9.+Linux+Memory+Management.ppt

高级操作系统陈燕晖2006-7,LinuxMemoryManagement,高级操作系统陈燕晖2006-7,1.NUMA.;structfree_areastructlist_headfree_list;unsignedlongnr_free;,高级操作系统陈燕晖2006-7,4.APIforpageallocator,alloc_page(gfp_mask)Allocateasinglepageandreturnapointertoitspagestructurealloc_pages(gfp_mask,order)Allocate2orderpagesandreturnapointertothefirstpagespagestructure_get_free_page(gfp_mask)Allocateasinglepageandreturnapointertoitslogicaladdress_get_free_pages(gfp_mask,order)Allocate2orderpagesandreturnapointertothefirstpageslogicaladdressget_zeroed_page(gfp_mask)Allocateasinglepage,zeroitscontents,andreturnapointertoitslogicaladdress,高级操作系统陈燕晖2006-7,void_free_pages(structpage*page,unsignedintorder)voidfree_pages(unsignedlongaddr,unsignedintorder)voidfree_page(unsignedlongaddr)EXAMPLE:unsignedlongpage;page=_get_free_pages(GFP_KERNEL,3);if(!page)/*insufficientmemory:youmusthandlethiserror!*/returnENOMEM;/*pageisnowtheaddressofthefirstofeightcontiguouspages.*/free_pages(page,3);,高级操作系统陈燕晖2006-7,5hot/*pagesinpool*/intlow;inthigh;intbatch;structlist_headlist;/*pagelist*/;structper_cpu_pagesetstructper_cpu_pagespcp2;/*0:forhotpages1:forcoldpages*/._cacheline_aligned_in_smp;,Thekernelmonitorsthesizeoftheboththehotandcoldcachesbyusingtwowatermarks:ifthenumberofpageframesfallsbelowthelowwatermark,thekernelreplenishesthepropercachebyallocatingbatchsinglepageframesfromthebuddysystem;ifthenumberofpageframesrisesabovethehighwatermark,thekernelreleasestothebuddysystembatchpageframesinthecache,高级操作系统陈燕晖2006-7,vmalloc/vfree,Forinfrequentmemoryrequestssometimesitmakessensetoallocatenoncontiguousmemoryareasnoncontiguous,page-basedallocatorusedforlargishallocationsnotsuitableforallmemoryrequestsenoughpagesbutnotcontiguous?modifieskernelpagetablemakepageslookvirtuallycontiguousallocatedintopGBafterphysicalmemmaponasystemwith1GB,896MBplaces4KBredzonesaroundallocationsvmlistlinkedlistofvm_structdescriptorsdescriptorsallocatedusingkmalloc(),高级操作系统陈燕晖2006-7,void*_vmalloc(unsignedlongsize,intgfp_mask,pgprot_tprot)structvm_struct*area;structpage*pages;unsignedintnr_pages,array_size,i;.area=get_vm_area(size,VM_ALLOC);.nr_pages=sizePAGE_SHIFT;array_size=(nr_pages*sizeof(structpage*);area-nr_pages=nr_pages;area-pages=pages=kmalloc(array_size,(gfp_mask.if(map_vm_area(area,prot,&pages).,vmalloc(/mm/vmalloc.c),Getfreeaddressspace(linearaddress),Allocateonepageframefrombuddysystem,A