{"id":806,"date":"2019-09-26T13:38:28","date_gmt":"2019-09-26T05:38:28","guid":{"rendered":"http:\/\/149.129.74.185\/?p=806"},"modified":"2019-09-26T15:36:06","modified_gmt":"2019-09-26T07:36:06","slug":"%e6%93%8d%e4%bd%9c%e7%b3%bb%e7%bb%9fweek-3-note","status":"publish","type":"post","link":"http:\/\/www.magicmipamipa.com\/?p=806","title":{"rendered":"[\u64cd\u4f5c\u7cfb\u7edf]Week 3 Note"},"content":{"rendered":"

\u7ebf\u7a0b Threads<\/span><\/h1>\n

\u4e00\u3001\u6982\u8ff0<\/span><\/strong><\/p>\n

MEMO:\u8fdb\u7a0b\u548c\u7ebf\u7a0b\u6709\u4ec0\u4e48\u533a\u522b\uff1f<\/p><\/blockquote>\n

\u8fdb\u7a0b(Process)\u7684\u4e24\u4e2a\u7279\u6027\uff1a<\/p>\n

Unit of Resource ownership \uff08\u8d44\u6e90\u62e5\u6709\u5355\u4f4d\uff09<\/p>\n

    \n
  • \u7ed9\u6bcf\u4e2a\u8fdb\u7a0b\u5206\u914d\u4e00\u865a\u62df\u5730\u5740\u7a7a\u95f4\uff0c\u4fdd\u5b58\u8fdb\u7a0b\u6620\u50cf\uff0c\u63a7\u5236\u4e00\u4e9b\u8d44\u6e90\uff08\u6587\u4ef6\uff0c I\/O\u8bbe\u5907\uff09<\/li>\n
  • \u6709\u72b6\u6001\u3001\u4f18\u5148\u7ea7\u3001\u8c03\u5ea6<\/li>\n<\/ul>\n

    Unit of Dispatching \uff08\u8c03\u5ea6\u5355\u4f4d\uff09<\/p>\n

      \n
    • \u8fdb\u7a0b\u662f\u7531\u4e00\u4e2a\u6216\u591a\u4e2a\u7a0b\u5e8f\u7684\u4e00\u6b21\u6267\u884c<\/li>\n
    • \u53ef\u80fd\u4f1a\u4e0e\u5176\u4ed6\u8fdb\u7a0b\u4ea4\u66ff\u6267\u884c<\/li>\n<\/ul>\n

      \u7ebf\u7a0b<\/strong>(Thread)\uff1a \u8fdb\u7a0b\u5185\u4e00\u4e2a\u6267\u884c\u5355\u5143<\/span><\/span>\u6216\u4e00\u4e2a\u53ef\u8c03\u5ea6\u5b9e\u4f53<\/span><\/span>\u3002<\/strong><\/span><\/p>\n

      \u8d44\u6e90\u62e5\u6709\u5355\u5143\u79f0\u4e3a\u8fdb\u7a0b\uff08\u6216\u4efb\u52a1\uff09\uff0c\u8c03\u5ea6\u7684\u5355\u4f4d\u79f0\u4e3a\u7ebf\u7a0b\u3001\u53c8\u79f0\u8f7b\u578b\u8fdb\u7a0b\uff08 light weight process\uff09\u3002<\/p>\n

      \u7ebf\u7a0b\u53ea\u62e5\u6709\u4e00\u70b9\u5728\u8fd0\u884c\u4e2d\u5fc5\u4e0d\u53ef\u7701\u7684\u8d44\u6e90<\/span>\uff08\u7a0b\u5e8f\u8ba1\u6570\u5668\u3001\u4e00\u7ec4\u5bc4\u5b58\u5668\u548c\u6808\uff09 \uff0c\u4f46\u5b83\u53ef\u4e0e\u540c\u5c5e\u4e00\u4e2a\u8fdb\u7a0b\u7684\u5176\u5b83\u7ebf\u7a0b\u5171\u4eab\u8fdb\u7a0b\u62e5\u6709\u7684\u5168\u90e8\u8d44\u6e90\u3002 \uff08\u62e5\u6709\u5c11\u91cf\u8d44\u6e90\uff0c\u5171\u4eab\u8fdb\u7a0b\u7684\u5168\u90e8\u8d44\u6e90\uff09<\/em><\/p>\n

