n \u2514\u2500 inactive_anon<\/p>\n

    \u5185\u5b58\u4e0d\u8db3\u65f6，kswapd \/ direct reclaim \u4ece inactive \u5c3e\u90e8\u5f00\u5200：<\/p>\n

    \u5e72\u51c0\u7684\u6587\u4ef6\u9875（clean file page）
    \n \u2192 \u2605 \u76f4\u63a5 free，\u96f6\u6210\u672c（\u5185\u5bb9\u548c\u78c1\u76d8\u4e00\u81f4）
    \n \u2192 \u6e05\u6389\u6240\u6709\u6307\u5411\u5b83\u7684 PTE<\/p>\n

    \u810f\u7684\u6587\u4ef6\u9875（dirty）
    \n \u2192 \u5148\u5199\u56de\u6587\u4ef6，\u518d free<\/p>\n

    \u533f\u540d\u9875（anon）
    \n \u2192 \u9700\u8981 swap；Android \u901a\u5e38\u65e0 swap \u5206\u533a
    \n \u2192 \u53ea\u80fd\u9760 zram \u538b\u7f29，\u6216\u8005\u2026\u2026\u6740\u8fdb\u7a0b<\/p>\n

    \u63a8\u8bba 1（\u597d\u6d88\u606f）：mmap \u7684\u53ea\u8bfb\u8d44\u6e90\u662f\u7cfb\u7edf\u773c\u91cc\u6700\u4fbf\u5b9c\u7684\u5185\u5b58\u3002<\/p>\n

    \u63a8\u8bba 2（\u574f\u6d88\u606f）：\u88ab\u56de\u6536\u7684\u9875\u518d\u8bbf\u95ee，\u53c8\u662f\u4e00\u6b21 major fault\u3002<\/p>\n

    4.2 \u8fd9\u5c31\u662f"\u5185\u5b58\u538b\u529b\u4e0b\u7684\u6296\u52a8"<\/h3>\n

    \u5c04\u51fb\u6e38\u620f\u5728 4GB \u5185\u5b58\u673a\u5668\u4e0a，\u7528\u6237\u540e\u53f0\u8fd8\u5f00\u7740\u5fae\u4fe1：<\/p>\n

    T0：\u52a0\u8f7d\u5b8c\u5730\u56fe，8MB bundle \u7684\u9875\u5168\u5728 page cache
    \n T1：\u73a9\u5bb6\u5207\u540e\u53f0\u770b\u4e86\u773c\u5fae\u4fe1
    \n T2：\u5fae\u4fe1\u8981\u5185\u5b58 \u2192 kswapd \u56de\u6536\u5e72\u51c0\u6587\u4ef6\u9875
    \n \u2192 \u4f60\u7684 bundle \u9875\u88ab\u56de\u6536（\u56e0\u4e3a\u5b83\u4eec\u6700"\u4fbf\u5b9c"）
    \n T3：\u73a9\u5bb6\u5207\u56de\u6765 \u2192 \u91cd\u65b0\u8bbf\u95ee\u6a21\u578b\u6570\u636e
    \n \u2192 \u2605 major fault \u98ce\u66b4，\u5361 200ms<\/p>\n

    \u8fd9\u5c31\u662f"\u5207\u540e\u53f0\u518d\u56de\u6765\u4f1a\u5361"\u7684\u5e95\u5c42\u539f\u56e0\u4e4b\u4e00\u3002<\/p>\n

    4.3 mlock：\u9489\u4f4f\u9875\u7684\u4ee3\u4ef7<\/h3>\n

    mlock<\/span>(<\/span>addr,<\/span> len)<\/span>;<\/span> \/\/ \u5f3a\u5236\u8fd9\u6bb5\u9875\u5e38\u9a7b，\u4e0d\u8bb8\u56de\u6536<\/span><\/p>\n

    \u80fd\u89e3\u51b3\u6296\u52a8，\u4f46：<\/p>\n

    \u2460 RLIMIT_MEMLOCK \u9650\u5236（Android \u4e0a\u901a\u5e38\u5f88\u5c0f，\u9700\u8981\u7279\u6743）
    \n\u2461 \u88ab mlock \u7684\u9875\u5bf9 LMK \u6765\u8bf4\u662f"\u4e0d\u53ef\u56de\u6536\u5185\u5b58"
    \n \u2192 \u4f60\u7684 oom_score \u53d8\u9ad8
    \n \u2192 \u2605 \u7cfb\u7edf\u4e0d\u56de\u6536\u4f60\u7684\u9875，\u6539\u4e3a\u76f4\u63a5\u6740\u4f60\u7684\u8fdb\u7a0b
    \n\u2462 \u76f8\u5f53\u4e8e\u628a"\u5c40\u90e8\u5361\u987f"\u6362\u6210"\u6574\u4f53\u95ea\u9000"<\/p>\n

    \u66f4\u5b9e\u7528\u7684\u66ff\u4ee3\u65b9\u6848：<\/p>\n

    \/\/ \u6e29\u548c\u7684\u5efa\u8bae：\u544a\u8bc9\u5185\u6838"\u8fd9\u6bb5\u6211\u5f88\u5feb\u8981\u7528，\u5c3d\u91cf\u7559\u7740"<\/span>
    \nmadvise<\/span>(<\/span>addr,<\/span> len,<\/span> MADV_WILLNEED)<\/span>;<\/span><\/p>\n

    \/\/ \u544a\u8bc9\u5185\u6838"\u8fd9\u6bb5\u6211\u968f\u673a\u8bbf\u95ee，\u522b\u505a\u987a\u5e8f\u9884\u8bfb"<\/span>
    \nmadvise<\/span>(<\/span>addr,<\/span> len,<\/span> MADV_RANDOM)<\/span>;<\/span><\/p>\n

    \/\/ \u544a\u8bc9\u5185\u6838"\u8fd9\u6bb5\u6211\u4e0d\u9700\u8981\u4e86，\u968f\u4fbf\u56de\u6536"（\u5173\u5361\u5207\u6362\u65f6\u7528）<\/span>
    \nmadvise<\/span>(<\/span>addr,<\/span> len,<\/span> MADV_DONTNEED)<\/span>;<\/span> \/\/ \u26a0\ufe0f MAP_PRIVATE \u4e0b\u4f1a\u4e22\u5f03 COW \u7684\u4fee\u6539！<\/span><\/p>\n

    4.4 PSS \u662f\u600e\u4e48\u7b97\u7684<\/h3>\n

    Android \u7684 dumpsys meminfo \u663e\u793a\u7684 PSS（Proportional Set Size）：<\/p>\n

    \u4e00\u4e2a\u7269\u7406\u9875\u88ab N \u4e2a\u8fdb\u7a0b\u6620\u5c04 \u2192 \u6bcf\u4e2a\u8fdb\u7a0b\u7b97 1\/N \u9875<\/p>\n

    \u4f8b：libunity.so \u7684 .text \u6bb5\u88ab 3 \u4e2a\u8fdb\u7a0b\u6620\u5c04
    \n \u2192 \u6bcf\u4e2a\u8fdb\u7a0b\u7684 PSS \u53ea\u8ba1\u5165 1\/3<\/p>\n

    mmap \u4e00\u4e2a\u53ea\u6709\u81ea\u5df1\u5728\u7528\u7684 bundle
    \n \u2192 mapcount = 1 \u2192 PSS \u5168\u989d\u8ba1\u5165<\/p>\n

    \u2605 \u4f46\u53ea\u6709\u3010\u5b9e\u9645 fault \u8fdb\u6765\u7684\u9875\u3011\u624d\u8ba1\u5165
    \n \u6620\u5c04\u4e86 8MB \u4f46\u53ea\u8bbf\u95ee\u4e86 1MB \u2192 PSS \u53ea\u589e 1MB<\/p>\n

    \u8fd9\u5c31\u662f LoadFromFile \u6bd4 LoadFromMemory \u5185\u5b58\u4f4e 10 \u500d\u7684\u771f\u6b63\u539f\u56e0：\u4e0d\u662f"\u66f4\u7701"，\u800c\u662f\u5f88\u591a\u9875\u4ece\u6765\u6ca1\u88ab\u8bbf\u95ee\u8fc7，\u6240\u4ee5\u4ece\u6765\u6ca1\u88ab fault \u8fdb\u6765\u3002<\/p>\n

    \n

    \u7b2c 5 \u7ae0：Android \u7684\u7279\u6b8a\u60c5\u51b5<\/h2>\n

    5.1 APK \u5185 mmap \u4e0e\u9875\u5bf9\u9f50<\/h3>\n

    Unity \u5728 Android \u4e0a\u53ef\u4ee5\u76f4\u63a5 mmap APK \u91cc\u7684 bundle：<\/p>\n

    var<\/span><\/span> ab =<\/span> AssetBundle.<\/span>LoadFromFile<\/span>(<\/span>
    \n Path.<\/span>Combine<\/span>(<\/span>Application.<\/span>streamingAssetsPath,<\/span> "aa\/Android\/base.bundle"<\/span>)<\/span>)<\/span>;<\/span><\/p>\n

    \u80fd\u6210\u7acb\u7684\u4e24\u4e2a\u786c\u6761\u4ef6：<\/p>\n

    \u2460 \u8be5 ZIP \u6761\u76ee\u5fc5\u987b\u662f STORED（\u4e0d\u538b\u7f29）
    \n \u2192 \u53ea\u6709\u539f\u6837\u5b58\u653e，\u6587\u4ef6\u5185\u504f\u79fb\u624d\u5bf9\u5e94\u8fde\u7eed\u7684\u5b57\u8282\u6d41
    \n \u2192 Deflate \u538b\u7f29\u7684\u6761\u76ee\u65e0\u6cd5 mmap，\u5fc5\u987b\u5168\u91cf\u89e3\u538b<\/p>\n

    \u2461 mmap \u7684 offset \u5fc5\u987b\u9875\u5bf9\u9f50
    \n \u2192 mmap(fd, offset) \u8981\u6c42 offset % PAGE_SIZE == 0
    \n \u2192 \u6240\u4ee5 zipalign \u5b58\u5728\u7684\u610f\u4e49\u5c31\u662f\u8ba9\u6761\u76ee\u8d77\u59cb\u4f4d\u7f6e\u5bf9\u9f50<\/p>\n

    # \u9a8c\u8bc1<\/span>
    \nadb shell pm path com.xxx.game
    \nadb pull \/data\/app\/..<\/span>.\/base.apk
    \nunzip<\/span> -v<\/span> base.apk |<\/span> grep<\/span> -E<\/span> "bundle|\\\\.so"<\/span><\/p>\n

    8452096 Stored 8452096 0% assets\/aa\/Android\/base.bundle \u2190 \u2705 \u53ef mmap
    \n 24336384 Stored 24336384 0% lib\/arm64-v8a\/libil2cpp.so \u2190 \u2705 \u53ef mmap
    \n 4231680 Defl:N 1892304 55% assets\/config\/weapons.json \u2190 \u274c \u9700\u89e3\u538b<\/p>\n

    Android 15 \u8d77 arm64 \u652f\u6301 16KB \u9875，\u5bf9\u9f50\u8981\u6c42\u53d8\u6210 16KB：<\/p>\n

    android {
    \n \/\/ \u4fdd\u8bc1 bundle \u4e0d\u88ab\u538b\u7f29
    \n aaptOptions { noCompress '.bundle', '.unity3d', '.resS', '.resource' }
    \n \/\/ \u4fdd\u8bc1 so 16KB \u5bf9\u9f50（NDK r27+ \/ AGP 8.5+）
    \n packagingOptions { jniLibs { useLegacyPackaging false } }
    \n}<\/p>\n

    5.2 \u5916\u90e8\u5b58\u50a8\u7684 FUSE \u60e9\u7f5a<\/h3>\n

    \/data\/data\/\u5305\u540d\/files\/x.bundle
    \n \u2192 ext4\/f2fs，mmap \u7684 major fault \u8d70\u6807\u51c6\u5757\u8bbe\u5907\u8def\u5f84
    \n \u2192 \u4e00\u6b21 fault \u2248 100 \u03bcs<\/p>\n

