linux中的map怎么清空,linux内存优化一文中查看进程mem_map 的实现

Dear 丶 2023-01-22 04:54 2阅读 0赞

最近有同事在读<>一文,我也看了下,写得不错,满通俗易懂的,但是其中关于

进程mem map 显示的东西,好象没提供,我搜了下只找到个显示全部mem map 的,于是自己写了一个,

虽然代码很小,但写+调试也花了半天时间，废话少说 ,具体代码如下:

mem\_map.c :

\#include

\#define liuprintk printk

unsigned short \*proc\_memmap;

int msize;

struct page \*vm\_get\_page(struct vm\_area\_struct \*vma, unsigned long addr, pte\_t pte)

unsigned long pfn = pte\_pfn(pte);

if (unlikely(vma->vm\_flags & (VM\_PFNMAP|VM\_MIXEDMAP))) \{

liuprintk("\\nliutest: has pure pfn \\n");

\#if 0

if (vma->vm\_flags & VM\_MIXEDMAP) \{

if (!pfn\_valid(pfn))

return NULL; /\* invalid page \*/

goto out;

\} else \{

unsigned long off;

off = (addr - vma->vm\_start) >> PAGE\_SHIFT; /\* VM\_PFNMAP 的处理\*/

if (pfn == vma->vm\_pgoff + off)

return NULL;

if (!is\_cow\_mapping(vma->vm\_flags))

return NULL;

\#endif

//out:

return pfn\_to\_page(pfn);

static inline void

show\_one\_pte(struct mm\_struct \*mm, pte\_t \*src\_pte, struct vm\_area\_struct \*vma,

unsigned long addr) /\* liunote linux pte \*/

unsigned long vm\_flags = vma->vm\_flags;

pte\_t pte = \*src\_pte; /\* get pte val \*/

struct page \*page;

int pm\_index;

if (unlikely(!pte\_present(pte))) \{

if (!pte\_file(pte)) \{ /\* liunote anymous page \*/

/\* liunote can do it best \*/

goto out\_show\_pte;

page = vm\_get\_page(vma, addr, pte); /\* 是normal page \*/

if (page) \{

/\* liunote get share proc num \*/

pm\_index = (addr - vma->vm\_start) /PAGE\_SIZE;

proc\_memmap\[pm\_index\] = atomic\_read(&(page)->\_mapcount);

//printk("liutest pmd\_index=0x%X,addr= 0x%X,vmstart=0x%X:,mapcount=%d", pm\_index ,addr , vma->vm\_start,atomic\_read(&(page)->\_mapcount));

if (proc\_memmap\[pm\_index\]==0)\{

proc\_memmap\[pm\_index\] =1;

out\_show\_pte:

return;

static int show\_ptes(struct mm\_struct \*mm, pmd\_t \*pmd, struct vm\_area\_struct \*vma,

unsigned long addr, unsigned long end)

pte\_t \*pte;

spinlock\_t \*ptl;

/\* liunote below dst\_pte is linux pte ??? \*/

pte = pte\_offset\_map\_nested(pmd, addr);

ptl = pte\_lockptr(mm, pmd);

/\* liunote need lock to read it ??? \*/

/\* spin\_lock\_nested(ptl, SINGLE\_DEPTH\_NESTING);\*/

do \{

if (pte\_none(\*pte)) \{ /\* src\_pte = 0 \*/

//liuprintk("\\nliutest: bad pte=0x%X,addr=0x%X\\n",pte,addr);

continue;

show\_one\_pte(mm, pte, vma, addr);

\} while (pte++, addr += PAGE\_SIZE, addr != end);

/\* spin\_unlock(ptl); \*/

return 0;

static inline int show\_pmds(struct mm\_struct \*mm, pud\_t \*pud, struct vm\_area\_struct \*vma,

unsigned long addr, unsigned long end)

pmd\_t \* pmd;

unsigned long next;

pmd = pmd\_offset(pud, addr);

do \{

next = pmd\_addr\_end(addr, end);

if (pmd\_none\_or\_clear\_bad(pmd))\{

liuprintk("\\nliutest: bad pmd=0x%X,addr=0x%X\\n",pmd,addr);

continue;

if (show\_ptes(mm, pmd,

vma, addr, next))

return -ENOMEM;

\} while (pmd++, addr = next, addr != end);

return 0;

static inline int show\_puds(struct mm\_struct \*mm, pgd\_t \*pgd, struct vm\_area\_struct \*vma,

unsigned long addr, unsigned long end)

pud\_t \*pud ;

unsigned long next;

pud = pud\_offset(pgd, addr);

do \{

next = pud\_addr\_end(addr, end);

if (pud\_none\_or\_clear\_bad(pud))\{

liuprintk("\\n liutest: bad pud=0x%X,addr=0x%X\\n",pud,addr);

continue;

if (show\_pmds(mm, pud,

vma, addr, next))

return -ENOMEM;

\} while (pud++, addr = next, addr != end);

return 0;

