技术研究论文集--共享内存

综合结算产品部技术专题研究功能规格说明书共享内存分册A1A0A2A3ZHJS_BASELIB_V10A4A5A6A7A8A9A10A11A8A9A12A13A14A15A16A1710A18A19A20A21A22A23A24A25A26A27A28A29A30A31A32A28A29A30A31A32A33A14A15A34A35A36A34A35A37A382010513A14A15A20A21A36A20A21A37A38A39A40FROMDATEPHONE/FAXTOACTIONDUEDATEPHONE/FAXACTIONTYPESAPPROVE,REVIEW,INFORM,FILE,ACTIONREQUIRED,ATTENDMEETING,OTHERPLEASESPECIFYA41A42A43A44A45A46A47A48A49A47A48A50A51A52A53A54A55A56A57A58012010513A59A60A61A62A63A61A62A64A65A66A67A68A69A70A71A72A63A47A73A74A75ALLRIGHTSRESERVEDNEITHERTHEWHOLENORANYPARTSOFTHISDOCUMENTMAYBEREPRODUCED,STOREDINANYRETRIEVALSYSTEMORTRANSMITTED,INANYFORMORBYANYMEANS,WITHOUTTHEPRIORWRITTENCONSENTOFTHECOPYRIGHTOWNERCOPYRIGHT2007BYA76A61A77A78A79A80A81A82A83A84A85ALLRIGHTSRESERVEDA86A87A88COPYRIGHT2007BYA76A61A77A78A79A80A81A82A83A84A8531A89A90A91A92511A89A90A93A94A95A96512A89A90A97A98A99A100513A101A102A103A104514A105A106A107A108A109515A110A111A89A90516A89A90A112A11352A114A115A116A117521A112A118522A119A120623A121A122A123A124A125724A126A127A128A129A130A1318241A132A133A134A135A136A128A129A130A13182411A137A138A139A140A141A142A143A114A115A116A117A12482412A144A145A142A143A114A115A116A117A12492413A146A14792414A148A145A146A147102414A149A150112415A146A147A124A151A152112416A153A154A114A115A116A117122417A155A156A114A115A116A117A157A158122418A159A127A160A16112242A134A162A134A163A164A165A166A119A12014243A134A162A134A163A164A165A166A128A129A130A131152431A167A140A141A139A137A138A142A168A114A115A116A117A124152432A114A115A116A117A169A170A171A172172433A114A115A116A117A173A174A171A172182434A144A145A114A115A116A117182435A159A127A160A1611925A126A175A176A17721251A178A135A136A179A180A181A182A183A184A96A176A17721252A185A132A186A187A136A188A189A190A191A192A193A190A96A194A19524253A99A149A142A114A115A116A117A96A196A170A129A197A15224254A134A198A199A183A200A201A180A202A203A179A96A180A181A182A204A184A205A12727255A180A181A182A206A184A199A128A129A96A207A208281文档介绍11文档编写目的随着结算系统和IDEP系统的发展，进程间通信越频繁，本文介绍了UNIX系统提供的进程间最快的通信方式共享内存的基本函数和原理。12文档阅读对象1UNIX学习者2系统维护人员3系统开发人员13涵盖范围14缩略语定义15参考文档1UNIX环境高级编程2LINUX常用C函数（中文版）16文档概要2共享内存21概念所谓共享内存就是多个进程间共同使用同一段物理内存空间,它是通过将同一段物理内存映射到不同进程的虚空间中来实现的。由于映射到不同进程的虚空间中,不同进程可以直接使用,不需要进行内存的复制,所以共享内存的效率很高。22原理在系统内核为一个进程分配内存地址时，通过分页机制可以让一个进程的物理地址不G17842G13505，同时G1075可以让一段内存同时分配G13485不同的进程。G3926G991G32822G161所G12046G726G3282G7262G161G17837G3371共享虚G6323内存的页G19766，G1998现在G8611一个共享G16825页G19766的进程的页G15932中。G1306是它不需要在所G7389进程的虚G6323内存中G18129G7389G11468同的虚G6323地址。G3926G991G32822G162所G12046G29G3282G7262G16223类型与区别共享内存分为G1016G12193G726PG50G54IX的共享内存和G86G92G86G87G72G80G57的共享内存。