    \/storage\/emulated\/0\/Android\/data\/\u5305\u540d\/files\/x.bundle
    \n \u2192 \u2605 FUSE \u865a\u62df\u6587\u4ef6\u7cfb\u7edf，\u8f6c\u53d1\u5230 \/data\/media\/0
    \n \u2192 major fault \u9700\u8981 upcall \u5230\u7528\u6237\u6001 daemon \u518d\u56de\u6765
    \n \u2192 \u4e00\u6b21 fault \u2248 200~500 \u03bcs<\/p>\n

    \u7ed3\u8bba：mmap \u5bc6\u96c6\u8bbf\u95ee\u7684\u6587\u4ef6\u5fc5\u987b\u653e\u5185\u90e8\u5b58\u50a8\u3002 \u5916\u90e8\u5b58\u50a8\u53ea\u653e\u4f4e\u9891\u5927\u6587\u4ef6\u3002<\/p>\n

    5.3 \u533f\u540d\u5171\u4eab\u5185\u5b58：ashmem \/ memfd<\/h3>\n

    \u8de8\u8fdb\u7a0b\u5171\u4eab\u7528\u4e0d\u4e86\u666e\u901a\u6587\u4ef6，\u7528\u533f\u540d\u5171\u4eab\u5185\u5b58：<\/p>\n

    #<\/span>include<\/span> <android\/sharedmem.h><\/span><\/span><\/p>\n

    \/\/ \u4e3b\u8fdb\u7a0b<\/span>
    \nint<\/span> fd =<\/span> ASharedMemory_create<\/span>(<\/span>"replay_ring"<\/span>,<\/span> 8<\/span>*<\/span>1024<\/span>*<\/span>1024<\/span>)<\/span>;<\/span>
    \nvoid<\/span>*<\/span> base =<\/span> mmap<\/span>(<\/span>NULL<\/span>,<\/span> size,<\/span> PROT_READ|<\/span>PROT_WRITE,<\/span> MAP_SHARED,<\/span> fd,<\/span> 0<\/span>)<\/span>;<\/span>
    \n\/\/ \u901a\u8fc7 Binder \u628a fd \u4f20\u7ed9\u5f55\u5236\u8fdb\u7a0b<\/span><\/p>\n

    \/\/ \u5f55\u5236\u8fdb\u7a0b\u6536\u5230 fd \u540e<\/span>
    \nvoid<\/span>*<\/span> base2 =<\/span> mmap<\/span>(<\/span>NULL<\/span>,<\/span> size,<\/span> PROT_READ,<\/span> MAP_SHARED,<\/span> fd,<\/span> 0<\/span>)<\/span>;<\/span>
    \n\/\/ \u2605 base \u548c base2 \u662f\u4e0d\u540c\u7684\u865a\u62df\u5730\u5740，\u6307\u5411\u540c\u4e00\u6279\u7269\u7406\u9875<\/span><\/p>\n

    \u6ce8\u610f：\u8fd9\u7c7b\u5185\u5b58\u4e0d backed by \u6587\u4ef6，\u662f\u533f\u540d\u9875\u3002\u6240\u4ee5：<\/p>\n

      \n
    • \u4e0d\u4f1a\u5199\u56de\u78c1\u76d8<\/li>\n
    • \u5185\u5b58\u538b\u529b\u4e0b\u53ea\u80fd swap\/zram，\u4e0d\u80fd\u76f4\u63a5\u4e22<\/li>\n
    • \u4f46\u53ef\u4ee5 ASharedMemory_setProt \u6536\u7d27\u6743\u9650，\u6216\u7528 MADV_FREE\/purgeable \u8ba9\u5185\u6838\u53ef\u56de\u6536<\/li>\n<\/ul>\n
      \n

      \u7b2c 6 \u7ae0：\u5c04\u51fb\u6e38\u620f\u6848\u4f8b<\/h2>\n

      \u6848\u4f8b 1：\u7528 smaps \u770b\u6e05 LoadFromFile \u7684\u771f\u76f8<\/h3>\n

      \u505a\u6cd5：\u52a0\u8f7d\u4e00\u4e2a 80MB \u7684\u5730\u56fe bundle，\u7528 \/proc\/self\/smaps \u89c2\u5bdf\u3002<\/p>\n

      PID<\/span>=<\/span>$(<\/span>adb shell pidof com.xxx.game |<\/span> tr<\/span> -d<\/span> '\\\\r'<\/span>)<\/span><\/span>
      \nadb shell run-as com.xxx.game "grep -A 12 'base.bundle' \/proc\/$PID<\/span>\/smaps"<\/span><\/p>\n

      LoadFromFile \u4e4b\u540e\u7acb\u523b\u91c7\u6837：<\/p>\n

      7b2c000000-7b30f00000 r–p 00000000 fd:03 1234567 …\/base.bundle
      \nSize: 80128 kB \u2190 \u2605 \u865a\u62df\u5730\u5740\u8303\u56f4 80MB
      \nRss: 1436 kB \u2190 \u2605 \u5b9e\u9645\u9a7b\u7559\u53ea\u6709 1.4MB！
      \nPss: 1436 kB
      \nShared_Clean: 0 kB
      \nPrivate_Clean: 1436 kB \u2190 \u5e72\u51c0\u7684\u79c1\u6709\u6587\u4ef6\u9875
      \nPrivate_Dirty: 0 kB
      \nSwap: 0 kB<\/p>\n

      Size 80MB，Rss \u53ea\u6709 1.4MB\u3002 \u8fd9 1.4MB \u662f Unity \u8bfb\u7684\u5143\u6570\u636e（AssetBundle \u5934\u3001\u5bf9\u8c61\u7d22\u5f15\u8868）\u3002<\/p>\n

      \u5b9e\u4f8b\u5316\u4e86\u5730\u56fe Prefab \u4e4b\u540e\u518d\u770b：<\/p>\n

      Size: 80128 kB
      \nRss: 47280 kB \u2190 \u2605 \u6da8\u5230 46MB（\u7528\u5230\u7684\u90e8\u5206\u88ab fault \u8fdb\u6765\u4e86）
      \nPrivate_Clean: 47280 kB<\/p>\n

      \u5bf9\u6bd4 LoadFromMemory：<\/p>\n

      # \u6ca1\u6709 base.bundle \u7684 VMA（\u56e0\u4e3a\u4e0d\u662f\u6620\u5c04，\u662f\u62f7\u8fdb\u5806\u91cc）
      \n# \u4f46\u770b Native Heap
      \nadb shell "dumpsys meminfo $PID | grep 'Native Heap'"
      \nNative Heap 492580 492100 \u2190 \u6da8\u4e86 80MB（bundle \u526f\u672c）
      \n# \u52a0\u4e0a File.ReadAllBytes \u90a3 80MB \u5728\u6258\u7ba1\u5806（LOH）<\/p>\n

      \u7ed3\u8bba\u4e00\u76ee\u4e86\u7136：<\/p>\n\nLoadFromFileLoadFromMemory<\/tr>\n\n\n\n\n\n
      \u865a\u62df\u5730\u5740\u5360\u7528<\/td>\n80 MB<\/td>\n0（\u4e0d\u6620\u5c04）<\/td>\n<\/tr>\n
      \u5b9e\u9645\u7269\u7406\u5185\u5b58<\/td>\n1.4 MB \u2192 46 MB（\u6309\u9700）<\/td>\n160 MB（80\u00d72）<\/td>\n<\/tr>\n
      \u5185\u5b58\u5f52\u7c7b<\/td>\nfile-backed clean，\u53ef\u56de\u6536<\/td>\nanon + LOH，\u4e0d\u53ef\u56de\u6536<\/td>\n<\/tr>\n
      LMK \u773c\u91cc<\/td>\n\u4fbf\u5b9c<\/td>\n\u6602\u8d35<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
      \n

      \u6848\u4f8b 2：Major Fault \u98ce\u66b4\u2014\u2014\u6700\u96be\u67e5\u7684\u6218\u6597\u5361\u987f<\/h3>\n

      \u73b0\u8c61<\/h4>\n

      \u67d0\u5c04\u51fb\u6e38\u620f\u6539\u7528 LoadFromFile \u540e，\u542f\u52a8\u5feb\u4e86\u3001\u5185\u5b58\u4f4e\u4e86，\u4f46\u6218\u6597\u4e2d\u5076\u53d1 40~90ms \u5361\u987f\u3002Unity Profiler \u663e\u793a\u5361\u5728\u4e00\u4e2a\u666e\u901a\u7684 Instantiate \u4e0a，\u770b\u4e0d\u51fa\u539f\u56e0\u3002<\/p>\n

      \u4e3a\u4ec0\u4e48 Profiler \u770b\u4e0d\u89c1<\/h4>\n

      major fault \u53d1\u751f\u65f6：
      \n \u5185\u6838\u5728\u3010\u4f60\u7684\u7ebf\u7a0b\u4e0a\u4e0b\u6587\u3011\u91cc\u7761\u7720\u7b49 IO
      \n \u2192 \u4ece Profiler \u89d2\u5ea6，\u5c31\u662f"\u8fd9\u4e2a\u51fd\u6570\u6267\u884c\u4e86\u5f88\u4e45"
      \n \u2192 \u4f46\u51fd\u6570\u91cc\u6ca1\u6709\u4efb\u4f55\u8017\u65f6\u4ee3\u7801
      \n \u2192 CPU \u91c7\u6837\u5668（simpleperf）\u4e5f\u770b\u4e0d\u5230，\u56e0\u4e3a\u7ebf\u7a0b\u5728\u7761\u89c9\u4e0d\u5728\u8dd1<\/p>\n

      \u7528 \/proc \u6293\u73b0\u573a<\/h4>\n

      #!\/bin\/bash<\/span>
      \nPID<\/span>=<\/span>$(<\/span>adb shell pidof com.xxx.game |<\/span> tr<\/span> -d<\/span> '\\\\r'<\/span>)<\/span><\/span>
      \nprev_maj<\/span>=<\/span>0<\/span>;<\/span> prev_min<\/span>=<\/span>0<\/span>
      \necho<\/span> "sec,minflt_delta,majflt_delta"<\/span>
      \nfor<\/span> i<\/span> in<\/span> $(<\/span>seq<\/span> 1<\/span> 120<\/span>)<\/span><\/span>;<\/span> do<\/span>
      \n S<\/span>=<\/span>$(<\/span>adb shell cat<\/span> \/proc\/$PID\/stat |<\/span> tr<\/span> -d<\/span> '\\\\r'<\/span>)<\/span><\/span>
      \n MIN<\/span>=<\/span>$(<\/span>echo<\/span> $S |<\/span> awk<\/span> '{print $10}'<\/span>)<\/span><\/span>
      \n MAJ<\/span>=<\/span>$(<\/span>echo<\/span> $S |<\/span> awk<\/span> '{print $12}'<\/span>)<\/span><\/span>
      \n echo<\/span> "$i<\/span>,$((<\/span>MIN–<\/span>prev_min))<\/span><\/span>,$((<\/span>MAJ–<\/span>prev_maj))<\/span><\/span>"<\/span>
      \n prev_min<\/span>=<\/span>$MIN<\/span>;<\/span> prev_maj<\/span>=<\/span>$MAJ<\/span>
      \n sleep<\/span> 1<\/span>
      \ndone<\/span><\/p>\n

      \u8f93\u51fa：<\/p>\n

      sec minflt_delta majflt_delta \u73b0\u573a
      \n5 412 3 \u5f85\u673a
      \n30 1820 18 \u8df3\u4f1e
      \n78 6240 2104 \u2605 \u654c\u4eba\u8fdb\u89c6\u91ce，\u52a0\u8f7d\u76ae\u80a4+\u6b66\u5668
      \n79 3180 1876 \u2605 \u7ee7\u7eed
      \n80 890 142<\/p>\n

      2104 \u6b21 major fault \u00d7 ~150\u03bcs \u2248 315ms \u7684\u78c1\u76d8\u7b49\u5f85，\u5206\u6563\u5728\u51e0\u5e27\u91cc \u2192 \u5c31\u662f\u90a3\u4e2a 90ms \u5361\u987f\u3002<\/p>\n