// liuadd for print pte

int show\_pages(struct mm\_struct \* mm, struct vm\_area\_struct \*vma)

pgd\_t \*pgd;

unsigned long next;

unsigned long addr = vma->vm\_start;

unsigned long end = vma->vm\_end;

int ret,i;

int pages =0;

// according vm size ,malloc proc memmap

msize = end-addr;

msize = (msize & (PAGE\_SIZE-1)) ? (msize+PAGE\_SIZE)/PAGE\_SIZE : msize/PAGE\_SIZE;

liuprintk("\\nliutest: msize =0x%X, PAGE\_SIZE=0x%X\\n",msize,PAGE\_SIZE);

proc\_memmap = kmalloc( msize\*(sizeof(unsigned short)),GFP\_KERNEL);

if(proc\_memmap == NULL)\{

printk("\\n liutest : proc mem map alloc fail \\n");

return 1;

for(i=0; i

proc\_memmap\[i\] = 0;

/\*

if (!(vma->vm\_flags & (VM\_HUGETLB|VM\_NONLINEAR|VM\_PFNMAP|VM\_INSERTPAGE))) \{

if (!vma->anon\_vma)

return 0;

\*/

ret = 0;

pgd = pgd\_offset(mm, addr);

do \{

next = pgd\_addr\_end(addr, end);

if (pgd\_none\_or\_clear\_bad(pgd))\{

liuprintk("\\nliutest: bad pgd=0x%X,addr=0x%X\\n",pgd,addr);

continue;

if (unlikely(show\_puds(mm, pgd, vma, addr, next))) \{

ret = -ENOMEM;

break;

\} while (pgd++, addr = next, addr != end);

\#if 1

for(i=0; i

if(proc\_memmap\[i\])

pages++;

printk("\\nliutest: this vm area has pages =0x%X\\n",pages);

// free memmap

kfree(proc\_memmap);

\#endif

return ret;

\#undef liuprintk

上面mem\_map.c 文件加到proc 目录下

然后在task\_mmu.c show\_map\_vma 函数末尾加上:

show\_pages(vma->vm\_mm, vma);

proc 下面Makefile 加上 mem\_map.o

代码有点乱,不过测试过还行,内容全在proc\_memmap 数组里，大小为msize,

可根据自己喜好显示从proc 输出

下面是测试busybox内存情况

Cd proc

Cd 1

Cat maps显示如下:

00008000-00100000 r-xp 00000000 00:01 60         /bin/busybox

Pages:0xF8-0x4D      ( F8页,实际占用4D页，下面是实际页内存引用情况)

0x0002 0x0002 0x0000 0x0000 0x0002 0x0002 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000

0x0000 0x0000 0x0000 0x0000 0x0000 0x0001 0x0001 0x0001 0x0001 0x0001 0x0001 0x0001 0x0001 0x0001 0x0001 0x0001 0x0001 0x0001 0x0001 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0001 0x0000 0x0001 0x0001 0x0000 0x0000 0x0000

0x0000 0x0000 0x0000 0x0000 0x0002 0x0000 0x0002 0x0000 0x0000 0x0002 0x0002 0x0002 0x0002 0x0000 0x0000 0x0000 0x0000 0x0001 0x0001 0x0001 0x0001 0x0000 0x0000 0x0000 0x0001 0x0001 0x0000 0x0000 0x0001 0x0001 0x0001 0x0001

0x0001 0x0001 0x0002 0x0002 0x0002 0x0002 0x0002 0x0001 0x0002 0x0002 0x0001 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0001 0x0002 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000

0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0001 0x0002 0x0000 0x0000 0x0002 0x0002 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0002 0x0002

0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0002 0x0001 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0001 0x0000 0x0000 0x0000 0x0002 0x0000 0x0000 0x0000 0x0000 0x0000

0x0000 0x0002 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0002 0x0001 0x0002 0x0000 0x0002 0x0000 0x0001 0x0001 0x0000 0x0000 0x0000

0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0001 0x0000 0x0000 0x0002 0x0002 0x0000 0x0002 0x0002 0x0000 0x0000 0x0002 0x0000 0x0001 0x0001 0x0001 0x0001 0x0000 0x0000

00107000-00108000 rw-p 000f7000 00:01 60         /bin/busybox

Pages:0x1-0x1

0x0001

00108000-0012e000 rw-p 00108000 00:00 0          \[heap\]

Pages:0x26-0x6

0x0001 0x0001 0x0000 0x0001 0x0001 0x0001 0x0001 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000

0x0000 0x0000 0x0000 0x0000 0x0000 0x0000

40000000-40001000 rw-p 40000000 00:00 0

Pages:0x1-0x1

0x0001

be844000-be859000 rw-p befeb000 00:00 0          \[stack\]

Pages:0x15-0x2     (这是栈，有15页,实际占用2页，下面也可以看出，占了倒数的两页符合栈特性,)

0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0001 0x0001