G1120者是用同一G12193机制G4448G6116的，G1306是存在着一G4462的G2318G2047。1G17不同的是用G6155接G2487G726PG50G54IX的共享内存，通过用G6155空间G6358G17745的G87G80G83G73G86文G1226系统实现的。G54G60G54G55EG48G57的共享内存，是由内核本G17535的G87G80G83G73G86实现的。2G17不同的G16855用接G2487G726PG50G54IX的共享内存机制实G19481G990在G5223过程中以G2462用G6155空间的G1866G1194G18108分G15999展G12046为G4448G1852的文G1226系统的G16855用过程，在G16855用G4448G86G75G80G66G82G83G72NG1055G2530，需要G16855用G80G80G68G83来将G87G80G83G73G86的文G1226映射到地址空间，接着就可以G6817G1328G17837个文G1226了，需要G8892G5859的是，G2047的进程G1075可以G6817G1328G17837个文G1226，G3252G8504G17837个文G1226G1866实就是共享内存。G54G60G54G55EG48G57的共享内存，内核直接实现了G86G75G80G74G72G87G18G68G87系统G16855用，G15441G9994最G13468G1075是G19764G87G80G83G73G86来实现的，G1306是接G2487G16786G16757G990和G83G82G86IXG4448G1852不同。PG50G54IXG7100在提供所G7389系统G18129一G14280的接G2487。G54G60G54G55EG48G57G2494在于实现G14270G5061的G17935G17765，共享内存G1866实G2494是G86G92G86G89中IG83G70的一G18108分，最G13468的G12661理数G6466结G7512G1075是IG83G70的G13792不是共享内存的3G17不同的G9052G17876方式G726不G12661是G54G60G54G55EG48G57的G17836是PG50G54IX的共享内存，在G1039机G18337G2563G1055G2530G18129不复存在，G3252为数G6466是G18129G1457存在物理存G1660G3132G990G6122G1144G6454分G2318中。G1194G1216不同的是G726PG50G54IX是以用G6155空间文G1226实现的，G5194G1000用G6155空间G6817G1328的是文G1226G6563G17860G12538，文G1226G6563G17860G12538是G4658于G87G68G86G78G66G86G87G85UG70G87的，G3252G8504进程G17876G1998G1055G2530共享内存将G17894G1955共享G16757数，G3926G7536为G19的时G1517G2029G19156G8597。G3252G8504PG50G54IX的共享内存G15441G9994使用G50PEN来G2031G5326G6122G6183开共享内存G5194G8821G7389用G70LG82G86G72G13792是用UNLING78来关闭的，G1328用就是在G16757数为G19的时G1517G19156G8597它。G54G60G54G55EG48G57的共享内存，G15441G9994G1075是由文G1226实现的，G1306是文G1226G5194G8821G7389加到进程的G6183开文G1226G15932，G13792是G1328为进程的一G12193内在G4658性G15999使用的，G3252G8504在进程G17876G1998时G5194不关闭文G1226，G2494要机G3132不G18337G2563G6122不显式G19156G8597，那么共享内存将一直存在，进程和文G1226G1866实是互不G11468关的G1016个概念，G2494是进程G6183开的文G1226才和进程G11468关，在进程结束的时G1517G2494是能G1457证与G1055G11468关的文G1226G15999关闭，G13792G2047的文G1226比G3926G54G60G54G55EG48G57的共享内存使用的文G1226结G7512G8821G7389和进程关联，G3252G8504不会G15999关闭。G1866实G70LG82G86G72G5194不G6817G1328什么，G13792是仅仅刷新缓冲G2318，G9994G2530G17894G1955文G1226的使用者G16757数。4不同的通用性G726G54G60G54G55EG48G57共享内存存在时间比较老，许多系统G18129支持，G1306是接G2487复杂G5194G1000可能各平台G990实现略G7389G2318G2047。PG50G54IX共享内存是新标准，现在多数UNIX已实现，语法简单，G5194G1000各平台G990实现G18129一样。5不同的大小限制G726PG50G54IX的大小可以在任何时刻通过G16855用G73G87G85UNG70G68G87G72修改，G13792G54G60G54G55EG48G57共享内存对象的大小是在G16855用G86G75G80G74G72G87G2031G5326时已经固G4462G991来的。