Memory Management Scheme First fit, best fit worst fit

Problem No: 09

Name of the problem: Memory management scheme-Worst fit

Theory: It’s a method to map segments to holes (spaces) in virtual memory. It selects the largest available hole in memory that can fit a needed segment, so as to leave a large hole for other segments.

Code:          

                    

#include<bits/stdc++.h>

using namespace std;

#define max 25

int main()

{

    int i,j,b[max],f[max],frag[max],highest,nb,nf,temp;

    static int bf[max],ff[max];

    cout<<"Memory management scheme - worst fit";

    cout<<"enter the number of blocks :";

    cin>>nb;

    cout<<"enter the number of files :";

    cin>>nf;

    cout<<endl<<"enter the size of the blocks :"<<endl;

    for(i=1;i<nb+1;i++)

    {

        cout<<"block "<<i<<":";

        cin>>b[i];

    }

        cout<<endl<<"enter the size of the files :"<<endl;

    for(i=1;i<nf+1;i++)

    {

        cout<<"file "<<i<<":";

        cin>>f[i];

    }

 cout<<"file no:\tfile size\tblock no\tblock size\tfragment"<<endl;

    for(i=1;i<=nf;i++)

    {highest=0;

        for(j=1;j<=nb;j++)

        {

            if(bf[j]!=1)

            {

                temp=b[j]-f[i];

                if(temp>=highest)

                    {

                        ff[i]=j;

                        highest=temp;

                    }}}

        frag[i]=highest;

        bf[ff[i]]=1;

          cout<<i<<"\t\t"<<f[i]<<"\t\t"<<ff[i]<<"\t\t"<<b[ff[i]]<<"\t\t"<<frag[i]<<endl;

    }}

Problem No: 10

Name of the problem: Memory management scheme-Best Fit

Theory: In the first fit, the partition is allocated which is first sufficient from the top of Main Memory.

Code:        

#include<bits/stdc++.h>

using namespace std;

#define max 25

int main()

{

    int i,j,b[max],f[max],frag[max],lowest,nb,nf,temp;

    static int bf[max],ff[max];

    cout<<"Memory management scheme - Best fit";

    cout<<"enter the number of blocks :";

    cin>>nb;

    cout<<"enter the number of files :";

    cin>>nf;

    cout<<endl<<"enter the size of the blocks :"<<endl;

    for(i=1;i<nb+1;i++)

    {

        cout<<"block "<<i<<":";

        cin>>b[i];

    }

        cout<<endl<<"enter the size of the files :"<<endl;

    for(i=1;i<nf+1;i++)

    {cout<<"file "<<i<<":";

        cin>>f[i];

    }

 cout<<"file no:\tfile size\tblock no\tblock size\tfragment"<<endl;

    for(i=1;i<=nf;i++)

    {lowest=1000;

        for(j=1;j<=nb;j++)

        {

            if(bf[j]!=1)

            {

                temp=b[j]-f[i];

                if(temp>=0)

                    {

                        if(temp<lowest)

                        {

                          ff[i]=j;

                        lowest=temp;

                        } } } }

        frag[i]=lowest;

        bf[ff[i]]=1;

          cout<<i<<"\t\t"<<f[i]<<"\t\t"<<ff[i]<<"\t\t"<<b[ff[i]]<<"\t\t"<<frag[i]<<endl;

    }}

Problem No: 11

Name of the problem: Memory management scheme-First Fit

Theory: There may be many holes in the memory, so the operating system, to reduce the amount of time it spends analyzing the available spaces, begins at the start of primary memory and allocates memory from the first hole it encounters large enough to satisfy the request.

Code:          

                    

#include<bits/stdc++.h>

using namespace std;

#define max 25

int main()

{

    int i,j,b[max],f[max],frag[max],nb,nf,temp;

    static int bf[max],ff[max];

    cout<<"Memory management scheme - First fit \n";

    cout<<"enter the number of blocks: ";

    cin>>nb;

    cout<<"enter the number of files";

    cin>>nf;

    cout<<"enter the size of the blocks :"<<endl;

    for(i=1;i<nb+1;i++)

    {

        cout<<"block "<<i<<":";

        cin>>b[i];

    }

        cout<<"enter the size of the files :"<<endl;

    for(i=1;i<nf+1;i++)

    {

        cout<<"file "<<i<<":";

        cin>>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)

                    {

                        ff[i]=j;

                        break;

                    }}}

        frag[i]=temp;

        bf[ff[i]]=1;

    }

    cout<<"file no:\tfile size\tblock no\tblock size\tfragment"<<endl;

    for(i=1;i<=nf;i++)

    {cout<<i<<"\t\t"<<f[i]<<"\t\t"<<ff[i]<<"\t\t"<<b[ff[i]]<<"\t\t"<<frag[i]<<endl;

    }}