        \n
      • \u4e0d\u62e5\u6709\u7cfb\u7edf\u8d44\u6e90\uff08\u53ea\u62e5\u6709\u5c11\u91cf\u7684\u8d44\u6e90\uff0c\u8d44\u6e90\u662f\u5206\u914d\u7ed9\u8fdb\u7a0b\uff09<\/li>\n
      • \u4e00\u4e2a\u8fdb\u7a0b\u4e2d\u7684\u591a\u4e2a\u7ebf\u7a0b\u53ef\u5e76\u53d1\u6267\u884c\uff08\u8fdb\u7a0b\u53ef\u521b\u5efa\u7ebf\u7a0b\u6267\u884c\u540c\u4e00\u7a0b\u5e8f\u7684\u4e0d\u540c\u90e8\u5206\uff09<\/li>\n
      • \u7cfb\u7edf\u5f00\u9500\u5c0f\u3001\u5207\u6362\u5feb\u3002\uff08\u8fdb\u7a0b\u7684\u591a\u4e2a\u7ebf\u7a0b\u90fd\u5728\u8fdb\u7a0b\u7684\u5730\u5740\u7a7a\u95f4\u6d3b\u52a8\uff09<\/li>\n<\/ul>\n
        \n
          \n
        • \u6709\u6267\u884c\u72b6\u6001\uff08\u72b6\u6001\u8f6c\u6362\uff09<\/span><\/li>\n
        • \u4e0d\u8fd0\u884c\u65f6\u4fdd\u5b58\u4e0a\u4e0b\u6587 <\/span><\/li>\n
        • \u6709\u4e00\u4e2a\u6267\u884c\u6808 <\/span><\/li>\n
        • \u6709\u4e00\u4e9b\u5c40\u90e8\u53d8\u91cf\u7684\u9759\u6001\u5b58\u50a8 <\/span><\/li>\n
        • \u53ef\u5b58\u53d6\u6240\u5728\u8fdb\u7a0b\u7684\u5185\u5b58\u548c\u5176\u4ed6\u8d44\u6e90<\/span><\/li>\n
        • \u53ef\u4ee5\u521b\u5efa\u3001\u64a4\u6d88\u53e6\u4e00\u4e2a\u7ebf\u7a0b<\/span><\/li>\n<\/ul>\n<\/blockquote>\n

          <\/p>\n

          \u5355\u7ebf\u7a0b\u4e0e\u591a\u7ebf\u7a0b\u8fdb\u7a0b<\/p>\n

          \u4e8c\u3001\u591a\u7ebf\u7a0b\u6a21\u578b<\/span><\/strong><\/p>\n

          1.\u7528\u6237\u7ea7\u7ebf\u7a0b user-level thread<\/p>\n

          \u7528\u6237\u7ea7\u7ebf\u7a0b\uff1a\u4e0d\u4f9d\u8d56\u4e8eOS\u6838\u5fc3\uff08\u5185\u6838\u4e0d\u4e86\u89e3\u7528\u6237\u7ebf\u7a0b\u7684\u5b58\u5728\uff09\uff0c\u5e94\u7528\u8fdb\u7a0b\u5229\u7528\u7ebf\u7a0b\u5e93\u63d0\u4f9b\u521b\u5efa\u3001\u540c\u6b65\u3001\u8c03\u5ea6\u548c\u7ba1\u7406\u7ebf\u7a0b\u7684\u51fd\u6570\u6765\u63a7\u5236\u7528\u6237\u7ebf\u7a0b\u3002<\/p>\n

          \u5982\uff1a\u6570\u636e\u5e93\u7cfb\u7edfinformix\uff0c\u56fe\u5f62\u5904\u7406Aldus PageMaker\u3002\u8c03\u5ea6\u7531\u5e94\u7528\u8f6f\u4ef6\u5185\u90e8\u8fdb\u884c\uff0c\u901a\u5e38\u91c7\u7528\u975e\u62a2\u5148\u5f0f\u548c\u66f4\u7b80\u5355\u7684\u89c4\u5219\uff0c\u4e5f\u65e0\u9700\u7528\u6237\u6001\/\u6838\u5fc3\u6001\u5207\u6362\uff0c\u6240\u4ee5\u901f\u5ea6\u7279\u522b\u5feb\u3002\u4e00\u4e2a\u7ebf\u7a0b\u53d1\u8d77\u7cfb\u7edf\u8c03\u7528\u800c\u963b\u585e\uff0c\u5219\u6574\u4e2a\u8fdb\u7a0b\u5728\u7b49\u5f85\u3002<\/p>\n

            \n
          • \u7528\u6237\u7ebf\u7a0b\u7684\u7ef4\u62a4\u7531\u5e94\u7528\u8fdb\u7a0b\u5b8c\u6210\uff1b<\/li>\n
          • \u5185\u6838\u4e0d\u4e86\u89e3\u7528\u6237\u7ebf\u7a0b\u7684\u5b58\u5728\uff1b<\/li>\n
          • \u7528\u6237\u7ebf\u7a0b\u5207\u6362\u4e0d\u9700\u8981\u5185\u6838\u7279\u6743\uff1b<\/li>\n
          • \u7528\u6237\u7ebf\u7a0b\u8c03\u5ea6\u7b97\u6cd5\u53ef\u9488\u5bf9\u5e94\u7528\u4f18\u5316\uff1b<\/li>\n
          • \u4e00\u4e2a\u7ebf\u7a0b\u53d1\u8d77\u7cfb\u7edf\u8c03\u7528\u800c\u963b\u585e\uff0c\u5219\u6574\u4e2a\u8fdb\u7a0b\u5728\u7b49\u5f85\u3002\uff08\u4e00\u5bf9\u591a\u6a21\u578b\u4e2d\uff09<\/li>\n<\/ul>\n

            Three primary thread libraries: POSIX Pthreads \u3001 Win32 threads\u3001 Java threads<\/p>\n