      \u7cbe\u786e\u5b9a\u4f4d：mincore<\/h4>\n

      \u60f3\u77e5\u9053"\u5177\u4f53\u54ea\u4e9b\u9875\u4e0d\u5728\u5185\u5b58"：<\/p>\n

      \/\/ \u67e5\u8be2\u4e00\u6bb5\u6620\u5c04\u6709\u54ea\u4e9b\u9875\u5df2\u9a7b\u7559<\/span>
      \nint<\/span> check_residency<\/span>(<\/span>void<\/span>*<\/span> addr,<\/span> size_t<\/span> len,<\/span> int<\/span>*<\/span> resident,<\/span> int<\/span>*<\/span> total)<\/span>
      \n{<\/span>
      \n size_t<\/span> pages =<\/span> (<\/span>len +<\/span> 4095<\/span>)<\/span> \/<\/span> 4096<\/span>;<\/span>
      \n unsigned<\/span> char<\/span>*<\/span> vec =<\/span> malloc<\/span>(<\/span>pages)<\/span>;<\/span>
      \n if<\/span> (<\/span>mincore<\/span>(<\/span>addr,<\/span> len,<\/span> vec)<\/span> !=<\/span> 0<\/span>)<\/span> {<\/span> free<\/span>(<\/span>vec)<\/span>;<\/span> return<\/span> –<\/span>1<\/span>;<\/span> }<\/span><\/p>\n

      int<\/span> r =<\/span> 0<\/span>;<\/span>
      \n for<\/span> (<\/span>size_t<\/span> i =<\/span> 0<\/span>;<\/span> i <<\/span> pages;<\/span> i++<\/span>)<\/span>
      \n if<\/span> (<\/span>vec[<\/span>i]<\/span> &<\/span> 1<\/span>)<\/span> r++<\/span>;<\/span> \/\/ bit0 = \u5df2\u5728\u5185\u5b58<\/span><\/p>\n

      *<\/span>resident =<\/span> r;<\/span> *<\/span>total =<\/span> pages;<\/span>
      \n free<\/span>(<\/span>vec)<\/span>;<\/span>
      \n return<\/span> 0<\/span>;<\/span>
      \n}<\/span><\/p>\n

      \/\/ \u52a0\u8f7d\u524d\u540e\u6253\u70b9<\/span>
      \nDebug.<\/span>Log<\/span>(<\/span>$"[MMAP] <\/span>{<\/span>bundleName<\/span>}<\/span><\/span>: <\/span>{<\/span>resident<\/span>}<\/span><\/span>\/<\/span>{<\/span>total<\/span>}<\/span><\/span> pages resident "<\/span><\/span> +<\/span>
      \n $"(<\/span>{<\/span>resident *<\/span> 100<\/span> \/<\/span> total<\/span>}<\/span><\/span>%)"<\/span><\/span>)<\/span>;<\/span>
      \n\/\/ [MMAP] skin_yuki.bundle: 12\/512 pages resident (2%) \u2190 \u51e0\u4e4e\u5168\u8981 fault<\/span><\/p>\n

      \u4fee\u590d：\u5206\u7ea7\u9884\u70ed<\/h4>\n

      \u6838\u5fc3\u601d\u8def：\u628a\u4e0d\u53ef\u9884\u6d4b\u7684 fault \u6210\u672c，\u632a\u5230\u73a9\u5bb6\u80fd\u63a5\u53d7\u7684\u65f6\u523b\u3002<\/p>\n

      \/\/ Plugins\/Android\/src\/prefetch.c<\/span>
      \n#<\/span>include<\/span> <sys\/mman.h><\/span><\/span>
      \n#<\/span>include<\/span> <fcntl.h><\/span><\/span>
      \n#<\/span>include<\/span> <unistd.h><\/span><\/span><\/p>\n

      \/\/ \u6e29\u548c\u65b9\u5f0f：\u8ba9\u5185\u6838\u540e\u53f0\u9884\u8bfb，\u4e0d\u963b\u585e<\/span>
      \nint<\/span> warm_hint<\/span>(<\/span>const<\/span> char<\/span>*<\/span> path,<\/span> off_t<\/span> off,<\/span> size_t<\/span> len)<\/span>
      \n{<\/span>
      \n int<\/span> fd =<\/span> open<\/span>(<\/span>path,<\/span> O_RDONLY)<\/span>;<\/span>
      \n if<\/span> (<\/span>fd <<\/span> 0<\/span>)<\/span> return<\/span> –<\/span>1<\/span>;<\/span>
      \n posix_fadvise<\/span>(<\/span>fd,<\/span> off,<\/span> len,<\/span> POSIX_FADV_WILLNEED)<\/span>;<\/span> \/\/ \u5185\u6838\u5f02\u6b65\u9884\u8bfb<\/span>
      \n close<\/span>(<\/span>fd)<\/span>;<\/span>
      \n return<\/span> 0<\/span>;<\/span>
      \n}<\/span><\/p>\n

      \/\/ \u5f3a\u529b\u65b9\u5f0f：\u6620\u5c04\u540e\u4e3b\u52a8 touch，\u4fdd\u8bc1\u4e00\u5b9a\u8fdb page cache<\/span>
      \nint<\/span> warm_force<\/span>(<\/span>const<\/span> char<\/span>*<\/span> path,<\/span> off_t<\/span> off,<\/span> size_t<\/span> len)<\/span>
      \n{<\/span>
      \n int<\/span> fd =<\/span> open<\/span>(<\/span>path,<\/span> O_RDONLY)<\/span>;<\/span>
      \n if<\/span> (<\/span>fd <<\/span> 0<\/span>)<\/span> return<\/span> –<\/span>1<\/span>;<\/span><\/p>\n

      off_t<\/span> aligned =<\/span> off &<\/span> ~<\/span>(<\/span>off_t<\/span>)<\/span>(<\/span>sysconf<\/span>(<\/span>_SC_PAGESIZE)<\/span> –<\/span> 1<\/span>)<\/span>;<\/span>
      \n size_t<\/span> delta =<\/span> off –<\/span> aligned;<\/span>
      \n void<\/span>*<\/span> p =<\/span> mmap<\/span>(<\/span>NULL<\/span>,<\/span> len +<\/span> delta,<\/span> PROT_READ,<\/span> MAP_PRIVATE,<\/span> fd,<\/span> aligned)<\/span>;<\/span>
      \n if<\/span> (<\/span>p ==<\/span> MAP_FAILED)<\/span> {<\/span> close<\/span>(<\/span>fd)<\/span>;<\/span> return<\/span> –<\/span>2<\/span>;<\/span> }<\/span><\/p>\n

      madvise<\/span>(<\/span>p,<\/span> len +<\/span> delta,<\/span> MADV_WILLNEED)<\/span>;<\/span><\/p>\n

      \/\/ \u2605 \u6bcf\u9875\u8bfb\u4e00\u5b57\u8282，\u5f3a\u5236 fault \u8fdb\u6765<\/span>
      \n volatile<\/span> unsigned<\/span> char<\/span> sink =<\/span> 0<\/span>;<\/span>
      \n size_t<\/span> ps =<\/span> sysconf<\/span>(<\/span>_SC_PAGESIZE)<\/span>;<\/span>
      \n for<\/span> (<\/span>size_t<\/span> i =<\/span> 0<\/span>;<\/span> i <<\/span> len +<\/span> delta;<\/span> i +=<\/span> ps)<\/span>
      \n sink ^=<\/span> (<\/span>(<\/span>volatile<\/span> unsigned<\/span> char<\/span>*<\/span>)<\/span>p)<\/span>[<\/span>i]<\/span>;<\/span><\/p>\n

      munmap<\/span>(<\/span>p,<\/span> len +<\/span> delta)<\/span>;<\/span> \/\/ \u2605 \u89e3\u9664\u6620\u5c04，\u4f46 page cache \u91cc\u7684\u9875\u7559\u7740！<\/span>
      \n close<\/span>(<\/span>fd)<\/span>;<\/span>
      \n return<\/span> 0<\/span>;<\/span>
      \n}<\/span><\/p>\n

      \u5173\u952e\u70b9：munmap \u4e4b\u540e page cache \u91cc\u7684\u9875\u4e0d\u4f1a\u6d88\u5931\u3002 \u6211\u4eec\u53ea\u662f\u501f\u8fd9\u4e2a\u6620\u5c04\u53bb"\u6572\u9192"\u90a3\u4e9b\u9875\u3002<\/p>\n

      public<\/span> class<\/span> BundleWarmup<\/span>
      \n{<\/span>
      \n [<\/span>DllImport<\/span>(<\/span>"prefetch"<\/span>)<\/span><\/span><\/span>]<\/span> static<\/span> extern<\/span> int<\/span><\/span> warm_hint<\/span>(<\/span>string<\/span><\/span> p,<\/span> long<\/span><\/span> off,<\/span> ulong<\/span><\/span> len)<\/span>;<\/span>
      \n [<\/span>DllImport<\/span>(<\/span>"prefetch"<\/span>)<\/span><\/span><\/span>]<\/span> static<\/span> extern<\/span> int<\/span><\/span> warm_force<\/span>(<\/span>string<\/span><\/span> p,<\/span> long<\/span><\/span> off,<\/span> ulong<\/span><\/span> len)<\/span>;<\/span><\/p>\n

      \/\/ \u2605 \u5f00\u5c40\u524d，\u5728\u540e\u53f0\u7ebf\u7a0b\u9884\u70ed\u672c\u5c40\u5fc5\u9700\u8d44\u6e90<\/span>
      \n public<\/span> async<\/span> Task<\/span> WarmupForMatch<\/span>(<\/span>MatchInfo<\/span> m)<\/span>
      \n {<\/span>
      \n \/\/ \u5206\u7ea7：\u6838\u5fc3\u8d44\u6e90\u5f3a\u529b\u9884\u70ed，\u6b21\u8981\u8d44\u6e90\u53ea\u7ed9\u63d0\u793a<\/span>
      \n var<\/span><\/span> critical =<\/span> ResolveCritical<\/span>(<\/span>m)<\/span>;<\/span> \/\/ \u672c\u5c40\u5730\u56fe\u300110 \u4eba\u76ae\u80a4\u3001\u5e38\u7528\u6b66\u5668<\/span>
      \n var<\/span><\/span> optional =<\/span> ResolveOptional<\/span>(<\/span>m)<\/span>;<\/span> \/\/ \u8f7d\u5177\u3001\u7a00\u6709\u6b66\u5668<\/span><\/p>\n

      await<\/span> Task.<\/span>Run<\/span>(<\/span>(<\/span>)<\/span> =><\/span> {<\/span>
      \n foreach<\/span> (<\/span>var<\/span><\/span> b in<\/span> critical)<\/span> {<\/span>
      \n var<\/span><\/span> e =<\/span> packIndex[<\/span>b]<\/span>;<\/span>
      \n warm_force<\/span>(<\/span>packPath,<\/span> (<\/span>long<\/span>)<\/span>e.<\/span>offset,<\/span> e.<\/span>length)<\/span>;<\/span>
      \n }<\/span>
      \n foreach<\/span> (<\/span>var<\/span><\/span> b in<\/span> optional)<\/span> {<\/span>
      \n var<\/span><\/span> e =<\/span> packIndex[<\/span>b]<\/span>;<\/span>
      \n warm_hint<\/span>(<\/span>packPath,<\/span> (<\/span>long<\/span>)<\/span>e.<\/span>offset,<\/span> e.<\/span>length)<\/span>;<\/span> \/\/ \u4e0d\u963b\u585e<\/span>
      \n }<\/span>
      \n }<\/span>)<\/span>;<\/span><\/p>\n