PG50G54IX共享内存的大小、数量G2494受系统文G1226限制，G13792G54G60G54G55EG48G57共享内存对象的大小、数量受内核参数限制。24常用函数说明241POSIX函数说明PG50G54IX共享内存G2318涉G2462G1016个步骤G7261、指G4462一个名字参数G16855用G86G75G80G66G82G83G72N,以G2031G5326一个新的共享内存G2318对象G6122G6183开一个以存在的共享内存G2318对象。2、G16855用G80G80G68G83把G17837个共享内存G2318映射到G16855用进程的地址空间。传G17894G13485G86G75G80G66G82G83G72N的名字参数随G2530由希望共享G16825内存G2318的任何G1866G1194进程使用。2411打开或创建一个共享内存区函数介绍G726A209A210SHM_OPENA211A212G6183开G6122G2031G5326一个共享内存G2318A213A214A215INCLUDEA214A215A216A217INTSHM_OPENCONSTCHARNAME,INTOFLAG,MODE_TMODEA218A215NAME共享内存G2318的名字CFLAG标志位MODE权限位A219A220A221G6116功返回0，G1998错返回1参数详解G726G70G73LG68G74G726必须含G7389G50G66RDG50NLG60和G50G66RDWR标志，G17836可以指G4462G3926G991标志G726G50G66CREAG55,G50G66EXCLG6122G50G66G55RUNC。G80G82DG72G29指G4462权限位，它指G4462G50G66CREAG55标志的前提G991使用。返回值G726G86G75G80G66G82G83G72N的返回值是一个整数G6563G17860字，它随G2530用G1328G80G80G68G83的第五个参数。2412删除一个共享内存区函数介绍G726A222A223SHM_UNLINKA224A225删除一个共享内存G2318A226A227A228INCLUDEA227A228A229A230INTSHM_UNLINKCONSTCHARNAMEA231A228NAME共享内存G2318的名字A232A233A234G6116功返回0，G1998错返回1G8892G5859点G726G86G75G80G66UNLING78函数删除一个共享内存G2318对象的名字，删除一个名字仅仅防止G2530G13505的G82G83G72N,G80QG66G82G83G72NG6122G86G72G80G66G82G83G72NG16855用取得G6116功。2413映射函数介绍G726A235A236MMAPA237A238把I/O文G1226映射到一个存G1660G2318域中A239A240A241INCLUDEA240A241A242A243VOIDMMAPVOIDADDR,SIZE_TLEN,INTPROT,INTFLAG,INTFILEDES,OFF_TOFFA244A241ADDR指向映射存G1660G2318的起始地址LEN映射的字节PROT对映射存G1660G2318的G1457护要求FLAGFLAG标志位FILEDES要G15999映射文G1226的G6563G17860G12538OFF要映射字节在文G1226中的起始偏移量A245A246A247若G6116功G2029返回映射G2318的起始地址，若G1998错G2029返回MAP_FAILED参数详解G726G68DDG85G726用于指G4462映射存G1660G2318的起始地址。通常将G1866G16786置为NULL，G17837G15932G12046由系统选择G16825映射G2318的起始地址。G73ILG72DG72G86G726指要G15999映射文G1226的G6563G17860G12538。在映射G16825文G1226到一个地址空间G1055前，先要G6183开G16825文G1226。LG72N是映射的字节数。G82G73G73G29是要映射字节在文G1226中的起始偏移量。通常将G1866G16786置为G19。G83G85G82G87G29说明对映射存G1660G2318的G1457护要求。可将G83G85G82G87参数指G4462为PRG50G55G66NG50NE,G6122者是PRG50G55G66READ映射G2318可读,PRG50G55G66WRIG55E（映射G2318可写）,PRG50G55G66EXEC（映射G2318可执行）任G5859组合的按位G6122，G1075可以是PRG50G55G66NG50NE映射G2318不可访问。对指G4462映射存G1660G2318的G1457护要求不能超过文G1226G82G83G72N模式访问权限。G73LG68G74G29影响映射G2318的多G12193G4658性G726G48APG66FIXED返回值必须G12573于G68DDG85G17G3252为G17837不G2045于可移G7905性，所以不G21735G2181使用G8504标志。G48APG66G54G43AREDG17837一标志说明了本进程对映射G2318所进行的存G1660G6817G1328的配置。G8504标志指G4462存G1660G6817G1328修改映射文G1226。G48APG66PRIG57AG55E本标志G4560G14280对映射G2318G5326G12447一个G16825映射文G1226的一个G12181G7389G2115本。所G7389G2530来对G16825映射G2318的G5353用G18129是G5353用G16825G2115本，G13792不是原始文G1226。