            2.\u5185\u6838\u7ea7\u7ebf\u7a0b kernel-level thread<\/p>\n

            \u5185\u6838\u7ea7\u7ebf\u7a0b\uff1a\u4f9d\u8d56\u4e8eOS\u6838\u5fc3\uff0c\u7531\u5185\u6838\u7684\u5185\u90e8\u9700\u6c42\u8fdb\u884c\u521b\u5efa\u548c\u64a4\u9500\uff0c\u7528\u6765\u6267\u884c\u4e00\u4e2a\u6307\u5b9a\u7684\u51fd\u6570\u3002\u4e00\u4e2a\u7ebf\u7a0b\u53d1\u8d77\u7cfb\u7edf\u8c03\u7528\u800c\u963b\u585e\uff0c\u4e0d\u4f1a\u5f71\u54cd\u5176\u4ed6\u7ebf\u7a0b\u3002\u65f6\u95f4\u7247\u5206\u914d \u7ed9\u7ebf\u7a0b\uff0c\u6240\u4ee5\u591a\u7ebf\u7a0b\u7684\u8fdb\u7a0b\u83b7\u5f97\u66f4\u591aCPU\u65f6\u95f4\u3002<\/p>\n

              \n
            • \u5185\u6838\u7ef4\u62a4\u8fdb\u7a0b\u548c\u7ebf\u7a0b\u7684\u4e0a\u4e0b\u6587\u4fe1\u606f\uff1b<\/li>\n
            • \u7ebf\u7a0b\u5207\u6362\u7531\u5185\u6838\u5b8c\u6210\uff1b<\/li>\n
            • \u65f6\u95f4\u7247\u5206\u914d\u7ed9\u7ebf\u7a0b\uff0c\u6240\u4ee5\u591a\u7ebf\u7a0b\u7684\u8fdb\u7a0b\u83b7\u5f97\u66f4\u591aCPU\u65f6\u95f4\uff1b<\/li>\n
            • \u4e00\u4e2a\u7ebf\u7a0b\u53d1\u8d77\u7cfb\u7edf\u8c03\u7528\u800c\u963b\u585e\uff0c\u4e0d\u4f1a\u5f71\u54cd\u5176\u4ed6\u7ebf\u7a0b\u7684\u8fd0\u884c\u3002<\/li>\n<\/ul>\n

              Examples \uff1aWindows XP\/2000 \u53ca\u4ee5\u540e\u3001Solaris\u3001Linux\u3001POSIX Pthreads\u3001Mac OS X<\/p>\n

              3.\u591a\u5bf9\u4e00\u6a21\u578b Many-to-One<\/p>\n

              4.\u4e00\u5bf9\u4e00\u6a21\u578b One-to-One<\/p>\n

              EG:Windows NT\/XP\/2000\u3001Linux\u3001Solaris 9 and later<\/p>\n

              5.\u4e00\u5bf9\u591a\u6a21\u578b One-to-Many<\/p>\n

              EG:IRIX\u3001HP-UX\u3001Solaris 9 before<\/p>\n

               <\/p>\n

              \u4e09\u3001\u7ebf\u7a0b\u5e93<\/span><\/strong><\/p>\n

              1.Pthread<\/p>\n

              POSIX\u6807\u51c6\u4e3a\u7ebf\u7a0b\u521b\u5efa\u548c\u540c\u6b65\u5b9a\u4e49\u7684API<\/p>\n

              2.Java\u7ebf\u7a0b<\/p>\n

              JVM<\/p>\n

              3.Implicit Threading \u9690\u85cf\u591a\u7ebf\u7a0b<\/p>\n

              \u591a\u6838\u7cfb\u7edf\u591a\u7ebf\u7a0b\u7f16\u7a0b\uff0c\u4e00\u4e2a\u5e94\u7528\u7a0b\u5e8f\u6709\u53ef\u80fd\u6709\u51e0\u767e\u4e2a\u751a\u81f3\u4e0a\u5343\u7684\u7ebf\u7a0b\uff0c\u8fd9\u6837\u7684\u7a0b\u5e8f\u9762\u4e34\u8bb8\u591a\u6311\u6218<\/span><\/strong>\uff1a<\/p>\n

              \u7f16\u7a0b\u6311\u6218\uff1a\u4efb\u52a1\u5206\u89e3\u3001\u4efb\u52a1\u7684\u5de5\u4f5c\u91cf\u5e73\u8861\u3001\u6570\u636e\u5206\u5272\u3001\u6570\u636e\u4f9d\u8d56\u3001\u6d4b\u8bd5\u4e0e\u8c03\u8bd5<\/p>\n

              \u7a0b\u5e8f\u6267\u884c\u987a\u5e8f\u7684\u6b63\u786e\u6027\u95ee\u9898\uff1a\u540c\u6b65\u3001\u4e92\u65a5<\/p>\n

              \u7b56\u7565<\/span><\/strong><\/span>\uff1a\u9690\u79c1\u7ebf\u7a0bImplicit Threading\uff0c\u5f53\u524d\u4e00\u79cd\u6d41\u884c\u8d8b\u52bf\u3002<\/p>\n

              \u5c06\u7ebf\u7a0b\u7684\u521b\u5efa\u4e0e\u7ba1\u7406\u4ea4\u7ed9\u7f16\u8bd1\u5668<\/strong><\/span>\u548c\u8fd0\u884c\u65f6\u5e93<\/strong><\/span>\u6765\u5b8c\u6210<\/p>\n