      \/\/ \u9884\u70ed\u5b8c\u6210\u540e\u518d LoadFromFile \u2014\u2014 \u6b64\u65f6\u51e0\u4e4e\u5168\u662f minor fault<\/span>
      \n foreach<\/span> (<\/span>var<\/span><\/span> b in<\/span> critical)<\/span>
      \n loaded[<\/span>b]<\/span> =<\/span> AssetBundle.<\/span>LoadFromFile<\/span>(<\/span>packPath,<\/span> 0<\/span>,<\/span> packIndex[<\/span>b]<\/span>.<\/span>offset)<\/span>;<\/span>
      \n }<\/span>
      \n}<\/span><\/p>\n

      \u6548\u679c<\/h4>\n\n\u6307\u6807\u4fee\u590d\u524d\u4fee\u590d\u540e<\/tr>\n\n\n\n\n\n
      \u52a0\u8f7d\u754c\u9762\u65f6\u957f<\/td>\n1.2 s<\/td>\n3.6 s<\/td>\n<\/tr>\n
      \u6218\u6597\u4e2d majflt \u5cf0\u503c<\/td>\n2104 \/s<\/td>\n< 60 \/s<\/td>\n<\/tr>\n
      \u5e27\u65f6\u95f4 P99<\/td>\n47 ms<\/td>\n11 ms<\/td>\n<\/tr>\n
      \u5cf0\u503c PSS<\/td>\n720 MB<\/td>\n780 MB<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

      \u4ee3\u4ef7\u662f\u52a0\u8f7d\u6162\u4e86 2.4 \u79d2\u3001\u5185\u5b58\u591a 60MB，\u6362\u6765\u6218\u6597\u5168\u7a0b\u7a33\u5b9a\u3002 \u5bf9\u5c04\u51fb\u6e38\u620f\u8fd9\u7b14\u4ea4\u6613\u975e\u5e38\u5212\u7b97\u3002<\/p>\n

      📌 \u672c\u6848\u4f8b\u7684\u6838\u5fc3\u6559\u8bad：
      \nmmap \u6ca1\u6709\u6d88\u9664\u6210\u672c，\u5b83\u628a"\u4e00\u6b21\u96c6\u4e2d\u7684\u5927\u62f7\u8d1d"\u6362\u6210\u4e86"\u5206\u6563\u7684\u3001\u4e0d\u53ef\u9884\u6d4b\u7684 page fault"\u3002
      \n\u4f18\u5316\u7684\u672c\u8d28\u662f\u63a7\u5236\u6210\u672c\u53d1\u751f\u7684\u65f6\u673a，\u4e0d\u662f\u6d88\u9664\u6210\u672c\u3002<\/p>\n

      \n

      \u6848\u4f8b 3：mmap \u73af\u5f62\u7f13\u51b2\u2014\u2014\u4e3a\u4ec0\u4e48 SIGKILL \u4e5f\u4e0d\u4e22\u6570\u636e<\/h3>\n

      \u9700\u6c42<\/h4>\n

      Android LMK \u6740\u8fdb\u7a0b\u7528 SIGKILL，\u6ca1\u6709\u4efb\u4f55\u56de\u8c03\u2014\u2014finally\u3001OnApplicationQuit\u3001onDestroy \u5168\u90e8\u4e0d\u6267\u884c\u3002\u4f46\u6211\u4eec\u9700\u8981\u5d29\u6e83\u524d\u7684\u6700\u540e\u51e0\u5343\u6761\u4e8b\u4ef6\u6765\u5b9a\u4f4d\u95ee\u9898\u3002<\/p>\n

      \u4e3a\u4ec0\u4e48\u666e\u901a\u5199\u5165\u4f1a\u4e22<\/h4>\n

      \u4f60\u7684 byte[]
      \n \u2193 FileStream.Write
      \nFileStream \u5185\u90e8\u7f13\u51b2（\u7528\u6237\u6001！） \u2190 \u2605 SIGKILL \u65f6\u8fd9\u91cc\u7684\u6570\u636e\u76f4\u63a5\u84b8\u53d1
      \n \u2193 write() \u7cfb\u7edf\u8c03\u7528
      \n\u5185\u6838 page cache
      \n \u2193 writeback
      \n\u78c1\u76d8<\/p>\n

      \u4e3a\u4ec0\u4e48 mmap \u4e0d\u4f1a\u4e22<\/h4>\n

      \u4f60\u5199\u5165 mmap \u533a\u57df
      \n = \u76f4\u63a5\u5199\u7269\u7406\u5185\u5b58
      \n = \u8fd9\u5757\u7269\u7406\u5185\u5b58\u3010\u5c31\u662f\u3011page cache \u7684\u9875
      \n \u2193 PTE dirty \u4f4d\u7f6e 1，\u5185\u6838\u6807\u8bb0 PageDirty
      \n \u2193 \u8fdb\u7a0b\u88ab SIGKILL：\u8fdb\u7a0b\u6b7b\u4e86，\u4f46 page cache \u9875\u5f52\u5185\u6838\u7ba1
      \n \u2193 writeback \u5185\u6838\u7ebf\u7a0b\u7167\u5e38\u628a\u810f\u9875\u5199\u56de\u6587\u4ef6
      \n\u78c1\u76d8 \u2705 \u6570\u636e\u5728<\/p>\n

      \u552f\u4e00\u4f1a\u4e22\u7684\u60c5\u51b5：\u5185\u6838\u5d29\u6e83 \/ \u65ad\u7535 \/ \u5f3a\u5236\u62d4\u7535\u6c60\u3002\u8fd9\u4e2a\u6982\u7387\u6bd4 LMK \u6740\u8fdb\u7a0b\u4f4e\u51e0\u4e2a\u6570\u91cf\u7ea7\u3002<\/p>\n

      \u5b9e\u73b0<\/h4>\n

      \/\/ mmap_ring.c<\/span>
      \n#<\/span>include<\/span> <sys\/mman.h><\/span><\/span>
      \n#<\/span>include<\/span> <fcntl.h><\/span><\/span>
      \n#<\/span>include<\/span> <unistd.h><\/span><\/span>
      \n#<\/span>include<\/span> <stdatomic.h><\/span><\/span>
      \n#<\/span>include<\/span> <string.h><\/span><\/span><\/p>\n

      typedef<\/span> struct<\/span> {<\/span>
      \n uint32_t<\/span> magic,<\/span> version,<\/span> capacity,<\/span> _pad;<\/span>
      \n _Atomic<\/span> uint64_t<\/span> cursor;<\/span> \/\/ \u5355\u8c03\u9012\u589e，\u4e0d\u56de\u7ed5<\/span>
      \n}<\/span> RingHdr;<\/span><\/p>\n

      static<\/span> void<\/span>*<\/span> g_base =<\/span> NULL<\/span>;<\/span>
      \nstatic<\/span> size_t<\/span> g_size =<\/span> 0<\/span>;<\/span>
      \nstatic<\/span> RingHdr*<\/span> g_hdr =<\/span> NULL<\/span>;<\/span>
      \nstatic<\/span> uint8_t<\/span>*<\/span> g_data =<\/span> NULL<\/span>;<\/span><\/p>\n

      int<\/span> ring_open<\/span>(<\/span>const<\/span> char<\/span>*<\/span> path,<\/span> uint32_t<\/span> cap)<\/span>
      \n{<\/span>
      \n int<\/span> fd =<\/span> open<\/span>(<\/span>path,<\/span> O_RDWR |<\/span> O_CREAT,<\/span> 0600<\/span>)<\/span>;<\/span>
      \n if<\/span> (<\/span>fd <<\/span> 0<\/span>)<\/span> return<\/span> –<\/span>1<\/span>;<\/span><\/p>\n

      g_size =<\/span> sizeof<\/span>(<\/span>RingHdr)<\/span> +<\/span> cap;<\/span><\/p>\n

      \/\/ \u2605\u2605 \u5fc5\u987b\u5148 ftruncate！<\/span>
      \n \/\/ mmap \u8d85\u51fa\u6587\u4ef6\u672b\u5c3e\u7684\u533a\u57df，\u8bbf\u95ee\u65f6\u662f SIGBUS \u800c\u4e0d\u662f\u81ea\u52a8\u6269\u5c55<\/span>
      \n if<\/span> (<\/span>ftruncate<\/span>(<\/span>fd,<\/span> g_size)<\/span> !=<\/span> 0<\/span>)<\/span> {<\/span> close<\/span>(<\/span>fd)<\/span>;<\/span> return<\/span> –<\/span>2<\/span>;<\/span> }<\/span><\/p>\n

      \/\/ \u2605\u2605 MAP_SHARED \u2014\u2014 MAP_PRIVATE \u4f1a COW，\u6c38\u8fdc\u5199\u4e0d\u8fdb\u6587\u4ef6<\/span>
      \n g_base =<\/span> mmap<\/span>(<\/span>NULL<\/span>,<\/span> g_size,<\/span> PROT_READ|<\/span>PROT_WRITE,<\/span> MAP_SHARED,<\/span> fd,<\/span> 0<\/span>)<\/span>;<\/span>
      \n close<\/span>(<\/span>fd)<\/span>;<\/span> \/\/ \u2605 mmap \u5efa\u7acb\u540e fd \u53ef\u5173，\u6620\u5c04\u72ec\u7acb\u6301\u6709 inode \u5f15\u7528<\/span>
      \n if<\/span> (<\/span>g_base ==<\/span> MAP_FAILED)<\/span> return<\/span> –<\/span>3<\/span>;<\/span><\/p>\n

      g_hdr =<\/span> (<\/span>RingHdr*<\/span>)<\/span>g_base;<\/span>
      \n g_data =<\/span> (<\/span>uint8_t<\/span>*<\/span>)<\/span>g_base +<\/span> sizeof<\/span>(<\/span>RingHdr)<\/span>;<\/span><\/p>\n

      if<\/span> (<\/span>g_hdr-><\/span>magic !=<\/span> 0x474E4952<\/span>)<\/span> {<\/span> \/\/ "RING"<\/span>
      \n g_hdr-><\/span>magic =<\/span> 0x474E4952<\/span>;<\/span>
      \n g_hdr-><\/span>version =<\/span> 1<\/span>;<\/span>
      \n g_hdr-><\/span>capacity =<\/span> cap;<\/span>
      \n atomic_store<\/span>(<\/span>&<\/span>g_hdr-><\/span>cursor,<\/span> 0<\/span>)<\/span>;<\/span>
      \n }<\/span>
      \n return<\/span> 0<\/span>;<\/span>
      \n}<\/span><\/p>\n

      \/\/ \u2605 \u5199\u5165：\u7eaf\u5185\u5b58\u64cd\u4f5c，\u96f6\u7cfb\u7edf\u8c03\u7528，\u7ea6 20 ns<\/span>
      \nvoid<\/span> ring_write<\/span>(<\/span>const<\/span> void<\/span>*<\/span> src,<\/span> uint32_t<\/span> len)<\/span>
      \n{<\/span>
      \n if<\/span> (<\/span>!<\/span>g_data ||<\/span> !<\/span>len ||<\/span> len ><\/span> g_hdr-><\/span>capacity)<\/span> return<\/span>;<\/span><\/p>\n

      uint64_t<\/span> pos =<\/span> atomic_fetch_add_explicit<\/span>(<\/span>&<\/span>g_hdr-><\/span>cursor,<\/span> len,<\/span>
      \n memory_order_relaxed)<\/span>;<\/span>
      \n uint32_t<\/span> off =<\/span> (<\/span>uint32_t<\/span>)<\/span>(<\/span>pos %<\/span> g_hdr-><\/span>capacity)<\/span>;<\/span><\/p>\n

      if<\/span> (<\/span>off +<\/span> len <=<\/span> g_hdr-><\/span>capacity)<\/span> {<\/span>
      \n memcpy<\/span>(<\/span>g_data +<\/span> off,<\/span> src,<\/span> len)<\/span>;<\/span>
      \n }<\/span> else<\/span> {<\/span>
      \n uint32_t<\/span> first =<\/span> g_hdr-><\/span>capacity –<\/span> off;<\/span>
      \n memcpy<\/span>(<\/span>g_data +<\/span> off,<\/span> src,<\/span> first)<\/span>;<\/span>
      \n memcpy<\/span>(<\/span>g_data,<\/span> (<\/span>const<\/span> uint8_t<\/span>*<\/span>)<\/span>src +<\/span> first,<\/span> len –<\/span> first)<\/span>;<\/span>
      \n }<\/span>
      \n}<\/span><\/p>\n

