内存受限系统

《内存受限系统》由会员上传分享，免费在线阅读，更多相关内容在行业资料-天天文库。

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