              \u51e0\u79cd\u9690\u79c1\u7ebf\u7a0b\u7684\u8bbe\u8ba1\u65b9\u6cd5\uff1a<\/p>\n

                \n
              • Thread Pools<\/span>\uff08\u7ebf\u7a0b\u6c60\uff09<\/li>\n
              • Fork Join<\/span><\/li>\n
              • OpenMP<\/span>\uff0c\u7528\u4e8e\u5171\u4eab\u5185\u5b58\u5e76\u884c\u7cfb\u7edf\u7684\u591a\u5904\u7406\u5668\u7a0b\u5e8f\u8bbe\u8ba1\u7684\u4e00\u5957\u6307\u5bfc\u6027\u7f16\u8bd1\u5904\u7406\u65b9\u6848\u3002OpenMP\u652f\u6301\u7684\u7f16\u7a0b\u8bed\u8a00\u5305\u62ecC\u3001C++\u548cFortran\u3002<\/li>\n
              • Grand Central Dispatch<\/span>\uff08GCD\uff0c\u5927\u4e2d\u592e\u8c03\u5ea6\uff09\uff0cApple for its macOS and iOS operating systems.<\/li>\n
              • Intel Thread Building Blocks<\/span>\uff08TBB\uff09\uff0cIntel\u5f00\u53d1\u7684\u6784\u5efa\u591a\u7ebf\u7a0b\u5e93\uff0copen source \uff1bTBB\u662f\u4e00\u4e2a\u53ef\u79fb\u690d\u7684C++\u5e93\uff0c\u80fd\u591f\u8fd0\u884c\u5728Windows\u3001Linux\u3001Macintosh\u4ee5\u53caUNIX\u7b49\u7cfb\u7edf\u4e0a \u3002<\/li>\n
              • Java<\/li>\n<\/ul>\n
                \n

                1.\u8fdb\u7a0b\u548c\u7a0b\u5e8f\u7684\u533a\u522b\uff1a\u8fdb\u7a0b\u6709\u72b6\u6001\uff0c\u7a0b\u5e8f\u6ca1\u6709\u72b6\u6001\u3002<\/p>\n

                2.\u8fdb\u7a0b\u8c03\u5ea6\u662f\u628a\u5b83\u7684\u72b6\u6001\u6539\u53d8\uff1aReady and Running<\/span>\uff08\u4ece\u51c6\u5907\u5230\u8fd0\u884c\uff09<\/p>\n

                3.\u5b50\u8fdb\u7a0b\u4e0d\u4f1a\u7ee7\u627f\u7236\u8fdb\u7a0b\u7684\u4ec0\u4e48\uff1aprocess ID<\/span><\/p>\n

                4.TCB\uff08\u7ebf\u7a0b\u63a7\u5236\u5757\uff09\u5b58\u50a8\uff1aThe machine state<\/span>\uff08\u5bc4\u5b58\u5668\u3001\u7a0b\u5e8f\u8ba1\u6570\u5668\uff09<\/p>\n

                5.\u591a\u5bf9\u4e00\u6a21\u578b\u4e2d\uff0c\u5982\u679c\u4e00\u4e2a\u7ebf\u7a0bblock\u4e86\uff0c\u6574\u4e2a\u8fdb\u7a0b\u90fd\u4f1ablock<\/p>\n

                6.\u82e5\u4e00\u4e2a\u7528\u6237\u8fdb\u7a0b\u901a\u8fc7read\u7cfb\u7edf\u8c03\u7528\u8bfb\u53d6\u4e00\u4e2a\u78c1\u76d8\u7684\u6570\u636e\uff1aa\u3001b<\/span><\/p>\n

                a.\u82e5\u8be5\u6587\u4ef6\u7684\u6570\u636e\u4e0d\u5728\u5185\u5b58\u3001\u5219\u8be5\u8fdb\u7a0b\u8fdb\u5165\u7b49\u5f85\u72b6\u6001\uff08\u78c1\u76d8\u8fd0\u884c\u8bfb\u53d6\uff0cCPU\u4e0d\u5de5\u4f5c<\/span>\uff09<\/p>\n

                b.\u8bf7\u6c42read\u7cfb\u7edf\u8c03\u7528\u4f1a\u5bfc\u81f4CPU\u4ece\u7528\u6237\u6001\u5207\u6362\u5230\u6838\u5fc3\u6001<\/p>\n

                c.read\u7cfb\u7edf\u8c03\u7528\u7684\u53c2\u6570\u5e94\u5305\u542b\u6587\u4ef6\u7684\u540d\u79f0\ud83d\ude45\u00a0<\/del> \u6587\u4ef6\u7684\u533a\u540d<\/span><\/p>\n

                \u00a07.\u4e0d\u7ba1\u7cfb\u7edf\u662f\u5426\u652f\u6301\u7ebf\u7a0b\uff0c\u8fdb\u7a0b\u90fd\u662f\u8d44\u6e90\u5206\u914d\u7684\u57fa\u672c\u5355\u4f4d<\/p>\n

                \u7528\u6237\u7ea7\u7ebf\u7a0b\u4e0d\u9700\u8981\u5185\u6838\u7684\u652f\u6301\uff08\u5185\u6838\u4e0d\u4e86\u89e3\u7528\u6237\u7ebf\u7a0b\u7684\u5b58\u5728\uff09<\/p>\n

                8.\u4e0b\u5217\u9009\u9879\u4e2d\u4f1a\u5bfc\u81f4\u8fdb\u7a0b\u4ece\u6267\u884c\u6001\u53d8\u4e3a\u5c31\u7eea\u6001\u7684\u4e8b\u4ef6\u662f D<\/span><\/p>\n

