what is page fault how can i reduce it

#include <vector>
using namespace std;


#include <stdio.h>
int main(int argc, char* argv[])
{
register unsigned  int size=0;
register unsigned  int u, v;
FILE *file;
vector<unsigned  int> arr;//vector to store unsigned  integers from file

//-----file read operation------
file=fopen(argv[1],"r");


    while(!feof(file))
        {
        ++size;
        arr.resize(size);
        fscanf(file,"%u\n",&arr[size-1]);

        }
//------end of file read operation---

//-------actual calucation-----------
vector<unsigned  int> b;

vector<unsigned  int> p(arr.size());

  if (!(arr.empty()))
  {

	{

	b.push_back(0);

	for (size_t i = 1; i < arr.size(); i++)
        {

		if (arr[b.back()] < arr[i])
                {
			p[i] = b.back();
			b.push_back(i);
			continue;
		}
		for (u = 0, v = b.size()-1; u < v;)
                {
			unsigned  int c = (u + v) / 2;
			if (arr[b[c]] < arr[i]) u=c+1; else v=c;
		}

		if (arr[i] < arr[b[u]])
                {
			if (u > 0) p[i] = b[u-1];
			b[u] = i;
		}
	if(i>arr.size())break;
	}

	for (u = b.size(), v = b.back(); u--; v = p[v]) b[u] = v;
 }
}
//--------end of actual calucation----

//-----printing output---------
printf("%u\n", b.size());

	return 0;
}

#if defined(WIN32)

    #pragma warning (disable: 4290)    // A function is declared using exception specification, which Visual C++ accepts but does not implement.
    #pragma warning (disable: 4996)    // The POSIX name for this item is deprecated

    typedef INT8    int8_t;
    typedef UINT8   uint8_t;
    typedef INT16   int16_t;
    typedef UINT16  uint16_t;
    typedef INT32   int32_t;
    typedef UINT32  uint32_t;
    typedef INT64   int64_t;
    typedef UINT64  uint64_t;
#else

const uint64_t GetFileSize(const char* pszPath)
{
    if ( (NULL == pszPath) || (0 == strlen(pszPath)) )
        throw exception("Invalid path!");

    uint64_t nSize = 0;

#ifdef WIN32

    HANDLE hFile = ::CreateFileA(pszPath, 0, FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);

    if (INVALID_HANDLE_VALUE == hFile)
        exception("Could not open file");

    try
    {
        BY_HANDLE_FILE_INFORMATION fiInfo;
        if (!::GetFileInformationByHandle(hFile, &fiInfo))
            exception("GetFileInformationByHandle failed");

        nSize = (((uint64_t)fiInfo.nFileSizeHigh) << 32) + (uint64_t)fiInfo.nFileSizeLow;
    }
    catch (...)
    {
        ::CloseHandle(hFile);
        throw;
    }

    ::CloseHandle(hFile);

#else

    struct stat st;
    if (0 != stat(pszPath, &st))
        exception("stat failed");

    nSize = static_cast<uint64_t>(st.st_size);

#endif

    return nSize;
}