      \/\/ \u5173\u952e\u8282\u70b9\u4e3b\u52a8\u50ac\u4e00\u4e0b\u5199\u56de（\u5f02\u6b65，\u4e0d\u963b\u585e）<\/span>
      \nvoid<\/span> ring_flush<\/span>(<\/span>void<\/span>)<\/span> {<\/span> if<\/span> (<\/span>g_base)<\/span> msync<\/span>(<\/span>g_base,<\/span> g_size,<\/span> MS_ASYNC)<\/span>;<\/span> }<\/span><\/p>\n

      C# \u4fa7：\u96f6\u5206\u914d\u9762\u5305\u5c51<\/h4>\n

      public<\/span> enum<\/span> Crumb<\/span> :<\/span> byte<\/span><\/span> {<\/span>
      \n MapLoadBegin =<\/span> 1<\/span>,<\/span> MapLoadEnd,<\/span> PlayerSpawn,<\/span> WeaponSwitch,<\/span>
      \n BundleLoad,<\/span> VfxSpawn,<\/span> MemPressure,<\/span> NetReconnect,<\/span> MajorFaultBurst,<\/span>
      \n}<\/span><\/p>\n

      public<\/span> static<\/span> class<\/span> Breadcrumb<\/span>
      \n{<\/span>
      \n [<\/span>DllImport<\/span>(<\/span>"mmap_ring"<\/span>)<\/span><\/span><\/span>]<\/span> static<\/span> extern<\/span> int<\/span><\/span> ring_open<\/span>(<\/span>string<\/span><\/span> p,<\/span> uint<\/span><\/span> cap)<\/span>;<\/span>
      \n [<\/span>DllImport<\/span>(<\/span>"mmap_ring"<\/span>)<\/span><\/span><\/span>]<\/span> static<\/span> extern<\/span> void<\/span><\/span> ring_write<\/span>(<\/span>IntPtr<\/span> src,<\/span> uint<\/span><\/span> len)<\/span>;<\/span>
      \n [<\/span>DllImport<\/span>(<\/span>"mmap_ring"<\/span>)<\/span><\/span><\/span>]<\/span> static<\/span> extern<\/span> void<\/span><\/span> ring_flush<\/span>(<\/span>)<\/span>;<\/span><\/p>\n

      public<\/span> static<\/span> void<\/span><\/span> Init<\/span>(<\/span>)<\/span> {<\/span>
      \n \/\/ \u2605 \u5fc5\u987b\u653e\u5185\u90e8\u5b58\u50a8，\u5916\u90e8\u5b58\u50a8\u8d70 FUSE，mmap \u6027\u80fd\u5dee<\/span>
      \n string<\/span><\/span> p =<\/span> Path.<\/span>Combine<\/span>(<\/span>Application.<\/span>persistentDataPath,<\/span> "logs\/crumb.ring"<\/span>)<\/span>;<\/span>
      \n Directory.<\/span>CreateDirectory<\/span>(<\/span>Path.<\/span>GetDirectoryName<\/span>(<\/span>p)<\/span>)<\/span>;<\/span>
      \n ring_open<\/span>(<\/span>p,<\/span> 256<\/span> *<\/span> 1024<\/span>)<\/span>;<\/span> \/\/ 256KB \u2248 65536 \u6761<\/span>
      \n }<\/span><\/p>\n

      public<\/span> static<\/span> unsafe<\/span> void<\/span><\/span> Mark<\/span>(<\/span>Crumb<\/span> id,<\/span> ushort<\/span><\/span> param)<\/span> {<\/span>
      \n byte<\/span>*<\/span> b =<\/span> stackalloc<\/span> byte<\/span>[<\/span>4<\/span>]<\/span>;<\/span> \/\/ \u6808\u4e0a，\u96f6 GC<\/span>
      \n b[<\/span>0<\/span>]<\/span> =<\/span> (<\/span>byte<\/span>)<\/span>id;<\/span>
      \n *<\/span>(<\/span>ushort<\/span>*<\/span>)<\/span>(<\/span>b +<\/span> 1<\/span>)<\/span> =<\/span> param;<\/span>
      \n b[<\/span>3<\/span>]<\/span> =<\/span> (<\/span>byte<\/span>)<\/span>(<\/span>Time.<\/span>frameCount &<\/span> 0xFF<\/span>)<\/span>;<\/span>
      \n ring_write<\/span>(<\/span>(<\/span>IntPtr)<\/span>b,<\/span> 4<\/span>)<\/span>;<\/span>
      \n }<\/span><\/p>\n

      \/\/ \u6b7b\u4ea1\u3001\u56de\u5408\u7ed3\u675f\u7b49\u5173\u952e\u70b9，\u50ac\u4e00\u6b21\u5199\u56de<\/span>
      \n public<\/span> static<\/span> void<\/span><\/span> Checkpoint<\/span>(<\/span>)<\/span> =><\/span> ring_flush<\/span>(<\/span>)<\/span>;<\/span>
      \n}<\/span><\/p>\n

      \u5d29\u6e83\u540e\u8bfb\u53d6<\/h4>\n

      void<\/span><\/span> Start<\/span>(<\/span>)<\/span> {<\/span>
      \n string<\/span><\/span> flag =<\/span> Path.<\/span>Combine<\/span>(<\/span>NoBackupDir<\/span>(<\/span>)<\/span>,<\/span> "crash_flag"<\/span>)<\/span>;<\/span>
      \n if<\/span> (<\/span>File.<\/span>Exists<\/span>(<\/span>flag)<\/span>)<\/span> {<\/span>
      \n \/\/ \u2605 \u4e0a\u6b21\u5f02\u5e38\u9000\u51fa，\u4f46\u5185\u6838\u4fdd\u4f4f\u4e86 mmap \u7684\u810f\u9875<\/span>
      \n var<\/span><\/span> crumbs =<\/span> ParseRing<\/span>(<\/span>ringPath)<\/span>;<\/span>
      \n UploadCrashContext<\/span>(<\/span>crumbs)<\/span>;<\/span> \/\/ "\u6b7b\u4e4b\u524d\u6700\u540e 65536 \u4e2a\u4e8b\u4ef6"<\/span>
      \n }<\/span>
      \n File.<\/span>WriteAllText<\/span>(<\/span>flag,<\/span> "1"<\/span>)<\/span>;<\/span>
      \n}<\/span>
      \nvoid<\/span><\/span> OnApplicationQuit<\/span>(<\/span>)<\/span> =><\/span> File.<\/span>Delete<\/span>(<\/span>..<\/span>.<\/span>)<\/span>;<\/span> \/\/ \u6b63\u5e38\u9000\u51fa\u624d\u5220<\/span><\/p>\n

      \u4e09\u79cd\u5199\u5165\u65b9\u5f0f\u5b9e\u6d4b<\/h4>\n\n\u65b9\u5f0f\u5355\u6b21\u8017\u65f6SIGKILL \u540e\u7cfb\u7edf\u8c03\u7528<\/tr>\n\n\n\n\n
      FileStream.Write<\/td>\n~800 ns<\/td>\n\u274c \u4e22\u5931<\/td>\n\u7f13\u51b2\u6ee1\u65f6<\/td>\n<\/tr>\n
      Write + Flush(true)<\/td>\n~2 ms<\/td>\n\u2705 \u4fdd\u7559<\/td>\n\u6bcf\u6b21 fsync<\/td>\n<\/tr>\n
      mmap \u5199\u5165<\/td>\n~20 ns<\/td>\n\u2705 \u4fdd\u7559<\/td>\n0<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

      mmap \u662f\u552f\u4e00\u540c\u65f6\u505a\u5230"\u5feb"\u548c"\u53ef\u9760"\u7684\u65b9\u6848，\u800c\u8fd9\u5b8c\u5168\u5f52\u529f\u4e8e"\u7528\u6237\u5730\u5740\u76f4\u63a5\u6307\u5411 page cache"\u3002<\/p>\n

      \n

      \u6848\u4f8b 4：LMK \u89c6\u89d2\u2014\u2014mmap \u8ba9\u4f60\u66f4\u96be\u88ab\u6740<\/h3>\n

      \u539f\u7406<\/h4>\n

      Android LMK \u8ba1\u7b97\u6740\u8c01\u65f6，\u770b\u7684\u662f"\u6740\u4e86\u4f60\u80fd\u91ca\u653e\u591a\u5c11"\u3002\u800c\u4e0d\u540c\u7c7b\u578b\u7684\u5185\u5b58"\u91ca\u653e\u6210\u672c"\u5b8c\u5168\u4e0d\u540c：<\/p>\n

      \u4f60\u7684 1GB \u5185\u5b58\u6784\u6210 A（LoadFromMemory \u8def\u7ebf）：
      \n \u251c\u2500 400 MB Native Heap（\u533f\u540d\u9875）\u2192 \u5fc5\u987b\u6740\u8fdb\u7a0b\u624d\u80fd\u91ca\u653e
      \n \u251c\u2500 300 MB \u6258\u7ba1\u5806（\u533f\u540d\u9875） \u2192 \u5fc5\u987b\u6740\u8fdb\u7a0b
      \n \u2514\u2500 300 MB \u663e\u5b58<\/p>\n

      \u4f60\u7684 1GB \u5185\u5b58\u6784\u6210 B（LoadFromFile \u8def\u7ebf）：
      \n \u251c\u2500 150 MB Native Heap（\u533f\u540d\u9875）
      \n \u251c\u2500 100 MB \u6258\u7ba1\u5806
      \n \u251c\u2500 450 MB file-backed clean（mmap \u7684 bundle）
      \n \u2502 \u2192 \u2605 kswapd \u53ef\u4ee5\u76f4\u63a5\u56de\u6536，\u4e0d\u9700\u8981\u6740\u4f60
      \n \u2514\u2500 300 MB \u663e\u5b58<\/p>\n

      \u5728\u5185\u5b58\u538b\u529b\u4e0b：<\/p>\n

        \n
      • \u6784\u6210 A：\u7cfb\u7edf\u6ca1\u5f97\u9009，\u53ea\u80fd\u6740\u8fdb\u7a0b<\/li>\n
      • \u6784\u6210 B：\u7cfb\u7edf\u5148\u56de\u6536\u90a3 450MB \u5e72\u51c0\u6587\u4ef6\u9875 \u2192 \u4f60\u6d3b\u4e0b\u6765\u4e86（\u4ee3\u4ef7\u662f\u540e\u7eed major fault）<\/li>\n<\/ul>\n

        \u5b9e\u6d4b\u9a8c\u8bc1<\/h4>\n

        # \u5236\u9020\u5185\u5b58\u538b\u529b：\u540e\u53f0\u5f00\u4e00\u5806 App，\u7136\u540e\u89c2\u5bdf<\/span>
        \nadb shell "dumpsys meminfo com.xxx.game | grep -E '.apk mmap|Native Heap|TOTAL'"<\/span><\/p>\n

        \u6784\u6210 B \u7684\u8f93\u51fa：<\/p>\n

        Native Heap 152400 151900
        \n.apk mmap 458200 0 458200 \u2190 \u2605 Private Clean \u5168\u90e8\u53ef\u56de\u6536
        \nTOTAL 1010000 580000 430000<\/p>\n

        \u6ce8\u610f .apk mmap \u90a3\u4e00\u884c Private Dirty = 0，Private Clean = 458200\u3002<\/p>\n

        Private Clean \u5c31\u662f"\u968f\u65f6\u53ef\u4ee5\u4e22\u7684\u5185\u5b58"\u3002\u5b83\u867d\u7136\u8ba1\u5165 PSS，\u4f46\u5bf9 LMK \u6765\u8bf4\u662f"\u8f6f\u7684"\u3002<\/p>\n