                A\u3001\u6267\u884cP\uff08wait\uff09\u64cd\u4f5c\u00a0 \u00a0 B\u3001\u7533\u8bf7\u5185\u5b58\u5931\u8d25<\/p>\n

                C\u3001\u542f\u52a8I\/O\u8bbe\u5907\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 D\u3001\u88ab\u9ad8\u4f18\u5148\u7ea7\u7684\u8fdb\u7a0b\u62a2\u5360<\/p>\n

                9.\u64cd\u4f5c\u7cfb\u7edf\u4e2d\u63d0\u4f9b\u4e86\u4e00\u79cd\u8fdb\u7a0b\u95f4\u7684\u901a\u4fe1\u673a\u5236\uff0c\u628a\u4e00\u4e2a\u8fdb\u7a0b\u7684\u6807\u51c6\u8f93\u51fa\u548c\u53e6\u4e00\u4e2a\u6807\u51c6\u8f93\u5165\u8fde\u63a5\u8d77\u6765\uff0c\u8fd9\u79cd\u673a\u5236\u79f0\u4e3a\u7ba1\u9053<\/span><\/p>\n

                \n

                CPU\u8c03\u5ea6<\/h2>\n

                \u4e00\u3001Basic Concepts \u57fa\u672c\u6982\u5ff5<\/span><\/p>\n

                CPU\u8c03\u5ea6\uff08CPU scheduling\uff09 = \u5904\u7406\u673a\u8c03\u5ea6 = \u8fdb\u7a0b\u8c03\u5ea6\uff08Process scheduling\uff09<\/p>\n

                \u5185\u5bb9\uff1a\u9009\u62e9\u4e00\u4e2a\u8fdb\u7a0b\u5206\u914d\u7ed9CPU\u8fd0\u884c\u00a0<\/span><\/strong><\/p>\n

                CPU scheduling decisions may take place when a process\uff08\u8c03\u5ea6\u7684\u65f6\u673a\uff09:<\/p>\n

                1. Switches from running to waiting state.\u4ece\u8fd0\u884c\u5230\u7b49\u5f85<\/p>\n

                2.Switches from running to ready state.\u4ece\u8fd0\u884c\u5230\u5c31\u7eea<\/p>\n

                3.Switches from waiting to ready.\u4ece\u7b49\u5f85\u5230\u5c31\u7eea<\/p>\n

                4.Terminates.\u7ec8\u6b62<\/p>\n

                \u4e24\u79cd\u8c03\u5ea6\u65b9\u5f0f\uff1a<\/p>\n

                \u975e\u62a2\u5360\u5f0f\uff08Nonpreemptive\uff09\u8c03\u5ea6:\u8c03\u5ea6\u7a0b\u5e8f\u4e00\u65e6\u628a\u5904\u7406\u673a\u5206\u914d\u7ed9\u67d0\u8fdb\u7a0b\u540e\u4fbf\u8ba9\u5b83\u4e00\u76f4\u8fd0 \u884c\u4e0b\u53bb\uff0c\u76f4\u5230\u8fdb\u7a0b\u5b8c\u6210\u6216\u53d1\u751f\u67d0\u4e8b\u4ef6\u800c\u963b\u585e\u65f6\uff0c\u624d\u628a\u5904\u7406\u673a\u5206\u914d\u7ed9\u53e6\u4e00\u4e2a\u8fdb\u7a0b\u3002\u5982\u4e0a1 \u30014<\/p>\n

                \u62a2\u5360\u5f0f\uff08Preemptive\uff09\u8c03\u5ea6:\u5f53\u4e00\u4e2a\u8fdb\u7a0b\u6b63\u5728\u8fd0\u884c\u65f6\uff0c\u7cfb\u7edf\u53ef\u4ee5\u57fa\u4e8e\u67d0\u79cd\u539f\u5219\uff0c\u5265\u593a\u5df2 \u5206\u914d\u7ed9\u5b83\u7684\u5904\u7406\u673a\uff0c\u5c06\u4e4b\u5206\u914d\u7ed9\u5176\u5b83\u8fdb\u7a0b\u3002\u5265\u593a\u539f\u5219\u6709\uff1a\u4f18\u5148\u6743\u539f\u5219\u3001\u77ed\u8fdb\u7a0b\u4f18\u5148\u539f\u5219 \u3001\u65f6\u95f4\u7247\u539f\u5219\u3002\u5982\u4e0a2\u30013<\/p>\n

                MEMO:\u8d85\u6307\u6570\u5206\u5e03<\/p><\/blockquote>\n

                \u8c03\u5ea6\u7a0b\u5e8f\uff1a<\/p>\n

                Dispatcher module gives control of the CPU to the process selected by the shortterm scheduler; this involves:<\/p>\n

                  \n
                • switching context<\/li>\n
                • switching to user mode<\/li>\n
                • jumping to the proper location in the user program to restart that program<\/li>\n<\/ul>\n

                  Dispatch latency\uff08\u8c03\u5ea6\u5ef6\u8fdf\uff09 \u2013 time it takes for the dispatcher to stop one process and start another running\u8c03\u5ea6\u7a0b\u5e8f\u505c\u6b62\u4e00\u4e2a\u8fdb\u7a0b\u5230\u542f\u52a8\u4e00\u4e2a\u8fdb\u7a0b\u6240\u9700\u8981\u7684\u65f6\u95f4<\/p>\n

