HugePages on Linux What It is and What It Is Not (文档 ID 361323.1)

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1、APPLIESTO:LinuxOS-VersionEnterpriseLinux3.0toOracleLinux6.5withUnbreakableEnterpriseKernel[3.8.13][ReleaseRHEL3toOL6U5]OracleDatabase-EnterpriseEditionIBM:LinuxonSystemzLinuxx86IBM:LinuxonPOWERSystemsIBMS/390BasedLinux(31-bit)Linuxx86-64LinuxItanium***Checkedforrelevanceon20-May-2

2、013*** PURPOSEThisdocumentdescribestheHugePagesfeatureintheLinuxkernelavailablefor32-bitand64-bitarchitectures.TherehasbeensomeconfusionamongthetermsandusesrelatedtoHugePages.Thisdocumentshouldclarifythemisconceptionsaboutthefeature.SCOPEInformationinthisdocumentisusefulforLinuxsy

3、stemadministratorsandOracledatabaseadministratorsworkingwithsystemadministrators.ThisdocumentcoversinformationaboutHugePagesconceptthatappliestoverylargememorysystemsfor32-bitand64-bitarchitecturesincludingsomeconfigurationinformationandreferences.DETAILSIntroductionHugePagesisafe

4、atureintegratedintotheLinuxkernelwithrelease2.6.Thisfeaturebasicallyprovidesthealternativetothe4Kpagesize(16KforIA64)providingbiggerpages.RegardingtheHugePages,therearesomeothersimilartermsthatarebeingusedlike,hugetlb,hugetlbfs.BeforeproceedingintothedetailsofHugePages,seethedefin

5、itionsbelow:·PageTable:Apagetableisthedatastructureofavirtualmemorysysteminanoperatingsystemtostorethemappingbetweenvirtualaddressesandphysicaladdresses.Thismeansthatonavirtualmemorysystem,thememoryisaccessedbyfirstaccessingapagetableandthenaccessingtheactualmemorylocationimplicit

6、ly.·TLB: ATranslationLookasideBuffer(TLB)isabuffer(orcache)inaCPUthatcontainspartsofthepagetable.Thisisafixedsizebufferbeingusedtodovirtualaddresstranslationfaster.·hugetlb: ThisisanentryintheTLBthatpointstoaHugePage(alarge/bigpagelargerthanregular4Kandpredefinedinsize).HugePagesa

7、reimplementedviahugetlbentries,i.e.wecansaythataHugePageishandledbya"hugetlbpageentry".The'hugetlb"termisalso(andmostly)usedsynonymouslywithaHugePage(See Note261889.1).Inthisdocumenttheterm"HugePage"isgoingtobeusedbutkeepinmindthatmostly"hugetlb"referstothesameconcept.·hugetlbfs: 

8、Thisisanewin-memoryfilesystemlike