Contents
What is RB in vmstat?
Meaning of the individual Values. (Source man vmstat): Procs r: The number of processes waiting for run time. b: The number of processes in uninterruptible sleep. Memory swpd: the amount of virtual memory used.
What does vmstat mean in Linux?
Virtual memory statistics reporter
Virtual memory statistics reporter, also known as vmstat , is a Linux command-line tool that reports various bits of system information. Things like memory, paging, processes, IO, CPU, and disk scheduling are all included in the array of information provided. Subsequent reports use measurements of delay and count.
What is WA in vmstat?
The vmstat wa column is the percentage of time that the CPU was idle with pending local disk I/O and NFS-mounted disks. If there is at least one outstanding I/O to a disk when wait is running, the time is classified as waiting for I/O.
How do I run vmstat?
How to Use vmstat
- If you don’t have vmstat on your machine, install it by running:
- Enter your password and wait for the installation to finish.
- Run vmstat without parameters to display a system report with average statistics since the last boot.
- For additional reports, use vmstat options, delay, and count.
What is uninterruptible sleep Linux?
An Uninterruptible sleep state is one that won’t handle a signal right away. It will wake only as a result of a waited-upon resource becoming available or after a time-out occurs during that wait (if the time-out is specified when the process is put to sleep).
What is the use of vmstat in Linux and troubleshooting?
The vmstat (virtual memory statistics) command allows you to monitor your system’s memory usage. It shows how much virtual memory there is, and how much is free and paging activity. You can observe page-ins and page-outs as they happen.
What is vmstat command used for?
vmstat command in Linux/Unix is a performance monitoring command of the system as it gives the information about processes, memory, paging, block IO, disk, and CPU scheduling. All these functionalities makes the command vmstat also known as virtual memory statistic reporter.
What vmstat command does?
The vmstat command reports statistics about kernel threads in the run and wait queue, memory, paging, disks, interrupts, system calls, context switches, and CPU activity. The reported CPU activity is a percentage breakdown of user mode, system mode, idle time, and waits for disk I/O.
In which vmstat command is available?
Why we use vmstat in Linux?
How can I stop uninterruptible sleep?
As the name implies, they are uninterruptible. You can only clear them by rebooting the server or waiting for the I/O to respond. It is normal to see processes in a “D” state when the server performs I/O intensive operations. If performance becomes an issue, you may need to check the health of your disks.
What is an uninterruptible process?
An uninterruptible process is a process which happens to be in a system call (kernel function) that cannot be interrupted by a signal. To understand what that means, you need to understand the concept of an interruptible system call.
What do you need to know about vmstat?
vmstat (virtual memory statistics) is a valuable monitoring utility, which also provides information about block IO and CPU activity in addition to memory.
Is the runqueue greater than B in vmstat?
If R (runqueue) is greater than B (waitqueue) in vmstat, is it I/O bound? If the runqueue is the number of processes waiting for their turn on the CPU + processes currently running, and waitqueue is the number of processes waiting for I/O, then wouldn’t B in the vmstat output being greater than R mean that there is an I/O bound, not CPU bound?
What is virtual memory statistics reporter in Linux?
Virtual memory statistics reporter, also known as vmstat, is a Linux command-line tool that reports various bits of system information. Things like memory, paging, processes, IO, CPU, and disk scheduling are all included in the array of information provided.
What does Io bi and Bo mean in vmstat?
IO bi: Blocks received from a block device (blocks/s). bo: Blocks sent to a block device (blocks/s). System in: The number of interrupts per second, including the clock. cs: The number of context switches per second.