                  Linux\u547d\u4ee4\uff1avmstat<\/p>\n

                   <\/p>\n

                  \u4e8c\u3001Scheduling Criteria \u8c03\u5ea6\u51c6\u5219<\/span><\/p>\n

                  1.\u9762\u5411\u7528\u6237(User-oriented)\u7684\u51c6\u5219\u548c\u8bc4\u4ef7<\/p>\n

                  \u5468\u8f6c\u65f6\u95f4Turnaround time<\/span><\/strong> \uff1a\u8fdb\u7a0b\u4ece\u63d0\u4ea4\u5230\u5b8c\u6210\u6240\u7ecf\u5386\u7684\u65f6\u95f4\u3002\u5305\u62ec\uff1a\u5728CPU\u4e0a\u6267\u884c\uff0c\u5c31\u7eea\u961f \u5217\u548c\u963b\u585e\u961f\u5217\u4e2d\u7b49\u5f85\u3002<\/p>\n

                    \n
                  • \u5468\u8f6c\u65f6\u95f4 T=\u5b8c\u6210\u65f6\u95f4-\u63d0\u4ea4\u65f6\u95f4<\/li>\n
                  • \u5e73\u5747\u5468\u8f6c\u65f6\u95f4=\u2211\u5468\u8f6c\u65f6\u95f4\/\u8fdb\u7a0b\u6570<\/li>\n
                  • \u5e26\u6743\u5468\u8f6c\u65f6\u95f4W= T(\u5468\u8f6c\u65f6\u95f4)\/t(CPU\u6267\u884c\u65f6\u95f4)<\/li>\n
                  • \u5e73\u5747\u5e26\u6743\u5468\u8f6c\u65f6\u95f4=\u2211W\/\u8fdb\u7a0b\u6570<\/li>\n<\/ul>\n

                    \u54cd\u5e94\u65f6\u95f4Response time<\/span><\/strong> \uff1a\u4ece\u8fdb\u7a0b\u63d0\u51fa\u8bf7\u6c42\u5230\u9996\u6b21\u88ab\u54cd\u5e94\uff08\u800c\u4e0d\u662f\u8f93\u51fa\u7ed3\u679c\uff09\u7684\u65f6\u95f4\u6bb5\uff08\u5728\u5206 \u65f6\u7cfb\u7edf\u73af\u5883\u4e0b\uff09<\/p>\n

                    \u7b49\u5f85\u65f6\u95f4Waiting time<\/span> <\/strong>\u2013 \u8fdb\u7a0b\u5728\u5c31\u7eea\u961f\u5217\u4e2d\u7b49\u5f85\u7684\u65f6\u95f4\u603b\u548c<\/p>\n

                    \u622a\u6b62\u65f6\u95f4<\/strong><\/span>\uff1a\u5f00\u59cb\u622a\u6b62\u65f6\u95f4\u548c\u5b8c\u6210\u622a\u6b62\u65f6\u95f4\uff0d\uff0d\u5b9e\u65f6\u7cfb\u7edf\uff0c\u4e0e\u5468\u8f6c\u65f6\u95f4\u6709\u4e9b\u76f8\u4f3c\u3002<\/p>\n

                    \u516c\u5e73\u6027\uff1a\u4e0d\u56e0\u4f5c\u4e1a\u6216\u8fdb\u7a0b\u672c\u8eab\u7684\u7279\u6027\u800c\u4f7f\u4e0a\u8ff0\u6307\u6807\u8fc7\u5206\u6076\u5316\u3002\u5982\u957f\u8fdb\u7a0b\u7b49\u5f85\u5f88\u957f\u65f6\u95f4\u3002<\/p>\n

                    \u4f18\u5148\u7ea7\uff1a\u53ef\u4ee5\u4f7f\u5173\u952e\u4efb\u52a1\u8fbe\u5230\u66f4\u597d\u7684\u6307\u6807<\/p>\n

                    2. \u9762\u5411\u7cfb\u7edf\u7684\u8c03\u5ea6\u6027\u80fd\u51c6\u5219<\/p>\n

                    \u541e\u5410\u91cfThroughput<\/strong><\/span> \uff1a\u5355\u4f4d\u65f6\u95f4\u5185\u6240\u5b8c\u6210\u7684\u8fdb\u7a0b\u6570\uff0c\u8ddf\u8fdb\u7a0b\u672c\u8eab\u7279\u6027\u548c\u8c03\u5ea6\u7b97\u6cd5\u90fd\u6709\u5173\u7cfb \uff0d\uff0d\u6279\u5904\u7406\u7cfb\u7edf<\/p>\n

                      \n
                    • \u5e73\u5747\u5468\u8f6c\u65f6\u95f4\u4e0d\u662f\u541e\u5410\u91cf\u7684\u5012\u6570\uff0c\u56e0\u4e3a\u5e76\u53d1\u6267\u884c\u7684\u8fdb\u7a0b\u5728\u65f6\u95f4\u4e0a\u53ef\u4ee5\u91cd\u53e0\u3002\u5982\uff1a\u57282 \u5c0f\u65f6\u5185\u5b8c\u62104\u4e2a\u8fdb\u7a0b\uff0c\u800c\u6bcf\u4e2a\u5468\u8f6c\u65f6\u95f4\u662f1\u5c0f\u65f6\uff0c\u5219\u541e\u5410\u91cf\u662f2\u4e2a\u8fdb\u7a0b\/\u5c0f\u65f6<\/li>\n<\/ul>\n

