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1、ThinkingSmallTheProcessesforCreatingSmallMemorySoftware?2004CharlesWeir,JamesNoble.Abstract:Thispaperdescribessomeprocesspatternsforteamstofollowwhencreatingsoftwaretoruninlimitedmemory.Itisadraftversionofachaptertoaddtotheauthors’bookSmallMemorySoftware,andfollowsthestructureofotherchapters
2、inthatbook.MajorTechnique:ThinkingSmallA.k.aSmallmethodology,‘Real’programming.Howshouldyouapproachasmallsystem?·You’redevelopingasystemthatwillbememory-constrained.·Therearemanycompetingconstraintstosatisfy·Ifdifferentdeveloperstakedifferentviewsonwhichthingstooptimise,theywillproduceaninco
3、nsistentsystemthatsatisfiesnoneoftheconstraints.You'reworkingonaprojectandyoususpecttherewillberesourcelimitationsinthetargetsystem.Forexample,thedevelopersofthe‘Super-spy007’versionfortheStrap-it-Onwrist-mountedcomputerfaceasystemwithonly200KbofRAMand2MbROM.Howaretheytoadjudicatethedemandso
4、fthevoicerecognitionsoftware,thevocabulariesandthesoftware-basedradio,tomakeitasecretagent'sdreamtoy?ShouldtheystorethevocabulariesinROMtosaveRAMspace,orkeeptheminRAMtoallowthemtochangefromRussiantoArabiconthefly?What,inshort,isimportantintheirsystem,andwhatislessso?Inmanyprojectsit’sclearfr
5、omtheoutsetthatthedevelopmentteamwillhavetospendatleastsometimeandeffortsatisfyingthesystem’smemorylimitations.Youhavetocutyourcoattofityourcloth.Yetiftheteamjustspendslotsofeffortoptimisingeverythingtoworkinverylimitedmemory,they'llwastealotoftimeormaybeproduceaproductthatcouldhavebeenmuchb
6、etter.Worsestilltheproductmayfailtoworkatallbecausetheyhavebeenoptimisingthewrongthing.Forexample,anyofthefollowingfacilitiesmaybelimited:·Heap(RAM)spaceforthewholesystem·Heapspaceforindividualprocesses(ifthemaximumheapsizeofaprocessisfixed)·Processstacksize·Secondarystorageuse·ROMspace(forp
7、rogramsthatexecutefromROM)Optimisingoneofthesewilloftenbeatacostfromoneoftheothers.Inadditiontechniquesthatoptimisememoryusewilltendtocompromisetime-performance,usabilityorboth.Inanysystemthearchitectswillhavetomoderatethedemandsofdifferentcomponen