G8892G5859点G726必须指G4462G48APG66FIXEDG6122G48APG66PRIG57AG55E标志G1866中的一个，指G4462前者是对存G1660映射文G1226本G17535的一个G6817G1328，G13792G2530者是对G1866G2115本进行G6817G1328。G80G80G68G83G6116功返回G2530，G73D参数可以关闭。G16825G6817G1328对于由G80G80G68G83G5326G12447的映射关系G8821G7389影响。2414解除映射函数介绍G726A248A249MUNMAPA250A251解除存G1660映射A252A253A254INCLUDEA253A254A255A88INTMUNMAPCADDR_TADDR,SIZE_TLENA72A254ADDR指向映射存G1660G2318的起始地址LEN映射的字节A164A0A1若G6116功G2029返回0，若G1998错G2029返回1参数详解G726G68DDG85参数是由G80G80G68G83返回的地址，LG72N是映射G2318的大小。G8892G5859点G726解除映射G2530，G1889G8437访问G17837G1135地址G4560G14280向G16855用进程G1147G10995一个G54IG42G54EG42G57信G2507。2414同步函数介绍G726A3A2MSYNCA32A4同步文G1226到存G1660G3132A163A5A6INCLUDEA5A6A7A8INTMSYNCVOIDADDR,SIZE_TLEN,INTFLAGSA9A6ADDR指向映射存G1660G2318的起始地址LEN映射的字节PROTFLAGSA10A11A12若G6116功G2029返回0，若G1998错G2029返回1参数详解G726G68DDG85和LG72NG726通常指G1207内存中的整个内存映射G2318，不过G1075可以指G4462G16825内存G2318的一个G4388G19610。G73LG68G74G86G726为G48G54G66AG54G60NC执行G5334步写，G48G54G66G54G60NC（执行同步写），G48G54G66ING57ALIDAG55E（使高G17907缓存的数G6466实效）。G1866中G48G54G66AG54G60NC和G48G54G66G54G60NCG17837G1016个常值中必须指G4462一个，G1306不能G18129指G4462。它G1216的G5058G2047是G726一G7098写G6817G1328已由内核G6502G1849G19443G2027，G48G54G66AG54G60NCG2375返回，G13792G48G54G66G54G60NCG2029要G12573到写G6817G1328G4448G6116G2530才返回。G3926G7536G17836指G4462了G48G54G66ING57ALIDAG55E，那么与G1866最G13468G6347G17137不一G14280的文G1226数G6466的所G7389内存中G6347G17137G18129G3845效，G2530G13505的G5353用将G1186文G1226取得数G64662415映射区复制函数介绍G726A13A14MEMCPYA15A16复制映射存G1660G2318A17A18A19INCLUDEA18A19A20A21VOIDMEMCPYVOIDDEST,CONSTVOIDSRC,SIZE_TNA22A19DEST复制G2530的映射存G1660G2318SRCG5465复制的映射存G1660G2318NG5465复制的映射存G1660G2318的大小A23A24A25返回DEST的G20330地址2416改变共享内存函数介绍G726A26A27FTRUNCATEA28A29G16855整文G1226G6122共享内存G2318大小A30A31A33INCLUDEA31A33A34A35INTFTRUNCATEINTFD,OFF_TLENGTHA36A33FDG6563G17860G12538LENGTH大小A37A38A39G6116功返回0，G1998错返回12417获得共享内存信息函数介绍G726A40A41FSTATA42A43G14731得文G1226G6122共享内存G2318的信G5699A44A45A46INCLUDEINCLUDEINCLUDEA45A46A47A48INTSTATCONSTCHARFILE_NAME,STRUCTSTATBUFA49A46FILE_NAME文G1226名BUFSTAT结G7512A50A51A52G6116功返回0，G1998错返回1G8892G5859点G726对于G7234通文G1226G86G87G68G87结G7512可以G14731得12个以G990的G6116员信G5699，G9994G13792G5415G73D指G1207一个共享内存G2318对象时，G2494G7389G3247个G6116员含G7389信G5699。