        \u538b\u6d4b\u5bf9\u6bd4<\/h4>\n

        \u540c\u4e00\u53f0 4GB \u673a\u5668，\u540e\u53f0\u5f00 8 \u4e2a App，\u73a9 50 \u5c40：<\/p>\n\n\u52a0\u8f7d\u65b9\u5f0f\u5e73\u5747 PSS\u88ab LMK \u6740\u6b21\u6570\u6218\u6597\u5361\u987f P99<\/tr>\n\n\n\n\n
        LoadFromMemory<\/td>\n1180 MB<\/td>\n12 \/ 50<\/td>\n9 ms<\/td>\n<\/tr>\n
        LoadFromFile（\u65e0\u9884\u70ed）<\/td>\n720 MB<\/td>\n1 \/ 50<\/td>\n47 ms<\/td>\n<\/tr>\n
        LoadFromFile + \u9884\u70ed<\/td>\n780 MB<\/td>\n0 \/ 50<\/td>\n11 ms<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

        \u7b2c\u4e09\u884c\u662f\u6700\u4f18\u89e3：mmap \u63d0\u4f9b"\u53ef\u56de\u6536"\u7684\u5c5e\u6027\u907f\u514d\u88ab\u6740，\u9884\u70ed\u63d0\u4f9b"\u9875\u5df2\u9a7b\u7559"\u907f\u514d\u5361\u987f\u3002<\/p>\n

        \n

        \u6848\u4f8b 5：\u5927\u6587\u4ef6 Pack + Offset\u2014\u2014\u51cf\u5c11 VMA \u4e0e TLB \u538b\u529b<\/h3>\n

        \u95ee\u9898<\/h4>\n

        LoadFromFile \u6709\u4e2a\u5e26 offset \u7684\u91cd\u8f7d，\u4f46\u5f88\u591a\u4eba\u4e0d\u77e5\u9053\u4e3a\u4ec0\u4e48\u8981\u7528\u5b83：<\/p>\n

        public<\/span> static<\/span> AssetBundle<\/span> LoadFromFile<\/span>(<\/span>string<\/span><\/span> path,<\/span> uint<\/span><\/span> crc,<\/span> ulong<\/span><\/span> offset)<\/span>;<\/span><\/p>\n

        200 \u4e2a\u5c0f\u6587\u4ef6 vs 1 \u4e2a\u5927\u6587\u4ef6<\/h4>\n

        \u3010200 \u4e2a\u72ec\u7acb bundle\u3011
        \n \u251c\u2500 200 \u6b21 open\/close \u7cfb\u7edf\u8c03\u7528
        \n \u251c\u2500 200 \u4e2a VMA \u2192 VMA \u7ea2\u9ed1\u6811\u53d8\u6df1，\u6bcf\u6b21 fault \u67e5\u627e\u53d8\u6162
        \n \u251c\u2500 \u6587\u4ef6\u7cfb\u7edf\u5143\u6570\u636e：200 \u4e2a inode，\u6bcf\u4e2a\u81f3\u5c11\u5360 1 \u4e2a block
        \n \u251c\u2500 \u78c1\u76d8\u5e03\u5c40\u5206\u6563 \u2192 \u9884\u8bfb\u51e0\u4e4e\u65e0\u6548，\u5168\u662f\u968f\u673a IO
        \n \u2514\u2500 Android FUSE \u5c42\u6bcf\u4e2a\u6587\u4ef6\u90fd\u8981\u8f6c\u53d1<\/p>\n

        \u30101 \u4e2a\u5927 pack + offset\u3011
        \n \u251c\u2500 1 \u6b21 open
        \n \u251c\u2500 \u53ef\u4ee5\u53ea\u5efa 1 \u4e2a\u5927 VMA（\u5982\u679c\u4e00\u6b21\u6620\u5c04\u6574\u4e2a pack）
        \n \u251c\u2500 \u987a\u5e8f\u5e03\u5c40 \u2192 \u5185\u6838 readahead \u547d\u4e2d\u7387\u9ad8
        \n \u2514\u2500 fault-around \u80fd\u4e00\u6b21\u6620\u5c04 16 \u9875<\/p>\n

        \u5b9e\u73b0<\/h4>\n

        public<\/span> class<\/span> PackedBundleStore<\/span>
        \n{<\/span>
        \n \/\/ \u7d22\u5f15：name \u2192 (pageAlignedOffset, length, crc)<\/span>
        \n Dictionary<<\/span>string<\/span>,<\/span> PackEntry><\/span><\/span> index;<\/span>
        \n string<\/span><\/span> packPath;<\/span><\/p>\n

        public<\/span> AssetBundle<\/span> Load<\/span>(<\/span>string<\/span><\/span> name)<\/span> {<\/span>
        \n var<\/span><\/span> e =<\/span> index[<\/span>name]<\/span>;<\/span>
        \n \/\/ \u2605 offset \u5fc5\u987b\u9875\u5bf9\u9f50，\u6253\u5305\u5de5\u5177\u8981\u4fdd\u8bc1\u8fd9\u4e00\u70b9<\/span>
        \n return<\/span> AssetBundle.<\/span>LoadFromFile<\/span>(<\/span>packPath,<\/span> e.<\/span>crc,<\/span> e.<\/span>offset)<\/span>;<\/span>
        \n }<\/span>
        \n}<\/span><\/p>\n

        \u6253\u5305\u5de5\u5177\u7684\u5173\u952e\u7ea6\u675f：<\/p>\n

        \/\/ \u751f\u6210 pack \u65f6，\u6bcf\u4e2a bundle \u8d77\u59cb\u4f4d\u7f6e\u5bf9\u9f50\u5230 16KB<\/span>
        \n\/\/ （\u517c\u5bb9 Android 15 \u7684 16KB \u9875；4KB \u9875\u673a\u5668\u4e0a\u4e5f\u5b89\u5168）<\/span>
        \nconst<\/span> int<\/span><\/span> ALIGN =<\/span> 16<\/span> *<\/span> 1024<\/span>;<\/span><\/p>\n

        foreach<\/span> (<\/span>var<\/span><\/span> bundle in<\/span> bundles)<\/span> {<\/span>
        \n long<\/span><\/span> pad =<\/span> (<\/span>ALIGN –<\/span> (<\/span>writer.<\/span>Position %<\/span> ALIGN)<\/span>)<\/span> %<\/span> ALIGN;<\/span>
        \n writer.<\/span>Write<\/span>(<\/span>new<\/span> byte<\/span><\/span>[<\/span>pad]<\/span>)<\/span>;<\/span> \/\/ \u586b\u5145\u5bf9\u9f50<\/span>
        \n index[<\/span>bundle.<\/span>Name]<\/span> =<\/span> new<\/span> PackEntry<\/span> {<\/span>
        \n offset =<\/span> (<\/span>ulong<\/span>)<\/span>writer.<\/span>Position,<\/span>
        \n length =<\/span> (<\/span>ulong<\/span>)<\/span>bundle.<\/span>Length,<\/span>
        \n }<\/span>;<\/span>
        \n writer.<\/span>Write<\/span>(<\/span>bundle.<\/span>Data)<\/span>;<\/span>
        \n}<\/span><\/p>\n

        \u586b\u5145\u6d6a\u8d39：\u5e73\u5747\u6bcf\u4e2a bundle \u6d6a\u8d39 8KB，200 \u4e2a = 1.6MB\u3002\u6362\u6765\u7684\u662f\u52a0\u8f7d\u901f\u5ea6 3 \u500d\u63d0\u5347，\u975e\u5e38\u503c\u3002<\/p>\n

        \u5b9e\u6d4b<\/h4>\n\n\u65b9\u6848\u51b7\u542f\u52a8\u52a0\u8f7d 200 bundleVMA \u6570\u91cfmajflt<\/tr>\n\n\n\n
        200 \u4e2a\u72ec\u7acb\u6587\u4ef6<\/td>\n1820 ms<\/td>\n+200<\/td>\n4210<\/td>\n<\/tr>\n
        1 \u4e2a pack + offset<\/td>\n610 ms<\/td>\n+12<\/td>\n1180<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
        \n

        \u6848\u4f8b 6：\u8de8\u8fdb\u7a0b\u5171\u4eab\u2014\u2014\u5f55\u5236\u8fdb\u7a0b<\/h3>\n

        \u67b6\u6784：\u4e3b\u8fdb\u7a0b\u6e32\u67d3，\u72ec\u7acb\u8fdb\u7a0b\u505a\u7f16\u7801\u63a8\u6d41，\u907f\u514d\u7f16\u7801\u5360\u7528\u4e3b\u8fdb\u7a0b CPU\u3002<\/p>\n

        \u4e3b\u8fdb\u7a0b \u5f55\u5236\u8fdb\u7a0b
        \n \u251c\u2500 \u6e32\u67d3 \u2192 \u62ff\u5230\u5e27\u6570\u636e \u251c\u2500 H.264 \u7f16\u7801
        \n \u251c\u2500 \u97f3\u9891\u6df7\u97f3 \u2192 PCM \u2514\u2500 \u63a8\u6d41
        \n \u2514\u2500 \u9700\u8981\u4f20\u7ed9\u5f55\u5236\u8fdb\u7a0b<\/p>\n

        \u6bcf\u5e27 1080p RGBA = 8 MB
        \n60fps \u2192 480 MB\/s
        \n\u7528 Binder \u4f20 \u2192 \u2605 \u76f4\u63a5\u628a\u5185\u5b58\u5e26\u5bbd\u6253\u6b7b<\/p>\n

        \u5171\u4eab\u5185\u5b58\u65b9\u6848<\/h4>\n

        \/\/ \u4e3b\u8fdb\u7a0b：\u521b\u5efa<\/span>
        \nint<\/span> fd =<\/span> ASharedMemory_create<\/span>(<\/span>"frame_ring"<\/span>,<\/span> RING_BYTES)<\/span>;<\/span>
        \nvoid<\/span>*<\/span> base =<\/span> mmap<\/span>(<\/span>NULL<\/span>,<\/span> RING_BYTES,<\/span> PROT_READ|<\/span>PROT_WRITE,<\/span> MAP_SHARED,<\/span> fd,<\/span> 0<\/span>)<\/span>;<\/span>
        \n\/\/ \u901a\u8fc7 Binder \u4f20 fd（\u53ea\u4f20 fd，\u4e0d\u4f20\u6570\u636e！）<\/span><\/p>\n

        \/\/ \u5f55\u5236\u8fdb\u7a0b：\u6620\u5c04\u540c\u4e00\u6279\u7269\u7406\u9875<\/span>
        \nvoid<\/span>*<\/span> base2 =<\/span> mmap<\/span>(<\/span>NULL<\/span>,<\/span> RING_BYTES,<\/span> PROT_READ,<\/span> MAP_SHARED,<\/span> recv_fd,<\/span> 0<\/span>)<\/span>;<\/span><\/p>\n

        \u7269\u7406\u5185\u5b58
        \n\u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510
        \n\u2502 \u533f\u540d\u5171\u4eab\u9875（ashmem） \u2502
        \n\u2514\u2500\u2500\u252c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u252c\u2500\u2500\u2518
        \n \u2502 \u2502
        \n\u4e3b\u8fdb\u7a0b PTE \u5f55\u5236\u8fdb\u7a0b PTE
        \n（\u865a\u62df\u5730\u5740 A） （\u865a\u62df\u5730\u5740 B）<\/p>\n

        \u2605 \u4e24\u4e2a\u4e0d\u540c\u7684\u865a\u62df\u5730\u5740，\u540c\u4e00\u6279\u7269\u7406\u9875
        \n\u2605 \u4e3b\u8fdb\u7a0b\u5199\u5165 \u2192 \u5f55\u5236\u8fdb\u7a0b\u7acb\u523b\u53ef\u89c1，\u96f6\u62f7\u8d1d<\/p>\n

        \u65e0\u9501\u73af\u5f62\u961f\u5217<\/h4>\n

        typedef<\/span> struct<\/span> {<\/span>
        \n _Atomic<\/span> uint64_t<\/span> write_pos;<\/span> \/\/ \u53ea\u6709\u751f\u4ea7\u8005\u5199<\/span>
        \n _Atomic<\/span> uint64_t<\/span> read_pos;<\/span> \/\/ \u53ea\u6709\u6d88\u8d39\u8005\u5199<\/span>
        \n uint32_t<\/span> slots,<\/span> slot_size;<\/span>
        \n}<\/span> ShmRing;<\/span><\/p>\n

