To see these two columns instead of the buff and cache columns, include the -a option, as shown: vmstat 5 -a -S M As they would suggest, these show the amount of inactive and active memory. If you use the -a (active) option the buff and cache memory columns are replaced by the “inact” and “active” columns. Note that the -S option does not affect the IO block statistics. The memory and swap statistics are now shown in megabytes. If you do not provide a count value, vmstat will run until it is stopped by Ctrl+C. The count value tells vmstat how many updates to perform before it exits and returns you to the command prompt. If you need to have rapid updates to try to diagnose a problem, it is recommended that you use a count value as well as a delay value. Using too low a delay value will put additional strain on your system. To have the statistics updated every five seconds, we’d use the following command: vmstat 5Įvery five seconds vmstat will add another line of data to the table. We can have vmstat provide regular updates to these figures by using a delay value. This is the time a virtual machine has to wait for the hypervisor to finish servicing other virtual machines before it can come back and attend to this virtual machine. st: Time stolen from a virtual machine. wa: Time spent waiting for input or output.That is, how much time is spent in user time processing and in nice time processing. us: Time spent running non-kernel code.These values are all percentages of the total CPU time. A context switch is when the kernel swaps from system mode processing into user mode processing. cs: The number of context switches per second.in: The number of interrupts per second, including the clock.bo: Blocks sent to a block device. The number of data blocks used to swap virtual memory out of RAM and into swap space.The number of data blocks used to swap virtual memory back into RAM. bi: Blocks received from a block device.so: Amount of virtual memory swapped out to swap space.si: Amount of virtual memory swapped in from swap space.cache: the amount of memory used as cache.buff: the amount of memory used as buffers.free: the amount of idle (currently unused) memory.In other words, how much memory has been swapped out., swpd: the amount of virtual memory used.Typically the process is a device driver waiting for some resource to come free. Any queued interrupts for that process are handled when the process resumes its usual activity. The process isn’t sleeping, it is performing a blocking system call, and it cannot be interrupted until it has completed its current action.
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