Virt, res, SHR, virtual memory and physical memory)

Virt:

1Process"Required"Virtual Memory size, including the database used by the process,Code, Data, andMalloc,NewAllocated heap space and allocated stack space;

2If the process has a new application10 MBMemory, but actually only used1 MB, It will increase10 MBInstead of the actual1 MBUsage.

3,Virt = swap + Res

Res:

1The memory size currently used by the process, includingMalloc,NewAllocated heap space and allocated stack space, but not includingSwap outQuantity;

2, Including sharing of other processes;

3If you apply10 MBMemory, actually used1 MB, It only grows1 MB, AndVirtOpposite;

4Only the memory occupied by the loaded library files is counted.

5,Res = code + Data

SHR:

1In addition to the shared memory of its own processes, it also includes the shared memory of other processes;

2, Although the process only uses several shared library functions, it contains the size of the entire shared library;

3Formula for Calculating the physical memory occupied by a process:Res-SHR;

4,Swap outIt will be downgraded.

Example

# Include <iostream>

 

Int main ()

{

Char * P = new char [1024*1024*512];

Getchar ();

Return 0;

}

Top:

PID user PR Ni virt res shr s % CPU % mem time + command

401 hhhhh 17 0 523 M 916 s 792 0.0. 00./main

Original article:

Http://blog.csdn.net/huyiyang2010/article/details/7815491