G86G87G85UG70G87G86G87G68G87G94G80G82DG72G66G87G86G87G66G80G82DG72G30UIDG66G87G86G87G66UIDG30G74IDG66G87G86G87G66G74IDG30G82G73G73G66G87G86G87G66G86IG93G72G30G96G302418应用举例G6117G1216系统的G1375G4388G16G16G16G16G8981程G16855G5242A53A54A55A56A57A58A54A53A59A60A61A62A63A63A64A65A65A66A67A67A61A68A69A70A71A73A73A74A75A76A77A78A79A73A80A81A75A82A80A83A78A84A85A86A87A87A89A90A91A92A93A94A95A91A90A79A70A96A96A82A84A70A79A73A80A97A98A99A80A100A96A76A84A70A71A73A73A74A75A76A77A78A79A73A80A81A75A82A80A83A85A84A101A102A103A101A87A87A104A105A87A89A80A106A79A76A96A107A108A87A109A110A90A91A111A112A94A95A113A114A115A91A90A116A79A70A117A80A70A84A118A74A84A82A84A99A119A75A76A120A77A78A79A73A80A97A96A121A84A119A75A76A120A77A122A100A70A98A91A87A82A82A75A99A96A105A83A96A123A79A124A80A84A76A87A82A84A70A79A73A80A121A79A124A80A91A123A79A124A80A98A70A96A121A84A119A75A76A120A77A122A100A70A98A87A83A74A101A85A125A84A103A101A122A125A126A127A74A101A85A125A84A101A126A128A102A83A129A128A74A84A121A118A128A101A126A102A127A129A128A74A84A128A102A102A101A130A131A83A82A84A70A79A73A80A83A105A87A109A116A80A73A123A80A82A84A99A119A75A76A120A77A78A79A73A80A97A96A121A84A119A75A76A120A77A122A100A70A98A91A87A82A82A75A99A96A105A83A96A123A79A124A80A84A76A87A82A84A70A79A73A80A121A79A124A80A91A123A79A124A80A98A70A96A121A84A119A75A76A120A77A122A100A70A98A87A83A74A101A85A125A84A103A101A122A125A126A127A74A101A85A125A84A101A126A128A102A83A129A128A74A84A121A118A128A101A126A102A83A82A84A70A79A73A80A83A105A87A109A116A80A100A117A79A70A79A70A96A129A128A74A84A78A128A122A132A126A102A97A97A82A84A99A119A75A76A120A77A78A79A73A80A87A89A80A106A79A76A96A107A108A87A109A110A110A80A73A123A80A89A90A91A108A133A134A135A136A92A93A94A95A91A90A79A70A96A96A82A84A70A79A73A80A97A98A99A80A100A96A76A84A70A71A73A73A74A75A76A77A78A79A73A80A81A75A82A80A83A85A84A101A102A103A101A127A85A84A137A101A126A128A125A127A85A84A125A101A138A81A137A83A74A126A101A129A121A87A87A104A105A87A89A80A106A79A76A96A107A108A87A109A110A90A91A131A133A139A140A91A90A79A70A96A73A123A80A80A141A96A82A84A70A79A73A80A83A123A79A124A80A98A70A96A121A84A119A75A76A120A77A122A100A70A98A87A91A82A84A70A79A73A80A121A79A124A80A107A108A83A121A126A126A86A84A121A126A125A87A104A105A87A89A80A106A79A76A96A107A108A87A109A110A79A70A96A142A143A79A76A80A96A82A84A70A79A73A80A83A144A144A83A108A87A145A97A108A87A89A80A106A79A76A96A107A108A87A109A110A90A91A111A112A94A95A113A114A115A91A90A116A79A70A117A80A70A84A118A74A84A82A84A99A119A75A76A120A77A78A79A73A80A97A96A121A84A119A75A76A120A77A122A100A70A98A91A87A82A82A75A99A96A105A83A96A123A79A124A80A84A76A87A82A84A70A79A73A80A121A79A124A80A91A123A79A124A80A98A70A96A121A84A119A75A76A120A77A122A100A70A98A87A83A74A101A85A125A84A103A101A122A125A126A127A74A101A85A125A84A101A126A128A102A83A129A128A74A84A121A118A128A101A126A102A127A129A128A74A84A128A102A102A101A130A131A83A82