Linux system: View system Run status, command W

Original: http://www.cnblogs.com/ggjucheng/archive/2012/01/08/2316399.html

Introduction

The top command is a common performance analysis tool under Linux that shows the resource usage of individual processes in the system in real time, similar to the Task Manager for Windows.

Top display system current process and other conditions, is a dynamic display process, that is, you can continue to refresh the current state through the user keys. If the command is executed in the foreground, it will monopolize the foreground until the user terminates the program. More accurately, the top command provides real-time status monitoring of the system's processor. It will display the most "sensitive" CPU in the system Task List. This command can be used by CPU. Memory usage and execution time to sort tasks, and many of the features of the command can be set through interactive commands or in personal customization files.

Here is a detailed description of how it is used.

parameter meaning

Top-01:06:Up1:22,1 user, load average:0.06,0.60,0.48
Tasks:Total,1 Running,Sleeping,0 stopped,0 Zombie
Cpu (s):0.3% us,1.0% Sy,0.0% ni,98.7% ID,0.0% WA,0.0% Hi,0.0% si
mem:191272k Total, 173656k used, 17616k free, 22052k buffers
swap:192772k Total, 0k used, 192772k free, 123988k cached

PID USER PR NI VIRT RES SHR S%cpu%MEM time+ COMMAND
1379 Root160797624561980 S0.71.30:11.03 sshd
14704 Root1602128980796 R0.70.50:02.72 Top
1 root1601992632544 S0.00.3 0:00.90 init 
 2 root 34 19 0 0 0 S 0.0 0.0 0:00.00 ksoftirqd/0 
 3 root RT 0 0 0 0 S 0.0 0.0 0:00.00 Watchdog/0              

The first five elements of the statistical information area are the statistical information of the whole system. The first line is the task queue information, with the execution result of the uptime command. The contents are as follows:

(a):    Current time
1:    system run time, format last: minutes
1 user Current number of users logged on
0.48 system load, which is the average length of the task queue. The three values were 1 minutes, 5 minutes, and 15 minutes ago to the present average.

The second to third behavior process and CPU information. When there are multiple CPUs, the content may be more than two lines. The contents are as follows:

0.3% US user space consumes CPU percentage 1.0% SY core space consumes CPU percentage 0.0% process in NI user process space has changed priority CPU percentage ID idle CPU percent 0.0% wa Wait for the input output CPU time percentage 0.0%Hi: Hardware CPU interrupt consumption percent 0.0%si: Soft interrupt occupancy percent 0.0%st: VM occupancy percentage 

The last two behavior memory information. The contents are as follows:

Mem:
    Total physical memory of 191272k
    Total physical memory used by 173656k used
17616k    free Memory Total
    The amount of memory that 22052k buffers uses as the kernel cache

    Total Swap Area 192772k
    Total swap area used by 0k used
192772k    free Swap area total
123988k cached    Buffer The total amount of swap, in-memory content is swapped out to the swap area, and then swapped into memory, but the used swap area has not been overwritten, the value is that the content already exists in the memory of the swap area, the corresponding memory will be swapped out when the swap area can no longer write.

The details of each process are shown below the process information area statistics area. Let's start by understanding the meaning of the columns.

Ordinal  column name    meaning
A    PID     process ID
b    PPID    parent Process ID
C    ruser   Real user name
D    UID     process owner's user ID
E    username of user process Owner
   Group Name of the F group Process owner
     The terminal name of the G TTY boot process. Processes that are not started from the terminal are displayed as?
H    PR      -Priority
I    NI nice      value. Negative values indicate high priority, positive values indicate low priority
       The last CPU used by J P is meaningful only in a multi-CPU environment
K    %cpu    CPU time consumption percentage last updated to current
    The total CPU time, in seconds, used by the timing process
   The total CPU time used by the M time+ process, in units 1/100 seconds
N    The percentage of physical memory used by the%MEM process
o    The total amount of virtual memory used by the VIRT process, in kilobytes. Virt=swap+res
The P    swap    process uses the size of the virtual memory, which is swapped out, in kilobytes.
The    size of the     physical memory, in kilobytes, that the Q RES process uses and has not been swapped out. Res=code+data
R    Code    executable code occupies the physical memory size, in kilobytes
The    amount of physical memory that is used outside of the S data executable code (data segment + stack), in kilobytes
T    SHR     shared memory size, in kilobytes
U    nflt    page Error count
V    NDRT The    number of pages that have been modified in the last write to now.
W    S       process status (d= non-interruptible sleep state, r= run, s= sleep, t= track/Stop, z= zombie process)
X command    name/command line
Y    Wchan   If the process is sleeping, the system function name in sleep is displayed
Z    flags   task flag, reference sched.h

By default, only the more important PID, USER, PR, NI, VIRT, RES, SHR, S,%cpu,%MEM, time+, and COMMAND columns are displayed. You can change the display by using the following shortcut keys.

Change the display by using the F key to select what to display. Press the F key to display a list of columns, press A-Z to show or hide the corresponding column, and then press ENTER to confirm.
Press the o key to change the order in which the columns are displayed. A-Z in the lower case moves the corresponding column to the right, while the uppercase A-Z moves the corresponding column to the left. Finally, press ENTER to confirm.
Press the uppercase F or O key, and then press A-Z to sort the process by the appropriate column. The uppercase R Key can reverse the current sort.

command to use

Top Use Format

Top [-] [d] [P] [Q] [C] [C] [s] [s] [n]

Parameter description

Other useful commands
The following are some of the interactive commands that you can use during the execution of the top command. From a point of view of use, mastering these commands is more important than mastering the options. These commands are single-letter, and if you use the S option in command-line options, some of these commands may be masked out.

K       














W writes the current settings to the ~/.TOPRC file. This is the recommended way to write top configuration files.

Common operations:

Top   // 5-second explicit resource usage for all processes
2  // every 2 seconds explicit resource usage for all processes
The resource usage of the explicit process every 5 seconds and displays the process's command-line arguments (by default, only the process name)
6789// every 5 seconds the PID is 12345 and the PID is 6789 of the resource usage of two processes
every 2 seconds, the PID is 12345 of the resource usage of the process, and the command-line arguments that the process starts are explicitly

Linux system: View system Run status, command W