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TOP

command to help understanding system performance.

Block on Top

| Cpu(s) Row
wa = waiting for IO
us = userspace
sy = system/kernel
ni = nice processs
id = idle
hi = hardware interrupts
si = software interrupts
st = steal time (time in involuntary wait by virtual cpu while hypervisor is servicing another processor)

Columns

Listed below are top's available fields. They are always associated with the letter shown,
regardless of the position you may have established for them with the 'o' (Order fields) interactive command.

Any field is selectable as the sort field, and you control whether they are sorted high-to-low or low-to-high.
For additional information on sort provisions see topic 3c. TASK Area Commands.

| Fields
a: PID -- Process Id
    The task's unique process ID, which periodically wraps, though never restarting at zero. 
b: PPID -- Parent Process Pid
    The process ID of a task's parent. 
c: RUSER -- Real User Name
    The real user name of the task's owner. 
d: UID -- User Id
    The effective user ID of the task's owner. 
e: USER -- User Name
    The effective user name of the task's owner. 
f: GROUP -- Group Name
    The effective group name of the task's owner. 
g: TTY -- Controlling Tty
    The name of the controlling terminal. This is usually the device (serial port, pty, etc.) 
    from which the process was started, and which it uses for input or output. 
    However, a task need not be associated with a terminal, in which case you'll see '?' displayed. 
h: PR -- Priority
    The priority of the task. 
i: NI -- Nice value
    The nice value of the task. A negative nice value means higher priority, 
    whereas a positive nice value means lower priority. 
    Zero in this field simply means priority will not be adjusted in determining a task's dispatchability. 
j: P -- Last used CPU (SMP)
    A number representing the last used processor. 
    In a true SMP environment this will likely change frequently since the kernel intentionally uses weak affinity. 
    Also, the very act of running top may break this weak affinity and cause more processes to change 
    CPUs more often (because of the extra demand for cpu time). 
k: %CPU -- CPU usage
    The task's share of the elapsed CPU time since the last screen update, 
    expressed as a percentage of total CPU time. In a true SMP environment, 
    if 'Irix mode' is Off, top will operate in 'Solaris mode' where a task's cpu usage will be divided by the total number of CPUs. 
    You toggle 'Irix/Solaris' modes with the 'I' interactive command. 
l: TIME -- CPU Time
    Total CPU time the task has used since it started. When 'Cumulative mode' is On, 
    each process is listed with the cpu time that it and its dead children has used. 
    You toggle 'Cumulative mode' with 'S', which is a command-line option and an interactive command. 
    See the 'S' interactive command for additional information regarding this mode. 
m: TIME+ -- CPU Time, hundredths
    The same as 'TIME', but reflecting more granularity through hundredths of a second. 
n: %MEM -- Memory usage (RES)
    A task's currently used share of available physical memory. 
o: VIRT -- Virtual Image (kb)
    The total amount of virtual memory used by the task. 
    It includes all code, data and shared libraries plus pages that have been swapped out. 
    (Note: you can define the STATSIZE=1 environment variable and the VIRT will be calculated from the /proc/#/state VmSize field.)
 
    VIRT = SWAP + RES. 
p: SWAP -- Swapped size (kb)
    The swapped out portion of a task's total virtual memory image. 
q: RES -- Resident size (kb)
    The non-swapped physical memory a task has used.
 
    RES = CODE + DATA. 
r: CODE -- Code size (kb)
    The amount of physical memory devoted to executable code, also known as the 'text resident set' size or TRS. 
s: DATA -- Data+Stack size (kb)
    The amount of physical memory devoted to other than executable code, also known as the 'data resident set' size or DRS. 
t: SHR -- Shared Mem size (kb)
    The amount of shared memory used by a task. It simply reflects memory that could be potentially shared with other processes. 
u: nFLT -- Page Fault count
    The number of major page faults that have occurred for a task. 
    A page fault occurs when a process attempts to read from or write to a virtual page that is not currently present in its address space. 
    A major page fault is when disk access is involved in making that page available. 
v: nDRT -- Dirty Pages count
    The number of pages that have been modified since they were last written to disk. 
    Dirty pages must be written to disk before the corresponding physical memory location can be used for some other virtual page. 
w: S -- Process Status
    The status of the task which can be one of: 'D' = uninterruptible sleep 'R' = running 'S' = sleeping 'T' = traced or stopped 'Z' = zombie
    Tasks shown as running should be more properly thought of as 'ready to run' -- their task_struct is simply represented on the Linux run-queue. 
    Even without a true SMP machine, you may see numerous tasks in this state depending on top's delay interval and nice value. 
x: Command -- Command line or Program name
    Display the command line used to start a task or the name of the associated program. 
    You toggle between command line and name with 'c', which is both a command-line option and an interactive command.
 
    When you've chosen to display command lines, 
    processes without a command line (like kernel threads) will be shown with only the program name in parentheses, 
    as in this example: ( mdrecoveryd )
 
    Either form of display is subject to potential truncation if it's too long to fit in this field's current width. 
    That width depends upon other fields selected, their order and the current screen width.
 
    Note: The 'Command' field/column is unique, in that it is not fixed-width. 
    When displayed, this column will be allocated all remaining screen width 
    (up to the maximum 512 characters) to provide for the potential growth of program names into command lines. 
y: WCHAN -- Sleeping in Function
    Depending on the availability of the kernel link map ('System.map'), 
    this field will show the name or the address of the kernel function in which the task is currently sleeping. 
    Running tasks will display a dash ('-') in this column.
 
    Note: By displaying this field, top's own working set will be increased by over 700Kb. 
    Your only means of reducing that overhead will be to stop and restart top. 
z: Flags -- Task Flags
    This column represents the task's current scheduling flags which are expressed in hexadecimal notation and with zeros suppressed. 
    These flags are officially documented in <linux/sched.h>. 
    Less formal documentation can also be found on the 'Fields select' and 'Order fields' screens. 

.toprc

.toprc is the file you do not need to play with it all the time.
Here is my .toprc file.

| ~/.toprc
RCfile for "top with windows"           # shameless braggin'
Id:a, Mode_altscr=0, Mode_irixps=1, Delay_time=3.000, Curwin=0
Def     fieldscur=OQNTKPMehaiWbcdfgJlrsuvyzX
        winflags=130489, sortindx=13, maxtasks=0
        summclr=6, msgsclr=1, headclr=3, taskclr=2
Job     fieldscur=ABcefgjlrstuvyzMKNHIWOPQDX
        winflags=64825, sortindx=0, maxtasks=0
        summclr=6, msgsclr=6, headclr=7, taskclr=6
Mem     fieldscur=ANOPQRSTUVbcdefgjlmyzWHIKX
        winflags=64825, sortindx=13, maxtasks=0
        summclr=5, msgsclr=5, headclr=4, taskclr=5
Usr     fieldscur=ABDECGfhijlopqrstuvyzMKNWX
        winflags=64825, sortindx=4, maxtasks=0
        summclr=3, msgsclr=3, headclr=2, taskclr=3

Playing with color is not advised from interface as it was hard for me :) still you can try using “Z”
Here is how i played.

Select target as upper case letter:
   S = Summary Data,  M = Messages/Prompts,
   H = Column Heads,  T = Task Information
Select color as number:
   0 = black,  1 = red,      2 = green,  3 = yellow,
   4 = blue,   5 = magenta,  6 = cyan,   7 = white
 

Curwin=0 Which define which block you are using start the first one as “0”.

summclr=6, msgsclr=1, headclr=3, taskclr=2 this is the value you can play with with above list of colors.

top.txt · Last modified: 2012/04/12 15:42 by k2patel