                      \u5904\u7406\u673a\u5229\u7528\u7387<\/strong><\/span>CPU utilization\uff1a\u4f7fCPU\u5c3d\u53ef\u80fd\u7684\u5fd9\u788c<\/p>\n

                      \u5404\u79cd\u8bbe\u5907\u7684\u5747\u8861\u5229\u7528<\/span><\/strong>\uff1a\u5982CPU\u7e41\u5fd9\u7684\u8fdb\u7a0b\u548cI\/O\u7e41\u5fd9\u7684\u8fdb\u7a0b\u642d\u914d\uff0d\uff0d\u5927\u4e2d\u578b\u4e3b\u673a<\/p>\n

                      3. \u8c03\u5ea6\u7b97\u6cd5\u672c\u8eab\u7684\u8c03\u5ea6\u6027\u80fd\u51c6\u5219<\/p>\n

                        \n
                      • \u6613\u4e8e\u5b9e\u73b0<\/li>\n
                      • \u6267\u884c\u5f00\u9500\u6bd4\u8f83\u5c0f<\/li>\n<\/ul>\n

                        4.\u6700\u4f18\u51c6\u5219<\/p>\n

                          \n
                        • \u6700\u5927\u7684CPU\u5229\u7528\u7387 Max CPU utilization<\/li>\n
                        • \u6700\u5927\u7684\u541e\u5410\u91cf Max throughput<\/li>\n
                        • \u6700\u77ed\u7684\u5468\u8f6c\u65f6\u95f4 Min turnaround time<\/li>\n
                        • \u6700\u77ed\u7684\u7b49\u5f85\u65f6\u95f4 Min waiting time<\/li>\n
                        • \u6700\u77ed\u7684\u54cd\u5e94\u65f6\u95f4 Min response time<\/li>\n
                        • \u516c\u5e73<\/span><\/strong><\/li>\n<\/ul>\n

                           <\/p>\n

                          \u4e09\u3001Scheduling Algorithms \u8c03\u5ea6\u7b97\u6cd5<\/span><\/p>\n

                          First-Come, First-Served (FCFS) Scheduling\u5148\u6765\u5148\u670d\u52a1\u8c03\u5ea6<\/span><\/p>\n

                          Shortest-Job-First (SJF) Scheduling \u77ed\u4f5c\u4e1a\u4f18\u5148\u8c03\u5ea6<\/span><\/p>\n

                          Priority Scheduling \u4f18\u5148\u6743\u8c03\u5ea6<\/span><\/p>\n

                          Round Robin (RR) \u65f6\u95f4\u7247\u8f6e\u8f6c\u8c03\u5ea6<\/span><\/p>\n

                          Multilevel Queue Scheduling \u591a\u7ea7\u961f\u5217\u8c03\u5ea6<\/span><\/p>\n

                          Multilevel Feedback Queue Scheduling\u591a\u7ea7\u53cd\u9988\u961f\u5217\u8c03\u5ea6<\/span><\/p>\n

                          \u9ad8\u54cd\u5e94\u6bd4\u4f18\u5148\u8c03\u5ea6\u7b97\u6cd5 Highest Response Ratio Next(HRRN)<\/span><\/strong><\/p>\n

                          \u54cd\u5e94\u6bd4R = (\u7b49\u5f85\u65f6\u95f4 + \u8981\u6c42\u6267\u884c\u65f6\u95f4) \/ \u8981\u6c42\u6267\u884c\u65f6\u95f4<\/span><\/strong>\uff08\u8003\u7814\u7528\uff09\u00a0<\/span><\/p><\/blockquote>\n

                          1.\u5148\u5230\u5148\u670d\u52a1\u8c03\u5ea6FCFS<\/p>\n

                          FCFS\u7b97\u6cd5\uff08\u975e\u62a2\u5360\uff09<\/p>\n

                            \n
                          • \u6309\u7167\u8fdb\u7a0b\u6216\u4f5c\u4e1a\u63d0\u4ea4\u987a\u5e8f\u5f62\u6210\u5c31\u7eea\u72b6\u6001\u7684\u5148\u540e\u6b21\u5e8f\uff0c\u5206\u6d3eCPU<\/span><\/strong><\/li>\n
                          • \u5f53\u524d\u8fdb\u7a0b\u6216\u4f5c\u4e1a\u5360\u7528CPU\uff0c\u76f4\u5230\u6267\u884c\u5b8c\u6216\u963b\u585e\uff0c\u624d\u51fa\u8ba9CPU\uff08\u975e\u62a2\u5360\u65b9\u5f0f \uff09<\/li>\n
                          • \u5728\u8fdb\u7a0b\u6216\u4f5c\u4e1a\u5524\u9192\u540e\uff08\u5982I\/O\u5b8c\u6210\uff09\uff0c\u5e76\u4e0d\u7acb\u5373\u6062\u590d\u6267\u884c\uff0c\u901a\u5e38\u7b49\u5230\u5f53\u524d \u4f5c\u4e1a\u6216\u8fdb\u7a0b\u51fa\u8ba9CPU<\/li>\n
                          • \u6700\u7b80\u5355\u7684\u7b97\u6cd5<\/li>\n<\/ul>\n

