OS Memory Management Scheme Best Fit C Program

Operating Systems Lab Manual / OS Memory Management Scheme Best Fit C Program

Program Name	Write a C Program for OS Memory Management Scheme Best Fit
Theory	The operating system manages memory allocation. The operating system divides the memory into several fixed-sized partitions and each partition may contain exactly one process. When a partition is free, a process is selected from the input queue and is loaded into the free partition. When the process terminates, the partition becomes available for another process. Operating system keeps a table indicating which parts of memory are available and which are occupied. Finally, when a process arrives and needs memory, a memory section large enough for this process is provided. When it is time to load or swap a process into main memory, and if there is more than one free block of memory of sufficient size, then the operating system must decide which free block to allocate. Best-Fit chooses the block that is closest in size to the request.
Program	#include<stdio.h> #include<conio.h> #define max 25 void main() { int fragment[max],b[max],f[max],i,j,nb,nf,temp,lowest=10000; static int bf[max],ff[max]; printf("\nEnter number of blocks:"); scanf("%d",&nb); printf("\nEnter number of files:"); scanf("%d",&nf); printf("\nEnter size of the blocks:-\n"); for(i=1;i<=nb;i++) { printf("Block %d:",i); scanf("%d",&b[i]); } printf("Enter size of the files :\n"); for(i=1;i<=nf;i++) { printf("File %d:",i); scanf("%d",&f[i]); } for(i=1;i<=nf;i++) { for(j=1;j<=nb;j++) { if(bf[j]!=1) { temp=b[j]-f[i]; if(temp>=0) if(lowest>temp) { ff[i]=j; lowest=temp; } } } fragment[i]=lowest; bf[ff[i]]=1; lowest=10000; } printf("\n File No\t File Size \t Block No\t Block Size\t Fragment"); for(i=1;i<=nf && ff[i]!=0;i++) printf("\n%d\t\t%d\t\t%d\t\t%d\t\t%d",i,f[i],ff[i],b[ff[i]],fragment[i]); }
Input	Enter number of blocks:3 Enter number of files:2 Enter size of the blocks:- Block 1:5 Block 2:2 Block 3:7 Enter size of the files : File 1:1 File 2:4
Output	File No File Size Block No Block Size Fragment 1 1 2 2 1 2

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