Understanding Top Command

Understanding Top Command

1 Row — top

 This first line indicates in order:

• current time (11:37:19)
• uptime of the machine (up 1 day, 1:25)
• users sessions logged in (3 users)
• average load on the system (load average: 0.02, 0.12, 0.07) the 3 values refer to the last minute, five minutes and 15 minutes.

2 Row – task

 The second row gives the following information:

• Processes running in totals (73 total)
• Processes running (2 running)
• Processes sleeping (71 sleeping)
• Processes stopped (0 stopped)
• Processes waiting to be stoppati from the parent process (0 zombie)

3 Row – cpu

 The third line indicates how the cpu is used. If you sum up all the percentages the total will be 100% of the cpu. Let’s see what these values indicate in order:

• Percentage of the CPU for user processes (0.3%us)
• Percentage of the CPU for system processes (0.0%sy)
• Percentage of the CPU processes with priority upgrade nice (0.0%ni)
• Percentage of the CPU not used (99,4%id)
• Percentage of the CPU processes waiting for I/O operations(0.0%wa)
• Percentage of the CPU serving hardware interrupts (0.3% hi — Hardware IRQ
• Percentage of the CPU serving software interrupts (0.0% si — Software Interrupts
• The amount of CPU ‘stolen’ from this virtual machine by the hypervisor for other tasks (such as running another virtual machine) this will be 0 on desktop and server without Virtual machine. (0.0%st — Steal Time)

4 and 5 Rows – memory usage

The fourth and fifth rows respectively indicate the use of physical memory (RAM) and swap. In this order: Total memory in use, free, buffers cached. On this topic you can also read the following article

Following Rows — Processes list

And as last thing ordered by CPU usage (as default) there are the processes currently in use. Let’s see what information we can get in the different columns:

• PID – l’ID of the process(4522)
• USER – The user that is the owner of the process (root)
• PR – priority of the process (15)
• NI – The “NICE” value of the process (0)
• VIRT – virtual memory used by the process (132m)
• RES – physical memory used from the process (14m)
• SHR – shared memory of the process (3204)
• S – indicates the status of the process: S=sleep R=running Z=zombie (S)
• %CPU – This is the percentage of CPU used by this process (0.3)
• %MEM – This is the percentage of RAM used by the process (0.7)
• TIME+ –This is the total time of activity of this process (0:17.75)
• COMMAND – And this is the name of the process (bb_monitor.pl)