Monitoring the Virtual Memory Statistics

This command (umstat)is used to monitor virtual memory statistics.

Practice

The given example shows the usage of the vmstat commands.

# vmstat

procs                memory           swap                io         system            cpu

r    b   w    swpd      free   si   so   bi   bo         in         cs   us  sy         id

0   0    0     680      1544    1   1    35 96          418      27   1   4          96

In the given example, under procs there are 3 fields. That is the number of processes waiting for run time (r), the number of processes in uninterruptable sleep(b) and the number of processes swapped out but otherwise runnable (w), the memory field reports on usage of real and virtual memory. Given fields there are 3 fields: The amount of virtual memory used in kB (swpd), the amount of idle memory in kB (free) and the amount of memory used as buffers in kB (buff). Under system there are 2 fields: The number of interrupts per second, involving the clock (in), and the number of context switches per second (cs), and these are percentages of user time(us), total CPU time, Under cpu there are 2 fields: system time (sy) and idle time (id).Below Swap we are having 3 fields: Amount of memory swapped in from disk in kB/s (si), amount of memory swapped to disk in kB/s (so) and the blocks sent to a block device in blocks/s (IO), the blocks received from a block device in blocks/s (bo).