Linux内存管理模拟器.rar_Linux C语言_二级页表模拟_内存分页管理_内存管理模拟_数学建模

/************************************************************************/ /* */ /* The 3rd experiment of OS course */ /* */ /* LUO Pengkui (SS31,2003010655) */ /* */ /* 2005-12-19 */ /* */ /* */ /************************************************************************/ #include <stdio.h> #include <time.h> #include <stdlib.h> /************************************************************************/ struct Mem_page { int flag; int next; int pre; int m_page; int pg_index; } mem_page[1024]={{0,0,0,0,0}}; int swap_page[1024]={0}; unsigned long dir[1024]={0}; unsigned long page[1024][1024]={0}; int swapout,nrout,nrin; int head=0; int tail=1023; /************************************************************************/ int swap_out() { int i; for(i=0;i<1024;i++) if (!swap_page[i]) break; if (i>=1024) printf("ERROR OCCURS!\n"); else { swap_page[i]=1; page[mem_page[tail].pg_index][mem_page[tail].m_page]=(i<<22)|2; nrout=i; } return i; } void visit_page(int i) { if (i!=head) { mem_page[mem_page[i].pre].next=mem_page[i].next; mem_page[i].next=head; mem_page[head].pre=i; if (i==tail) tail=mem_page[i].pre; head=i; } head=i; } unsigned long get_freepage(int pg_index,int m_page,int* pswap) { unsigned long i; if(mem_page[tail].flag) *pswap=swap_out(); else *pswap=-1; i=tail; swapout=tail; mem_page[tail].flag=1; mem_page[tail].pg_index=pg_index; mem_page[tail].m_page=m_page; visit_page(tail); return i; } unsigned long genRan() { unsigned long res=0; for (int i=10; i<=32; i++) res = res=(res<<1)+rand()%2; return res; } /************************************************************************/ void main() { FILE * f; int i,j,k; unsigned long vAddr; unsigned long pgd,pte; int m_index=0; int m_page=0; int pg_index=0; int nr; /* initialization */ for(i=0;i<1024;i++) { mem_page[i].next=i+1; mem_page[i].pre=i-1; } srand((unsigned)time( NULL)); f=fopen("out.txt","w"); fprintf(f,"RefAddr \tPgd \t\tPte \t\tSwap_nr \n"); for(i=0;i<8192;i++) { vAddr=genRan(); m_index=vAddr>>22; m_page=(vAddr>>12) & 1023; if (!(dir[m_index]&1)) /* if last bit of m_index==0, table misses */ { pgd = (m_index<<22) | 1; dir[m_index]=pgd; } pgd=dir[m_index]; pg_index=pgd>>22; j=(page[pg_index][m_page]<<30) >>30; /* last 2 bits of page */ k=page[pg_index][m_page]>>22; /* first 10 bits */ switch(j) { case 2: /* page on the swap page */ pte=(get_freepage(pg_index,m_page,&nr)<<22)|1; page[pg_index][m_page]=pte; swap_page[k]=0; nrin=k; break; case 0: /* no mapping mem */ pte=(get_freepage(pg_index,m_page,&nr)<<22)|1; page[pg_index][m_page]=pte; break; default: /* ==1, already point to a page */ pte=page[pg_index][m_page]; visit_page(k); nr=-1; } if (nr==-1) fprintf(f,"%8X \t%8X \t%8X \t\t-1\n",vAddr,pgd,pte); else fprintf(f,"%8X \t%8X \t%8X \t%8X\n",vAddr,pgd,pte,nr); } fclose(f); } /************************************************************************/