欢迎来到人人文库网! | 帮助中心 人人文库renrendoc.com美如初恋!
人人文库网
首页 人人文库网 > 资源分类 > PDF文档下载

31-Lockup-Free Instruction FetchPrefetch Cache Organization.pdf

  • 资源大小:420.46KB        全文页数:7页
  • 资源格式: PDF        下载权限:游客/注册会员/VIP会员    下载费用:5
游客快捷下载 游客一键下载
会员登录下载
下载资源需要5

邮箱/手机号:
您支付成功后,系统会自动为您创建此邮箱/手机号的账号,密码跟您输入的邮箱/手机号一致,以方便您下次登录下载和查看订单。注:支付完成后需要自己下载文件,并不会自动发送文件哦!

支付方式: 微信支付    支付宝   
验证码:   换一换

友情提示
2、本站资源不支持迅雷下载,请使用浏览器直接下载(不支持QQ浏览器)
3、本站资源下载后的文档和图纸-无水印,预览文档经过压缩,下载后原文更清晰   

31-Lockup-Free Instruction FetchPrefetch Cache Organization.pdf

LOCKUPFREEINSTRUCTIONFETCH/PREFETCHCACHEORGANIZATIONDAVIDKROFTCONTROLDATACANADA,LTDCANADIANDEVELOPMENTDIVISIONMISSISSAUGA,ONTARIO,CANADAABSTRACTINTHEPASTDECADE,THEREHASBEENMUCHLITERATUREDESCRIBINGVARIOUSCACHEORGANIZATIONSTHATEXPLOITGENERALPROGRAMMINGIDIOSYNCRASIESTOOBTAINMAXIMUMHITRATETHEPROBABILITYTHATAREQUESTEDDATUMISNOWRESIDENTINTHECACHELITTLE,IFANY,HASBEENPRESENTEDTOEXPLOIT1THEINHERENTDUALINPUTNATUREOFTHECACHEAND2THEMANYDATUMREFERENCETYPECENTRALPROCESSORINSTRUCTIONSNOMATTERHOWHIGHTHECACHEHITRATEIS,ACACHEMISSMAYIMPOSEAPENALTYONSUBSEQUENTCACHEREFERENCESTHISPENALTYISTHENECESSITYOFWAITINGUNTILTHEMISSEDREQUESTEDDATUMISRECEIVEDFROMCENTRALMEMORYAND,POSSIBLY,FORCACHEUPDATEFORTHETWOCASESABOVE,THECACHEREFERENCESFOLLOWINGAMISSDONOTREQUIRETHEINFORMATIONOFTHEDATUMNOTRESIDENTINTHECACHE,ANDARETHEREFOREPENALIZEDINTHISFASHIONINTHISPAPER,ACACHEORGANIZATIONISPRESENTEDTHATESSENTIALLYELIMINATESTHISPENALTYTHISCACHEORGANIZATIONALFEATUREHASBEENINCORPORATEDINACACHE/MEMORYINTERFACESUBSYSTEMDESIGN,ANDTHEDESIGNHASBEENIMPLEMENTEDANDPROTOTYPEDANEXISTINGSIMPLEINSTRUCTIONSETMACHINEHASVERIFIEDTHEADVANTAGEOFTHISFEATURE;FUTURE,MOREEXTENSIVEANDSOPHISTICATEDINSTRUCTIONSETMACHINESMAYOBVIOUSLYTAKEMOREADVANTAGEPRIORTOPROTOTYPING,SIMULATIONSVERIFIEDTHEADVANTAGEINTRODUCTIONACACHEBUFFERT,2ISASMALL,FASTMEMORYHOLDINGMOSTRECENTLYACCESSEDDATAANDITSSURROUNDINGNEIGHBORS,BECAUSETHEACCESSTIMEOFTHISBUFFERISUSUALLYANORDEROFMAGNITUDEGREATERTHANMAINORCENTRALMEMORY,ANDTHESTANDARDSOFTWAREPRACTICEISTOLOCALIZEDATA,THEEFFECTIVEMEMORYACCESSTIMEISCONSIDERABLYREDUCEDWHENACACHEBUFFERISINCLUDEDTHECOSTINCREMENTFORTHISWHENCOMPAREDWITHTHECOSTOFCENTRALMEMORYALONGWITHTHEABOVEACCESSTIMEADVANTAGEINFERSCOSTEFFECTIVENESSACACHEMISS,SPACEALLOCATION,ANDREPLACEMENTALGORITHMSTOMAXIMIZEHITRATEANOTHERMETHODPRESENTEDTOINCREASETHEHITRATEWASSELECTIVEPREFETCHINQALLTHESEMETHODSASSUMETHECACHECANHANDLEONLYONEREQUESTATATIME;ONAMISS,THECACHESTAYSBUSYSERVICINGTHEREQUESTUNTILTHEDATAISRECEIVEDFROMMEMORYAND,POSSIBLY,FORCACHEBUFFERUPDATEINTHISPAPER,ACACHEORGANIZATIONISPRESENTEDTHATINCREASESTHEEFFECTIVENESSOFANORMALCACHEINCLUSIONBYUSINGTHEINHERENTDUALINPUTNATUREOFANOVERALLCACHEANDTHEMANYDATAREFERENCEINSTRUCTIONSINOTHERWORDS,ITWOULDBEEXTREMELYUSEFULTOPIPELINETHEREQUESTSINTOTHECACHEATTHECACHEHITTHROUGHPUTRATEREGARDLESSOFANYMISSESIFTHISCOULDBEACCORNPLISHEDTHENALLFETCHANTI/ORPREFETCHOFINSTRUCTIONSCOULDBETOTALLYTRANSPARENTTOTHEEXECUTIONUNITALSO,FORINSTRUCTIONSTHATREQUIREANUMBEROFDATAREFERENCES,THEREQUESTSCOULDBEALMOSTENTIRELYOVERLAPPEDOBVIOUSLY,REQUESTSCOULDNOTBESTREAMEDINTOTHECACHEATTHEHITTHROUGHPUTRATEINDEFINITELYTHEREISALIMITTHISORGANIZATIONSLIMITISIMPOSEDBYTHENUMBEROFMISSESTHATHAVENOTBEENCOMPLETELYPROCESSEDTHATTHECACHEWILLKEEPTRACKOFSIMULTANEOUSLYWITHOUTLOCKUPORGANIZATIONINADDITIONTOTHESTANDARDBLOCKS,THISCACHEORGANIZATIONREQUIRESTHEFOLLOWING1ONEUNRESOLVEDMISSINFORMATION/STATUSHOLDINGREGISTERMSHRFOREACHMISSTHATWILLBEHANDLEDCONCURRENTLYNOW,ACCEPTINGTHEUSEFULNESSOFACACHEBUFFER,ONELOOKSINTOWAYSOFINCREASINGITSEFFECTIVENESS;THATIS,FURTHERDECREASINGTHEEFFECTIVEMEMORYACCESSTIMECONSIDERABLERESEARCHHASBEENDONETOFINETUNEACACHEDESIGNFORVARIOUSREQULRERNENTSPTHISFINETUNINGCONSISTEDOFSELECTINGOPTIMALTOTALCACHEBUFFERSIZE,BLOCKSIZETHENUMBEROFBYTESTOBEREQUESTEDON8101497111/81/0000/008100751981IEEE23ONENWAYCOMPARATOR,INWHICHNISTHENUMBEROFMSHRREGISTERS,FORREGISTERINGHITSONDATAINTRANSITFROMMEMORYANINPUTSTACKTOHOLDTHETOTALNUMBEROFRECEIVEDDATAWORDSPOSSIBLYOUTSTANDINGTHESIZEOFTHISSTACK,CONSEQUENTLY,ISEQUALTOTHEBLOCKSIZEINWORDSTIMESTHENUMBEROFMSHRREGISTERS4MSHRSTATUSUPDATEANDCOLLECTINGNETWORKS5THEAPPROPRIATECONTROLUNITENHANCEMENTTOACCOMMODATE1THROUGH4FIGURE1ISASIMPLIFIEDBLOCKDIAGRAMOFTHECACHEORGANIZATIONASETASSOCIATIVEOPERATIONISASSUMEDINCLUDEDARETHEREQUIREDBLOCKSFORASETASSOCIATIVECACHETAGARRAYSANDCONTROL,CACHEBUFFER,THECENTRALMEMORYINTERFACEBLOCKSMEMORYREQUESTOR,MEMORYRECEIVERANDTHECACHEENHANCEMENTBLOCKSMISSINFOHOLDINGREGISTERS,MISSCOMPARATORANDSTATUSCOLLECTION,INPUTSTACKTHEMISSINFOHOLDINGREGISTERSHOLDALLNECESSARYINFORMATIONTO1HANDLETHECENTRALMEMORYRECEIVEDDATAPROPERLYAND2INFORMTHEMAINCACHECONTROL,THROUGHTHEMISSCOMPARATORANDSTATUSCOLLECTOR,OFALLHITANDOTHERSTATUSOFDATAINTRANSITFROMMEMORYTHEINPUTSTACKISNECESSARYTOLEAVETHEMAINCACHEBUFFERAVAILABLEFOROVERLAPPEDREADSANDWRITESNOTETHATTHISORGANIZATIONALLOWSFORDATAJUSTRECEIVEDFROMMEMORYORINTHEINPUTSTACKTOBESENTIMMEDIATELYTOTHEREQUESTINGCPUUNITSOFCOURSE,THENUMBEROFMSHRREGISTERSISIMPORTANTASWITHSETSIZEBLOCKSPERSETTHEINCREMENTALVALUEDECREASESRAPIDLYWITHTHENUMBEROFREGISTERSTHISISGOOD,BECAUSETHECOSTINCREASESSIGNIFICANTLYWITHTHENUMBEROFREGISTERSFIGURE2PRESENTSAQUALITATIVECURVETHEAVERAGEDELAYTIMEISCAUSEDBYLOCKOUTONOUTSTANDINGMISSESTHISDELAYTIME,OFCOURSE,ISALSODEPENDENTONCACHEINPUTREQUESTANDHITRATESINTHEDEGENERATECASE,1MSHRREGISTEROFREDUCEDSIZEISREQUIRED;2MSHRREGISTERSALLOWFOROVERLAPWHILEONEMISSISOUTSTANDING,BUTSTILLWOULDLOCKUPTHECACHEINPUTONMULTIPLEMISSESOUTSTANDINGOWINGTOCOSTCONSIDERATIONSANDINCREMENTALEFFECTIVENESSGAINEDONINCREASINGTHENUMBEROFMSHRREGISTERS,4REGISTERSAPPEARTOBEOPTIMALFTHENECESSARYINFORMATIONCONTAINEDWITHINONEOFTHESEMSHRREGISTERSINCLUDESTHEFOLLOWINGFIRSTTHECACHEBUFFERADDRESS,ALONGWITHTHEINPUTREQUESTADDRESS,ISREQUIREDTHECACHEBUFFERADDRESSISKEPTTOKNOWWHERETOPLACETHERETURNINGMEMORYDATA;THEINPUTREQUESTADDRESSISSAVEDTODETERMINEIF,ONSUBSEQUENTREQUESTS,THEDATAREQUESTEDISONITSWAYFROMCENTRALMEMORYSECOND,INPUTREQUESTIDENTIFICATIONTAGS,ALONGWITHTHESENDTOCPUSTATUS,ARESTOREDTLIISINFORMATIONPERMITSTHECACHETORETURNTOCPUREQUESTINGUNITSONLYTHEDATAREQUESTEDANDRETURNITWITHITSIDENTIFICATIONTAGTHIRD,ININPUTSTACKINDICATORSAREUSEDTOALLOWFORREADINGDATADIRECTLYFROMTHEINPUTSTACKFOURTH,ACODEFOREXAMPLE,ONEBITPERBYTEFORPARTIALWRITEISHELDFOREACHWORDTOINDICATEWHATBYTESOFTHEWORDHAVEBEENWRITTENTOTHECACHEBUFFERTHISCODECONTROLSTHECACHEBUFFERWRITEUPDATEANDALLOWSDISPENSINGOFDATAFORBUFFERAREASTHATHAVEBEENTOTALLYWRITTENAFTERREQUESTEDTHECACHE,THUS,HASTHECAPABILITYOFPROCESSINGPARTIALWRITEINPUTREQUESTSONTHEFLYWITHOUTPURGINGOFCOURSE,THISPARTIALWRITECODEMAYNOTBEINCORPORATEDIFTHECACHEBLOCKISPURGEDONAPARTIALWRITEREQUESTTOAWORDINABLOCKINTRANSITFROMMEMORYLASTSOMECONTROLINFORMATIONTHEREGISTERCONTAINSVALIDINFORMATIONONLYFORRETURNINGREQUESTEDDATA,BUTNOTFORCACHEBUFFERUPDATEANDTHENUMBEROFWORDSOFTHEBLOCKTHATHAVEBEENRECEIVEDANDWRITTEN,IFREQUIRED,INTOTHECACHEBUFFERISNEEDEDTHEREFORE,EACHMSHRREGISTERCONTAINS1CACHEBUFFERADDRESS2INPUTREQUESTADDRESS3INPUTIDENTIFICATIONTAGSONEPERWORD4SENDTOCPUINDICATORSONEPERWORD5ININPUTSTACKINDICATORSONEPERWORD6PARTIALWRITECODESONEPERWORD7NUMBEROFWORDSOFBLOCKSPROCESSED8VALIDINFORMATIONINDICATOR9OBSOLETEINDICATORINFORMATIONNOTVALIDFORCACHEUPDATEORMSHRHITONDATAINTRANSITOPERATIONTHEOPERATIONCANBESPLITINTOTWOBASICPARTSMEMORYRECEIVER/INPUTSTACKOPERATIONSANDTAGARRAYCONTROLOPERATIONSFORMEMORYRECEIVER/INPUTSTACKOPERATIONS,THEFIELDSOFMSHRINTERROGATEDARETHEFOLLOWING1SENDTOCPUINDICATOR2INPUTIDENTIFICATIONTAGS3CACHEBUFFERADDRESS4PARTIALWRITECODES825OBSOLETEINDICATOR6VALIDINDICATORWHENAWORDISRECEIVEDFROMMEMORY,ITISSENTTOTHECPUREQUESTINGUNITIFTHESENDTOCPUINDICATORISSET;THEAPPROPRIATEIDENTIFICATIONTAGACCOMPANIESTHEDATATHISWORDISALSOWRITTENINTOTHEINPUTSTACKIFTHEWORDSSPACEHASNOTBEENPREVIOUSLYTOTALLYWRITTENINTHECACHEBUFFERORIFMSHRISNOTOBSOLETEINVALIDFORCACHEUPDATETHEWORDSOFDATAAREREMOVEDFROMTHISINPUTSTACKONAFIRSTIN,FIRSTOUTBASISANDAREWRITTENINTOTHECACHEBUFFERUSINGFIELDS3AND4OFCOURSE,MSHRMUSTHOLDVALIDINFORMATIONWHENINTERROGATED,ORANERRORSIGNALWILLBEGENERATEDASLIGHTDIVERSIONISNECESSARYATTHISPOINTTOEXPLAINCACHEDATATAGGINGONAMISS,THECACHEREQUESTSABLOCKOFWORDSALONGWITHEACHWORD,ACACHETAGISSENTTHISTAGPOINTSTOTHEPARTICULARASSIGNEDMSHRANDINDICATESTHEWORDOFTHEBLOCKNOTETHATTHECACHESAVESINMSHRTHEREQUESTINGUNITSIDENTIFICATIONTAGTHISTAGGINGCLOSESTHEREMAININGOPENLINKFORTHEHANDLINGOFDATARETURNEDFROMMEMORYANDREMOVESALLRESTRICTIONSONMEMORYONTHEORDEROFRESPONSESIFAPARTICULARPROCESSOR/MEMORYINTERFACEALLOWSFORADATAWIDTHOFABLOCKOFWORDSFORCACHETOCENTRALMEMORYREQUESTS,THECACHEDATATAGGINGMAYBESIMPLIFIEDBYMERELYPOINTINGTOTHEPARTICULARASSIGNEDMSHRIF,HOWEVER,ALLOTHERDATAPATHSARESTILLONEWORDWIDE,THEMAINOPERATIONSWOULDBEESSENTIALLYUNCHANGEDCONSEQUENTLY,THISEXTENDEDINTERFACEWOULDNOTSIGNIFICANTLYREDUCETHECONTROLCOMPLEXITYORTHEAVERAGELOCKOUTTIMEDELAYPERREQUESTTHEFIELDSOFTHEMSHRUPDATEDDURINGMEMORYRECEIVER/INPUTSTACKOPERATIONSARETHEFOLLOWINGTOTALLYWRITTENORHAVINGANOBSOLETEMSHR,ORISWRITTENINTOTHECACHEBUFFER,THENUMBEROFWORDSPROCESSEDCOUNTERISINCREMENTEDONNUMBEROFWORDSPROCESSEDCOUNTEROVERFLOWALLWORDSFORABLOCKHAVEBEENRECEIVED,THEVALIDORUSEDMSHRINDICATORISCLEAREDFORTAGARRAYCONTROLOPERATIONS,THEFOLLOWINGFIELDSOFMSHRSAREINTERROGATED1INPUTREQUESTADDRESSES2SENDTOCPUINDICATORS3ININPUTSTACKINDICATORS4PARTIALWRITECODES5VALIDINDICATOR6OBSOLETEINDICATORFIELDS1,5,AND6AREUSEDALONGWITHCURRENTINPUTREQUESTADDRESSANDTHENWAYMSHRCOMPARATORTODETERMINEIFTHEREISAHITONPREVIOUSLYMISSEDDATASTILLBEINGHANDLEDPREVIOUSMISSHITFIELDS2,3,AND4PRODUCEONEOFTHEFOLLOWINGSTATESFORTHEPREVIOUSMISSHITPARTIALLYWRITTENPARTIALWRITECODEHASATLEASTONEBITSETTOTALLYWRITTENPARTIALWRITECODEISALLTSININPUTSTACKALREADYASKEDFORSENDTOCPUINDICATORISALREADYSET3NUMBEROFWORDSOFBLOCKPROCESSED12ININPUTSTACKINDICATORSPARTIALWRITECODESFIGURE3INDICATESTHEACTIONSFOLLOWEDBYTHETAGARRAYCONTROLUNDERALLTHEABOVECOMBINATIONSFORAPREVIOUSMISSHITONAMISS,AMSHRISASSIGNED,ANDTHEFOLLOWINGISPERFORMED1VALIDINDICATORSET4VALIDINFORMATIONINDICATORBEINGUSEDINDICATOR2OBSOLETEINDICATORCLEAREDTHEININPUTSTACKINDICATORSARESETWHENTHEDATAWORDISWRITTENINTOTHEINPUTSTACKANDCLEAREDWHENDATAISREMOVEDFROMTHEINPUTSTACKANDWRITTENINTOTHECACHEBUFFERTHEPARTIALWRITECODEISSETTOINDICATETOTALLYWRITTENWHENTHEDATAWORDFROMCENTRALMEMORYINDICATESTHECACHEBUFFERINADDITION,WHENEVERADATAWORDISDISPOSEDOFBECAUSEOFBEING83345CACHEBUFFERADDRESSSAVEDINASSIGNEDMSHRINPUTREQUESTADDRESSSAVEDINASSIGNEDMSHRAPPROPRIATESENDTOCPUINDICATORSETANDOTHERSCLEARED7ALLPARTIALWRITECODESASSOCIATEDWITHASSIGNEDMSHRCLEARED8ALLMSHRSPOINTINGTOSAMECACHEBUFFERADDRESSPURGEDSETPARTIALWRITECODETOALLTSNOTETHATACTIONS5AND6WILLVARYIFTHECACHEFUNCTIONWASAPREFETCHALLSENDTOCPUINDICATORSARECLEARED,ANDNOTAGISSAVED

注意事项

本文(31-Lockup-Free Instruction FetchPrefetch Cache Organization.pdf)为本站会员(baixue100)主动上传,人人文库网仅提供信息存储空间,仅对用户上传内容的表现方式做保护处理,对上载内容本身不做任何修改或编辑。 若此文所含内容侵犯了您的版权或隐私,请立即通知人人文库网(发送邮件至[email protected]或直接QQ联系客服),我们立即给予删除!

温馨提示:如果因为网速或其他原因下载失败请重新下载,重复下载不扣分。

关于我们 - 网站声明 - 网站地图 - 资源地图 - 友情链接 - 网站客服客服 - 联系我们

网站客服QQ:2846424093    人人文库上传用户QQ群:460291265   

[email protected] 2016-2018  renrendoc.com 网站版权所有   南天在线技术支持

经营许可证编号:苏ICP备12009002号-5