        \/\/ \u751f\u4ea7\u8005<\/span>
        \nbool push<\/span>(<\/span>ShmRing*<\/span> r,<\/span> uint8_t<\/span>*<\/span> data,<\/span> const<\/span> void<\/span>*<\/span> src)<\/span> {<\/span>
        \n uint64_t<\/span> w =<\/span> atomic_load_explicit<\/span>(<\/span>&<\/span>r-><\/span>write_pos,<\/span> memory_order_relaxed)<\/span>;<\/span>
        \n uint64_t<\/span> rd =<\/span> atomic_load_explicit<\/span>(<\/span>&<\/span>r-><\/span>read_pos,<\/span> memory_order_acquire)<\/span>;<\/span>
        \n if<\/span> (<\/span>w –<\/span> rd >=<\/span> r-><\/span>slots)<\/span> return<\/span> false;<\/span> \/\/ \u6ee1 \u2192 \u4e22\u5e27<\/span><\/p>\n

        memcpy<\/span>(<\/span>data +<\/span> (<\/span>w %<\/span> r-><\/span>slots)<\/span> *<\/span> r-><\/span>slot_size,<\/span> src,<\/span> r-><\/span>slot_size)<\/span>;<\/span><\/p>\n

        \/\/ \u2605 release：\u4fdd\u8bc1 memcpy \u5bf9\u6d88\u8d39\u8005\u53ef\u89c1\u540e\u624d\u66f4\u65b0\u6e38\u6807<\/span>
        \n atomic_store_explicit<\/span>(<\/span>&<\/span>r-><\/span>write_pos,<\/span> w +<\/span> 1<\/span>,<\/span> memory_order_release)<\/span>;<\/span>
        \n return<\/span> true;<\/span>
        \n}<\/span><\/p>\n

        \u4e09\u4e2a\u5fc5\u987b\u77e5\u9053\u7684\u5751<\/h4>\n

        \u2460 \u7edd\u5bf9\u4e0d\u80fd\u5728\u5171\u4eab\u5185\u5b58\u91cc\u5b58\u6307\u9488
        \n \u4e24\u4e2a\u8fdb\u7a0b\u7684\u865a\u62df\u5730\u5740\u4e0d\u540c，\u6307\u9488\u6beb\u65e0\u610f\u4e49
        \n \u2192 \u53ea\u80fd\u5b58\u504f\u79fb\u91cf（offset）<\/p>\n

        \u2461 \u4e0d\u80fd\u5b58 C++ \u5bf9\u8c61
        \n \u6709\u865a\u8868\u6307\u9488 \u2192 \u5c31\u662f\u6307\u9488\u95ee\u9898<\/p>\n

        \u2462 \u5bf9\u65b9\u8fdb\u7a0b\u5d29\u6e83\u65f6\u72b6\u6001\u672a\u5b9a\u4e49
        \n \u5f55\u5236\u8fdb\u7a0b\u6302\u4e86 \u2192 \u73af\u5f62\u7f13\u51b2\u4f1a\u586b\u6ee1 \u2192 \u751f\u4ea7\u8005\u5fc5\u987b\u80fd\u4f18\u96c5\u4e22\u5e27
        \n \u2192 \u9700\u8981\u5fc3\u8df3：\u5728\u5171\u4eab\u5185\u5b58\u91cc\u653e\u4e00\u4e2a heartbeat \u8ba1\u6570\u5668，
        \n \u6d88\u8d39\u8005\u5b9a\u671f ++，\u751f\u4ea7\u8005\u68c0\u6d4b\u8d85\u65f6\u540e\u505c\u6b62 push<\/p>\n

        \n

        \u7b2c 7 \u7ae0：\u600e\u4e48\u5ea6\u91cf<\/h2>\n

        7.1 \u770b\u6620\u5c04\u5168\u8c8c<\/h3>\n

        PID<\/span>=<\/span>$(<\/span>adb shell pidof com.xxx.game |<\/span> tr<\/span> -d<\/span> '\\\\r'<\/span>)<\/span><\/span><\/p>\n

        # \u6c47\u603b（\u6700\u5feb\u770b\u5168\u5c40）<\/span>
        \nadb shell run-as com.xxx.game cat<\/span> \/proc\/$PID<\/span>\/smaps_rollup<\/p>\n

        Rss: 742180 kB
        \nPss: 718240 kB
        \nShared_Clean: 58200 kB
        \nPrivate_Clean: 412300 kB \u2190 \u2605 \u53ef\u76f4\u63a5\u56de\u6536\u7684\u90e8\u5206，\u8d8a\u5927\u8d8a"\u6297\u6740"
        \nPrivate_Dirty: 271680 kB \u2190 \u2605 \u5fc5\u987b\u6740\u8fdb\u7a0b\u624d\u80fd\u91ca\u653e
        \nSwap: 0 kB<\/p>\n

        \u6838\u5fc3\u6307\u6807：Private_Clean \/ Private_Dirty \u7684\u6bd4\u503c\u3002 \u6bd4\u503c\u8d8a\u9ad8，\u4f60\u5728 LMK \u773c\u91cc\u8d8a\u5b89\u5168\u3002<\/p>\n

        7.2 \u770b Page Fault<\/h3>\n

        # $10 = minflt, $12 = majflt<\/span>
        \nadb shell cat<\/span> \/proc\/$PID<\/span>\/stat |<\/span> awk<\/span> '{print "minflt="$10, "majflt="$12}'<\/span><\/p>\n

        \u5224\u8bfb：<\/p>\n

          \n
        • minflt \u5927\u662f\u6b63\u5e38\u7684（\u9996\u6b21\u89e6\u78b0\u5df2\u7f13\u5b58\u7684\u9875）<\/li>\n
        • majflt \u5728\u6218\u6597\u4e2d\u6301\u7eed\u589e\u957f = \u6709\u95ee\u9898<\/li>\n<\/ul>\n

          7.3 \u770b\u5355\u4e2a\u6620\u5c04\u7684\u9a7b\u7559\u7387<\/h3>\n

          adb shell run-as com.xxx.game "grep -A 6 'base.pack' \/proc\/$PID<\/span>\/smaps"<\/span><\/p>\n

          Size: 820480 kB
          \nRss: 186240 kB \u2190 \u9a7b\u7559\u7387 22.7%<\/p>\n

          \u9a7b\u7559\u7387\u80fd\u544a\u8bc9\u4f60"\u9884\u70ed\u505a\u5f97\u591f\u4e0d\u591f"\u3002<\/p>\n

          7.4 \u6e38\u620f\u5185\u5b9e\u65f6\u76d1\u63a7<\/h3>\n

          public<\/span> class<\/span> FaultMonitor<\/span> :<\/span> MonoBehaviour<\/span><\/span>
          \n{<\/span>
          \n long<\/span><\/span> lastMaj;<\/span>
          \n void<\/span><\/span> Update<\/span>(<\/span>)<\/span> {<\/span>
          \n if<\/span> (<\/span>Time.<\/span>frameCount %<\/span> 60<\/span> !=<\/span> 0<\/span>)<\/span> return<\/span>;<\/span>
          \n long<\/span><\/span> maj =<\/span> ReadMajFlt<\/span>(<\/span>)<\/span>;<\/span>
          \n long<\/span><\/span> delta =<\/span> maj –<\/span> lastMaj;<\/span>
          \n lastMaj =<\/span> maj;<\/span><\/p>\n

          \/\/ \u2605 \u6218\u6597\u4e2d\u6bcf\u79d2 major fault \u8d85\u8fc7 100 \u2192 \u9884\u70ed\u7b56\u7565\u6709\u6f0f\u6d1e<\/span>
          \n if<\/span> (<\/span>BattleState.<\/span>InBattle &&<\/span> delta ><\/span> 100<\/span>)<\/span> {<\/span>
          \n Debug.<\/span>LogWarning<\/span>(<\/span>$"[MMAP] majflt burst: +<\/span>{<\/span>delta<\/span>}<\/span><\/span>\/s"<\/span><\/span>)<\/span>;<\/span>
          \n Breadcrumb.<\/span>Mark<\/span>(<\/span>Crumb.<\/span>MajorFaultBurst,<\/span> (<\/span>ushort<\/span>)<\/span>delta)<\/span>;<\/span>
          \n }<\/span>
          \n }<\/span><\/p>\n

          static<\/span> long<\/span><\/span> ReadMajFlt<\/span>(<\/span>)<\/span> {<\/span>
          \n try<\/span> {<\/span>
          \n var<\/span><\/span> f =<\/span> File.<\/span>ReadAllText<\/span>(<\/span>"\/proc\/self\/stat"<\/span>)<\/span>.<\/span>Split<\/span>(<\/span>' '<\/span>)<\/span>;<\/span>
          \n return<\/span> long<\/span>.<\/span>Parse<\/span>(<\/span>f[<\/span>11<\/span>]<\/span>)<\/span>;<\/span> \/\/ \u7b2c 12 \u4e2a\u5b57\u6bb5（0-based \u7d22\u5f15 11）<\/span>
          \n }<\/span> catch<\/span> {<\/span> return<\/span> 0<\/span>;<\/span> }<\/span>
          \n }<\/span>
          \n}<\/span><\/p>\n

          \n

          \u7b2c 8 \u7ae0：\u9677\u9631\u6e05\u5355<\/h2>\n\n\u9677\u9631\u75c7\u72b6\u89e3\u6cd5<\/tr>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
          \u672a ftruncate \u5c31 mmap<\/td>\nSIGBUS（\u4e0d\u662f SEGV，\u66f4\u96be\u67e5）<\/td>\nmmap \u524d\u5fc5\u987b\u5148\u8bbe\u7f6e\u6587\u4ef6\u5927\u5c0f<\/td>\n<\/tr>\n
          MAP_PRIVATE \u5199\u5165<\/td>\n\u5185\u5b58\u7ffb\u500d（COW），\u6587\u4ef6\u91cc\u4ec0\u4e48\u90fd\u6ca1\u6709<\/td>\n\u8981\u5199\u5c31\u7528 MAP_SHARED<\/td>\n<\/tr>\n
          \u53ea\u8bfb\u8d44\u6e90\u4e0d\u5c0f\u5fc3\u5199\u4e86<\/td>\nPSS \u6084\u6084\u6da8，anon \u9875\u589e\u52a0<\/td>\n\u7528 PROT_READ \u5f3a\u5236，\u5199\u5c31\u5d29\u6e83\u66b4\u9732\u95ee\u9898<\/td>\n<\/tr>\n
          offset \u672a\u9875\u5bf9\u9f50<\/td>\nmmap \u8fd4\u56de EINVAL<\/td>\noffset \u5bf9\u9f50\u5230 sysconf(_SC_PAGESIZE)<\/td>\n<\/tr>\n
          APK \u5185\u6761\u76ee\u88ab\u538b\u7f29<\/td>\nLoadFromFile \u9000\u5316\u4e3a\u5168\u91cf\u89e3\u538b<\/td>\ngradle noCompress \u914d\u7f6e<\/td>\n<\/tr>\n
          \u6218\u6597\u4e2d major fault \u98ce\u66b4<\/td>\n\u968f\u673a 40~90ms \u5361\u987f，Profiler \u770b\u4e0d\u51fa<\/td>\n\u52a0\u8f7d\u671f posix_fadvise \u9884\u70ed<\/td>\n<\/tr>\n
          \u5207\u540e\u53f0\u518d\u56de\u6765\u5361<\/td>\n\u9875\u88ab\u56de\u6536，\u91cd\u65b0 fault<\/td>\n\u56de\u524d\u53f0\u65f6\u540e\u53f0\u7ebf\u7a0b\u91cd\u65b0\u9884\u70ed<\/td>\n<\/tr>\n
          mlock \u60f3\u9489\u4f4f\u9875<\/td>\n\u53cd\u800c\u66f4\u5bb9\u6613\u88ab LMK \u6574\u4f53\u6740\u6389<\/td>\n\u7528 MADV_WILLNEED \u4ee3\u66ff<\/td>\n<\/tr>\n
          \u5916\u90e8\u5b58\u50a8 mmap<\/td>\nfault \u6210\u672c 2~5 \u500d<\/td>\n\u70ed\u6570\u636e\u5fc5\u987b\u653e \/data \u5185\u90e8\u5b58\u50a8<\/td>\n<\/tr>\n
          \u5171\u4eab\u5185\u5b58\u5b58\u6307\u9488<\/td>\n\u53e6\u4e00\u8fdb\u7a0b\u89e3\u5f15\u7528\u5d29\u6e83<\/td>\n\u53ea\u5b58\u504f\u79fb\u91cf<\/td>\n<\/tr>\n
          \u5c0f\u6587\u4ef6 mmap<\/td>\n\u6bd4 read \u8fd8\u6162<\/td>\n< 64KB \u7684\u6587\u4ef6\u76f4\u63a5 read<\/td>\n<\/tr>\n
          VMA \u6570\u91cf\u7206\u70b8<\/td>\nfault \u53d8\u6162，\/proc\/pid\/maps \u51e0\u5343\u884c<\/td>\n\u5408\u5e76\u6210\u5927 pack + offset<\/td>\n<\/tr>\n
          msync(MS_SYNC) \u6bcf\u6b21\u8c03<\/td>\n\u53d8\u6210\u540c\u6b65 IO，\u5361\u7206<\/td>\n\u7528 MS_ASYNC，\u53ea\u5728\u5173\u952e\u70b9\u7528 SYNC<\/td>\n<\/tr>\n
          \u5fd8\u8bb0 munmap<\/td>\n\u865a\u62df\u5730\u5740\u7a7a\u95f4\u8017\u5c3d（32 \u4f4d\u5c24\u5176）<\/td>\n\u914d\u5bf9\u91ca\u653e；64 \u4f4d\u95ee\u9898\u5c0f\u4f46\u4ecd\u8981\u7ba1<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
          \n