A84A70A79A73A80A83A105A87A109A116A80A73A123A80A82A84A99A119A75A76A120A77A78A79A73A80A97A96A121A84A119A75A76A120A77A122A100A70A98A91A87A82A82A75A99A96A105A83A96A123A79A124A80A84A76A87A82A84A70A79A73A80A121A79A124A80A91A123A79A124A80A98A70A96A121A84A119A75A76A120A77A122A100A70A98A87A83A74A101A85A125A84A103A101A122A125A126A127A74A101A85A125A84A101A126A128A102A83A129A128A74A84A121A118A128A101A126A102A83A82A84A70A79A73A80A83A105A87A109A116A80A100A117A79A70A79A70A96A129A128A74A84A78A128A122A132A126A102A97A97A82A84A99A119A75A76A120A77A78A79A73A80A87A89A80A106A79A76A96A107A108A87A109A110A90A91A146A147A148A114A115A91A90A82A80A82A123A80A76A96A82A84A99A119A75A76A120A77A78A79A73A80A83A105A83A82A84A70A79A73A80A121A79A124A80A91A123A79A124A80A98A70A96A121A84A119A75A76A120A77A122A100A70A98A87A87A109A90A91A146A147A148A94A95A91A90A82A123A149A100A120A96A96A120A77A75A143A91A87A82A84A99A119A75A76A120A77A78A79A73A80A83A82A84A70A79A73A80A121A79A124A80A91A123A79A124A80A98A70A96A121A84A119A75A76A120A77A122A100A70A98A87A83A129A121A84A121A150A81A137A127A129A121A84A122A81A151A128A132A122A102A128A125A126A87A109A110在G8981程G16855G5242G18336G19766，G17837一G18108分G1039要用于共享内存中G6221G8437G19154G15932中的G6221G8437信G5699实时G14865地用的。242SYSTEMV原理系统G57共享内存通过G86G75G80G74G72G87G14731得G6122G2031G5326一个IPC共享内存G2318域，G5194返回G11468G5224的标G16794G12538。内核在G1457证G86G75G80G74G72G87G14731得G6122G2031G5326一个共享内存G2318，G2033始G2282G16825共享内存G2318G11468G5224的G86G75G80IDG66G78G72G85NG72L结G7512G8892同时，G17836将在G10317G8542文G1226系统G86G75G80中，G2031G5326G5194G6183开一个同名文G1226，G5194在内存中G5326G12447起G16825文G1226的G11468G5224DG72NG87G85G92G2462ING82DG72结G7512，新G6183开的文G1226不G4658于任何一个进程（任何进程G18129可以访问G16825共享内存G2318）。所G7389G17837一G2011G18129是系统G16855用G86G75G80G74G72G87G4448G6116的。G8611一个共享内存G2318G18129G7389一个G6523制结G7512G86G87G85UG70G87G86G75G80IDG66G78G72G85NG72L，G86G75G80IDG66G78G72G85NG72L是共享内存G2318域中G19762常G18337要的一个数G6466结G7512，它是存G1660G12661理和文G1226系统结合起来的G7737G7765，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员G1660存了共享内存对象的存取权限G2462G1866它一G1135信G5699。G86G75G80G66G86G72G74G86G93G6116员G4462G1053了共享的内存大小（以字节为单位）。G86G75G80G66G68G87IG80G72G6116员G1457存了最G17829一G8437进程G17842接共享内存的时间。G86G75G80G66DG87IG80G72G6116员G1457存了最G17829一G8437进程G7041开与共享内存的G17842接的时间。G86G75G80G66G70G87IG80G72G6116员G1457存了最G17829一G8437G86G75G80IDG66DG86结G7512内G4493改G2476的时G86G75G80G66G70G83IDG6116员G1457存了G2031G5326共享内存的进程的G83ID。G86G75G80G66LG83IDG6116员G1457存了最G17829一G8437G17842接共享内存的进程的G83ID。G86G75G80G66NG68G87G87G70G75G6116员G1457存了与共享内存G17842接的进程数G11458。