                            FCFS\u7684\u7279\u70b9<\/p>\n

                              \n
                            • \u6bd4\u8f83\u6709\u5229\u4e8e\u957f\u8fdb\u7a0b\uff0c\u800c\u4e0d\u5229\u4e8e\u77ed\u8fdb\u7a0b\u3002<\/li>\n
                            • \u6709\u5229\u4e8eCPU Bound\u7684\u8fdb\u7a0b\uff0c\u800c\u4e0d\u5229\u4e8eI\/O Bound\u7684\u8fdb\u7a0b\u3002<\/li>\n
                            • \u5e73\u5747\u7b49\u5f85\u65f6\u95f4\u901a\u5e38\u8f83\u957f<\/li>\n
                            • <\/li>\n<\/ul>\n

                              2.\u6700\u77ed\u4f5c\u4e1a\u4f18\u5148\u8c03\u5ea6SJF<\/p>\n

                              \u53c8\u79f0\u4e3a\u201c\u77ed\u8fdb\u7a0b\u4f18\u5148\u201dSPF(Shortest Process First)\uff1b\u8fd9\u662f\u5bf9FCFS\u7b97\u6cd5\u7684\u6539\u8fdb\uff0c\u5176\u76ee\u6807\u662f\u51cf\u5c11 \u5e73\u5747\u5468\u8f6c\u65f6\u95f4\u3002<\/p>\n

                              SJF\u7b97\u6cd5:<\/p>\n

                              \u5bf9\u9884\u8ba1\u6267\u884c\u65f6\u95f4\u77ed\u7684\u4f5c\u4e1a\uff08\u8fdb\u7a0b\uff09\u4f18\u5148\u5206\u6d3e\u5904\u7406\u673a\u3002<\/p>\n

                              Two schemes:<\/p>\n

                              nonpreemptive \u2013 once CPU given to the process it cannot be preempted until completes its CPU burst<\/p>\n

                              preemptive \u2013 if a new process arrives with CPU burst length less than remaining time of current executing process, preempt. This scheme is know as the Shortest-Remaining-Time-First (SRTF)\u5982\u679c\u65b0\u8fdb\u7a0b\u5230\u8fbe\u65f6\uff0cCPU\u8fd0\u884c\u65f6\u95f4\u5c0f\u4e8e\u5f53\u524d\u6267\u884c\u8fdb\u7a0b\u7684\u5269\u4f59\u65f6\u95f4\uff0c\u5219\u62a2\u5360\u3002<\/p>\n

                              SJF is optimal \u2013 gives minimum average waiting time for a given set of processes.\u6700\u5c0f\u5e73\u5747\u7b49\u5f85\u65f6\u95f4<\/p>\n

                              SJF\u7684\u53d8\u5f62\uff1a<\/p>\n

                              \u6700\u77ed\u5269\u4f59\u65f6\u95f4\u4f18\u5148SRT(Shortest Remaining Time)-\u57fa\u4e8e\u62a2\u5360\u7684SJF\u7b97\u6cd5<\/p>\n

                                \n
                              • \u5141\u8bb8\u6bd4\u5f53\u524d\u8fdb\u7a0b\u5269\u4f59\u65f6\u95f4\u66f4\u77ed\u7684\u8fdb\u7a0b\u6765\u62a2\u5360<\/li>\n<\/ul>\n

                                \u6700\u9ad8\u54cd\u5e94\u6bd4\u4f18\u5148HRRN(Highest Response Ratio Next)<\/p>\n

                                  \n
                                • \u54cd\u5e94\u6bd4R = (\u7b49\u5f85\u65f6\u95f4 + \u8981\u6c42\u6267\u884c\u65f6\u95f4) \/ \u8981\u6c42\u6267\u884c\u65f6\u95f4<\/li>\n
                                • \u662fFCFS\u548cSJF\u7684\u6298\u8877<\/li>\n<\/ul>\n<\/blockquote>\n","protected":false},"excerpt":{"rendered":"

                                  \u7ebf\u7a0b Threads \u4e00\u3001\u6982\u8ff0 MEMO:\u8fdb\u7a0b\u548c\u7ebf\u7a0b\u6709\u4ec0\u4e48\u533a\u522b\uff1f \u8fdb\u7a0b(Process)\u7684\u4e24\u4e2a\u7279\u6027\uff1a […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[16,20],"tags":[],"_links":{"self":[{"href":"http:\/\/www.magicmipamipa.com\/index.php?rest_route=\/wp\/v2\/posts\/806"}],"collection":[{"href":"http:\/\/www.magicmipamipa.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.magicmipamipa.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.magicmipamipa.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.magicmipamipa.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=806"}],"version-history":[{"count":3,"href":"http:\/\/www.magicmipamipa.com\/index.php?rest_route=\/wp\/v2\/posts\/806\/revisions"}],"predecessor-version":[{"id":810,"href":"http:\/\/www.magicmipamipa.com\/index.php?rest_route=\/wp\/v2\/posts\/806\/revisions\/810"}],"wp:attachment":[{"href":"http:\/\/www.magicmipamipa.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=806"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.magicmipamipa.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=806"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.magicmipamipa.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=806"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}