          \u7ed3\u8bed<\/h2>\n

          \u56de\u5230\u6807\u9898\u90a3\u53e5\u8bdd，\u73b0\u5728\u53ef\u4ee5\u5b8c\u6574\u89e3\u91ca\u4e86：<\/p>\n

          \u201c\u8ba9\u7528\u6237\u7a7a\u95f4\u7684\u4e00\u6bb5\u865a\u62df\u5730\u5740\u76f4\u63a5\u6307\u5411\u5185\u6838\u7684 page cache\u201d<\/p>\n

          = \u5185\u6838\u5728\u4f60\u7684\u9875\u8868\u9879（PTE）\u91cc，\u5199\u5165\u4e86 page cache \u90a3\u4e2a struct page \u7684\u7269\u7406\u9875\u5e27\u53f7\u3002<\/p>\n

          \u6ca1\u6709\u62f7\u8d1d，\u53ea\u6709\u4e00\u6b21\u9875\u8868\u5199\u5165\u3002
          \n\u4ece\u6b64\u4f60\u7684\u865a\u62df\u5730\u5740\u548c\u5185\u6838\u7684 page cache \u7d22\u5f15，\u6307\u5411\u540c\u4e00\u5757\u7269\u7406\u5185\u5b58\u3002<\/p>\n

          \u8fd9\u4e2a\u673a\u5236\u5e26\u6765\u4e09\u4e2a\u5c42\u6b21\u7684\u4ef7\u503c，\u4e5f\u5e26\u6765\u4e09\u4e2a\u5c42\u6b21\u7684\u4ee3\u4ef7：<\/p>\n\n\u5c42\u6b21\u6536\u76ca\u4ee3\u4ef7<\/tr>\n\n\n\n\n
          \u5185\u5b58<\/td>\n\u53ea\u6709\u8bbf\u95ee\u8fc7\u7684\u9875\u624d\u9a7b\u7559，PSS \u964d 10 \u500d<\/td>\n\u865a\u62df\u5730\u5740\u7a7a\u95f4\u5360\u6ee1，VMA \u589e\u591a<\/td>\n<\/tr>\n
          \u901f\u5ea6<\/td>\n\u52a0\u8f7d = \u5efa VMA，\u5fae\u79d2\u7ea7<\/td>\n\u6210\u672c\u63a8\u8fdf\u5230 page fault，\u65f6\u673a\u4e0d\u53ef\u63a7<\/td>\n<\/tr>\n
          \u53ef\u9760\u6027<\/td>\n\u810f\u9875\u5f52\u5185\u6838，SIGKILL \u4e5f\u4e0d\u4e22<\/td>\n\u5199\u56de\u65f6\u673a\u4e0d\u786e\u5b9a，\u9700\u8981 msync \u515c\u5e95<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

          \u6700\u91cd\u8981\u7684\u4e00\u8bfe，\u6765\u81ea\u6848\u4f8b 2：<\/p>\n

          mmap \u4e0d\u662f"\u96f6\u6210\u672c"，\u800c\u662f"\u628a\u6210\u672c\u4ece\u4e00\u6b21\u96c6\u4e2d\u7684\u5927\u62f7\u8d1d，\u6362\u6210\u5206\u6563\u7684\u3001\u4e0d\u53ef\u9884\u6d4b\u7684 page fault"\u3002<\/p>\n

          \u5728\u52a0\u8f7d\u754c\u9762，\u5206\u6563\u7684 fault \u662f\u597d\u4e8b（\u5185\u5b58\u4f4e\u3001\u542f\u52a8\u5feb）\u3002
          \n\u5728\u6218\u6597\u4e2d，\u4e0d\u53ef\u9884\u6d4b\u7684 fault \u662f\u707e\u96be（\u5361\u987f\u65e0\u6cd5\u5f52\u56e0）\u3002<\/p>\n

          \u6240\u4ee5\u771f\u6b63\u7684\u5de5\u7a0b\u89e3\u6cd5\u4ece\u6765\u4e0d\u662f"\u7528 mmap"，\u800c\u662f：
          \n\u7528 mmap \u6362\u5185\u5b58，\u7528\u9884\u70ed\u6362\u786e\u5b9a\u6027，\u7528 Private_Clean \u6362\u6d3b\u547d\u673a\u4f1a\u3002<\/p>\n

          \u5982\u679c\u4f60\u7684\u5c04\u51fb\u9879\u76ee\u53ea\u505a\u4e00\u4ef6\u4e8b，\u5c31\u505a\u8fd9\u4e2a：<\/p>\n

          LoadFromFile \u4e4b\u524d，\u5148\u5728\u540e\u53f0\u7ebf\u7a0b posix_fadvise(WILLNEED) \u628a\u672c\u5c40\u8d44\u6e90\u6572\u8fdb page cache\u3002 \u4e00\u4e2a\u51e0\u5341\u884c\u7684\u539f\u751f\u63d2\u4ef6，\u80fd\u628a\u6218\u6597\u5361\u987f P99 \u4ece 47ms \u964d\u5230 11ms\u3002<\/p>\n

          \n

          \u53c2\u8003\u8d44\u6e90<\/h4>\n

          \u5185\u6838\u673a\u5236<\/p>\n

            \n
          • Linux man pages \u2014 mmap(2)\u3001madvise(2)\u3001posix_fadvise(2)\u3001msync(2)\u3001mincore(2)\u3001mlock(2)<\/li>\n
          • Linux Kernel Docs \u2014 Memory Management（vm_area_struct\u3001address_space\u3001page cache \u4e0e XArray）<\/li>\n
          • \u5185\u6838\u6e90\u7801\u8def\u5f84 \u2014 mm\/filemap.c: filemap_fault()\u3001mm\/memory.c: handle_mm_fault() \/ do_fault_around() \/ do_wp_page()<\/li>\n
          • LWN.net \u2014 Fault-around\u3001Page reclaim and the LRU lists\u3001Transparent huge pages<\/li>\n
          • Mel Gorman \u2014 Understanding the Linux Virtual Memory Manager<\/li>\n<\/ul>\n

            Android \u5e73\u53f0<\/p>\n

              \n
            • Android Developers \u2014 Memory allocation among processes\u3001Process importance & LMK<\/li>\n
            • Android NDK \u2014 ASharedMemory\u3001AHardwareBuffer<\/li>\n
            • Android \u2014 Support 16 KB page sizes（Android 15 arm64 \u5bf9\u9f50\u8981\u6c42）<\/li>\n
            • \/proc\/<pid>\/smaps\u3001smaps_rollup\u3001stat（minflt\/majflt）\u5b57\u6bb5\u8bf4\u660e<\/li>\n
            • zipalign \u4e0e APK \u5185 STORED \u6761\u76ee\u53ef mmap \u7684\u524d\u63d0<\/li>\n<\/ul>\n

              Unity<\/p>\n

                \n
              • Unity Manual \u2014 AssetBundle compression（Uncompressed \/ LZ4 \/ LZMA \u7684\u52a0\u8f7d\u884c\u4e3a\u5dee\u5f02）<\/li>\n
              • Unity Scripting API \u2014 AssetBundle.LoadFromFile(path, crc, offset)<\/li>\n
              • Unity Manual \u2014 Android: Split Application Binary\u3001gradle noCompress \u914d\u7f6e<\/li>\n<\/ul>\n

                \u6027\u80fd\u6d4b\u91cf<\/p>\n

                  \n
                • Perfetto \u2014 \u7cfb\u7edf\u7ea7 tracing，\u53ef\u89c2\u5bdf page fault \u4e0e IO \u963b\u585e<\/li>\n
                • Android simpleperf \u2014 CPU \u91c7\u6837（\u6ce8\u610f：\u7761\u7720\u7b49 IO \u7684\u65f6\u95f4\u91c7\u6837\u5668\u770b\u4e0d\u5230）<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"

                  mmap \u7684\u5e95\u5c42\u771f\u76f8，\u4ee5\u53ca\u5c04\u51fb\u6e38\u620f\u91cc\u7684\u6bcf\u4e00\u6b21\u4ee3\u4ef7\u7b2c 0 \u7ae0：\u5148\u5efa\u7acb\u76f4\u89c9
                  \n0.1 \u4e00\u4e2a\u6bd4\u55bb：\u540c\u4e00\u672c\u4e66，\u4e24\u4e2a\u95e8\u724c\u53f7
                  \n\u56fe\u4e66\u9986\u6709\u4e00\u672c\u4e66，\u7f16\u53f7 \u7269\u7406\u4e66\u67b6 P7\u3002
                  \n\u8bfb\u8005 A \u7684\u501f\u4e66\u5355\u4e0a\u5199\u7740：\\”\u7b2c 3 \u53f7\u9605\u89c8\u684c\\”
                  \n\u8bfb\u8005 B \u7684\u501f\u4e66\u5355\u4e0a\u5199\u7740：\\”\u7b2c 9 \u53f7\u9605\u89c8\u684c\\”
                  \n\u56fe\u4e66\u9986\u7ba1\u7406\u7cfb\u7edf\u91cc\u8bb0\u7740： \\”\u7269\u7406\u4e66\u67b6 P7\\”\u4e09\u4e2a\u4e0d\u540c\u7684\\”\u5730\u5740\\”，\u6307\u5411\u540c\u4e00\u672c\u4e66\u3002\u8fd9\u5c31\u662f\u865a\u62df\u5185\u5b58：<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[11786],"topic":[],"class_list":["post-103374","post","type-post","status-publish","format-standard","hentry","category-server","tag-mmap"],"yoast_head":"\nmmap\u7684\u771f\u76f8\uff1a\u4e0d\u62f7\u8d1d\uff0c\u53ea\u6620\u5c04 - \u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.wsisp.com\/helps\/103374.html\" \/>\n<meta property=\"og:locale\" content=\"zh_CN\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"mmap\u7684\u771f\u76f8\uff1a\u4e0d\u62f7\u8d1d\uff0c\u53ea\u6620\u5c04 - 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