Monday, January 25, 2010

System Monitor tabs – Processes

In the Linux world, processes are the programs running on the system. It often helps to know what processes are running on the Ubuntu system, especially because many of them run in background mode. Processes running in background mode don’t appear on your desktop, so you have no way of knowing they’re running. These programs perform most of the behind-the-scenes work, such as monitoring the battery level in your laptop and scheduling programs to run at specific times.

Processes appear in a table format in the window display. The default view shows all processes currently being run by your user account. Alternatively, you can watch all of the processes running on the system, or just the ones that are actively working, by clicking the View menu item from the menu bar and selecting which option you want to view.

Selecting the Dependencies entry in the View menu reorders the process list to show which processes started which other processes. This option produces a drop-down tree, with parent processes at the top level and, below that, any child processes that the parent started. You can roll up the children processes and display only the parent processes by clicking the arrow icon next to the parent process.

You can sort the process rows in the list based on any of the table columns. For example, to see what processes are using the largest percentage of CPU time, click the % CPU column heading. The System Monitor automatically sorts the rows based on percentage of CPU usage. Clicking the column heading a second time reverses the order of the list.

You can customize the table by adding or removing data columns for the processes. Click Edit -> Preferences with the Processes tab selected to see the options available for the
Processes tab.

System Monitor Process Table Columns
Process Name: The program name of the running process

User: The owner of the process

Status: The status (either sleeping or running) of the process

Virtual Memory: The amount of virtual system memory allocated for the process

Resident Memory: The amount of physical memory allocated for the process

Writable Memory: The amount of memory allocated to the process currently loaded into physical memory (active)

Shared Memory: The amount of memory shared between this process and other processes

X-Server Memory: The amount of memory the process shares with the X Windows (GUI) server

% CPU: The percentage of total CPU time the process is using

CPU Time: The actual CPU time the process is using

Started: The time the process started running

Nice: The system priority of the process (higher nice numbers have lower priority
on the system)

ID: The unique process ID (PID) the system assigned to the process

Security Context: The security classification assigned by the SELinux security system

Command Line: The name of the command and any command-line arguments used to start it

Memory: The amount of system memory the process is using

There are also a few other options you can set while you’re in the Properties dialog box of the Processes tab:

• Update Interval in Seconds: Specifies how frequently the System Monitor
refreshes the process table data.

• Enable Smooth Refresh: Gathers new process information before refreshing the process table data, rather than refreshing table data as it gathers process information.

• Alert Before Ending or Killing Processes: Produces a warning that you are about to terminate a running process.

• Solaris Mode: Calculates the percentage of CPU utilization based on the number of active CPU cores. Thus, if two separate processes are maxing out two separate CPU cores, they would both show 50 percent CPU utilization instead of both showing 100 percent.

You can also control processes that you own from the Processes tab. Right-clicking a process produces a menu that allows you to stop, end, or kill a process, along with entries that allow you to change the priority of the process.

The System Monitor allows you to stop only the processes that you own. These are processes that your desktop started when you logged in and any programs or applets that you run from your desktop environment. Unfortunately, it doesn’t tell you that. It’ll allow you to select a process that you don’t own and click the End Process button. However, the attempt to end a process you don’t own will fail.

Source of Information : Wiley Ubuntu Linux Secrets

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