G16825结G7512中最G18337要的一个域G5224G16825是G86G75G80G66G73ILG72，它存G1660了将G15999映射文G1226的地址。G8611个共享内存G2318对象G18129对G5224G10317G8542文G1226系统G86G75G80中的一个文G1226，一G14336G5785G1929G991，G10317G8542文G1226系统G86G75G80中的文G1226是不能用G85G72G68D、G90G85IG87G72G12573方法访问的，G5415G18331取共享内存的方式把G1866中的文G1226映射到进程地址空间G2530，可直接G18331用访问内存的方式对G1866访问。G17837G18336G6117G1216G18331用G621G64中的G3282G15932G13485G1998与系统G57共享内存G11468关数G6466结G7512G726内核通过数G6466结G7512G86G87G85UG70G87IG83G70G66IDG86G86G75G80G66IDG86维护系统中的所G7389共享内存G2318域。G990G3282中的G86G75G80G66IDG86G17G72NG87G85IG72G86G2476量指向一个IG83G70G66ID结G7512数组，G13792G8611个IG83G70G66ID结G7512数组中G7389个指向G78G72G85NG66IG83G70G66G83G72G85G80结G7512的指G19036。对于系统G57共享内存G2318来说，G78G72G85NG66IG83G70G66G83G72G85G80的G4499G1039是G86G75G80IDG66G78G72G85NG72L结G7512，G86G75G80IDG66G78G72G85NG72L是用来G6563G17860一个共享内存G2318域的，G17837样内核就能G3827G6523制系统中所G7389的共享G2318域。同时，在G86G75G80IDG66G78G72G85NG72L结G7512的G73ILG72G12879G3423指G19036G86G75G80G66G73ILG72指向文G1226系统G86G75G80中G11468G5224的文G1226，G17837样，共享内存G2318域就与G86G75G80文G1226系统中的文G1226对G5224起来。243SYSTEMV函数说明G54G60G54G55EG48G57共享内存G2318涉G2462以G991步骤G7261G17开G17779一G3371共享内存G86G75G80G74G72G872G17G1813许本进程使用共G7588G3371共享内存G86G75G80G68G873G17写G1849G18读G1998G23G17G12117止本进程使用G17837G3371共享内存G86G75G80DG87G24G17删除G17837G3371共享内存G86G75G80G70G87LG6122者G2641G1208行G991IG83G70G85G802431以创建或打开一块共享内存区函数介绍G726A152A153SHMGETA154A155G14731得文G1226G6122共享内存G2318的信G5699A156A157A158INCLUDEA157A158A159A160INTSHMGETKEY_TKEY,INTSIZE,INTSHMFLAGA161A162KEY共享内存的标G16794G12538SIZE大小SHMFLAG内存的模式MODE以G2462权限标G16794A165A166A167G6116功返回标G16794，G1998错返回1参数详解G726KEY在IPC的通信模式G991，不G12661是使用G9052G5699G19443G2027G17836是共享内存，G10990G14279是信G2507量，G8611个IPC的对象G82G69G77G72G70G87G18129G7389G2819一的名字，G12228为G256G19202G257G78G72G92。通过G256G19202G257，进程能G3827G16794G2047所用的对象。G256G19202G257与IPC对象的关系就G3926同文G1226名G12228G1055于文G1226，通过文G1226名，进程能G3827读写文G1226内的数G6466，G10990G14279多个进程能G3827共用一个文G1226。G13792在IPC的通G16771模式G991，通过G256G19202G257的使用G1075使得一个IPC对象能为多个进程所共用。LINUX系统中的所G7389G15932G12046G54G92G86G87G72G80G57中IPC对象的数G6466结G7512G18129G2265G6336一个IG83G70G66G83G72G85G80结G7512，G1866中G2265含G7389IPC对象的G19202值，G16825G19202用于G7609G6226G54G92G86G87G72G80G57中IPC对象的G5353用标G16794G12538。G3926G7536不使用G256G19202G257，进程将G7092法存取IPC对象，G3252为IPC对象G5194不存在于进程本G17535使用的内存中。G46G72G92使用者要显G12046G4462G1053。SIZEG86IG93G72是要G5326G12447共享内存的G19283G5242。所G7389的内存分配G6817G1328G18129是以页为单位的。所以G3926G7536一段进程G2494G11015G16843一G3371G2494G7389一个字节的内存，内存G1075会分配整整一页在I3G27G25机G3132中一页的G