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操作系统第十次实验
张焓
1.实验名称：
虚拟内存管理算法
2.实验目的：
1.分析算法设计原理； 2.写出算法伪代码；
3.从算法的执行效率等方面分析算法的性能。
3.实验方法
通过阅读linux内核代码中管理虚拟内存的代码段学习虚拟内存管理算法的原理。
4.实验步骤
(1)mm_struct结构体，定义了每个进程的虚拟存储用户区，首地址在任务结构体中，定义在/include/linux/schedul.h中
structmm_struct { */
spinlock_t page_table_lock;
/* Protects page tables and some counters */
unsignedlong task_size; pgd_t * pgd; atomic_t mm_users; atomic_t mm_count;
/* How many users with user space? */
/* How many references to \/* PTE page table pages */ /* PMD page table pages */ /* number of VMAs */
/* size of task vm space */
/* highest vma end address */
unsignedlong highest_vm_end; structvm_area_struct *mmap; structrb_root mm_rb;
u32 vmacache_seqnum; /* per-thread vmacache */ unsignedlong (*get_unmapped_area) (struct file *filp,
unsignedlong addr, unsignedlong len, unsignedlong pgoff, unsignedlong flags);
/* base of mmap area */
/* list of VMAs */
#ifdef CONFIG_MMU
#endif
unsignedlong mmap_base;
unsignedlong mmap_legacy_base; /* base of mmap area in bottom-up allocations
count as 1) */
atomic_long_t nr_ptes; atomic_long_t nr_pmds; int map_count;
#if CONFIG_PGTABLE_LEVELS > 2 #endif
structrw_semaphore mmap_sem; structlist_head mmlist;
/* List of maybe swapped mm's. These are globally
strung
* together off init_mm.mmlist, and are protected * by mmlist_lock */
unsignedlong hiwater_rss; /* High-watermark of RSS usage */ unsignedlong hiwater_vm; /* High-water virtual memory usage */ unsignedlong total_vm; unsignedlong locked_vm; unsignedlong pinned_vm; unsignedlong data_vm; unsignedlong exec_vm; unsignedlong stack_vm; unsignedlong def_flags;
unsignedlong start_code, end_code, start_data, end_data; unsignedlong start_brk, brk, start_stack;
unsignedlong arg_start, arg_end, env_start, env_end;
unsignedlong saved_auxv[AT_VECTOR_SIZE]; /* for /proc/PID/auxv */ /*
* Special counters, in some configurations protected by the * page_table_lock, in other configurations by being atomic. */
structmm_rss_stat rss_stat; structlinux_binfmt *binfmt; cpumask_var_t cpu_vm_mask_var;
/* Architecture-specific MM context */ mm_context_t context;
unsignedlong flags; /* Must use atomic bitops to access the bits */ structcore_state *core_state; /* coredumping support */ spinlock_t
ioctx_lock;
/* Total pages mapped */
/* Pages that have PG_mlocked set */ /* Refcount permanently increased */ /* VM_WRITE & ~VM_SHARED & ~VM_STACK */ /* VM_EXEC & ~VM_WRITE & ~VM_STACK */ /* VM_STACK */
#ifdef CONFIG_AIO
struct kioctx_table __rcu *ioctx_table;
#endif
#ifdef CONFIG_MEMCG
/* store ref to file /proc/
struct mmu_notifier_mm *mmu_notifier_mm; /*
* \ * user/owner of this mm. All of the following must be true in * order for it to be changed: *
* current == mm->owner * current->mm != mm * new_owner->mm == mm
* new_owner->alloc_lock is held */
struct task_struct __rcu *owner;
#endif
#ifdef CONFIG_MMU_NOTIFIER #endif
#ifdefined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
pgtable_t pmd_huge_pte; /* protected by page_table_lock */ #endif
#ifdef CONFIG_CPUMASK_OFFSTACK
struct cpumask cpumask_allocation; #endif
#ifdef CONFIG_NUMA_BALANCING
/* numa_scan_seq prevents two threads setting pte_numa */ int numa_scan_seq;
/* Restart point for scanning and setting pte_numa */ unsignedlong numa_scan_offset; /*
* numa_next_scan is the next time that the PTEs will be marked * pte_numa. NUMA hinting faults will gather statistics and migrate * pages to new nodes if necessary. */
unsignedlong numa_next_scan;
#endif
#ifdefined(CONFIG_NUMA_BALANCING) || defined(CONFIG_COMPACTION)
/*
* An operation with batched TLB flushing is going on. Anything that * can move process memory needs to flush the TLB when moving a