free: The amount of idle (unused) memory.

swpd: The amount of virtual memory used, i.e., how much memory has been swapped out.

Any queued interrupts for that process are handled when the process resumes its usual activity. Typically, this process is a device driver waiting for some resource to be free. They can’t be interrupted until they complete their current action. These aren’t sleeping, but performing a blocking system call.

b: The number of processes in uninterruptible sleep.

They’re either running or waiting for their next time-sliced burst of CPU cycles.

r: The number of “runnable” processes.

There are a lot of data points in that report, so we’ll break them down: This is the output without the wrap-around: procs -memory-swap-io-system-cpu. It gives you a report on a variety of swap-related statistics based on the average values since the last reboot. You can use the vmstat command to take a deeper dive into how your swap space (or virtual memory) is being used. RAM and swap space work closely together.

It’s impossible to have a good understanding of the way RAM is used in your Linux box without an appreciation of the state of your swap space. RELATED: How to Use the free Command on Linux The vmstat Command

You can also use the following nifty trick we tweaked from one of our readers to see the percentage of swap space that is used: free -m | grep Swap | awk '' Free: The amount of remaining (unused) swap space.Used: The amount of swap space that’s in use.Total: The size of the swap partition or file.The Swap columns contain the following information: Available: This is an estimate of the memory that’s available to service memory requests from applications and any other operational software on your computer.This can be released quickly by the kernel if required. Buff/cache: Amount of memory used for buffers and cache.Shared: Amount of memory used by the tmpfs file systems.Used: The sum of Free+Buffers+Cache subtracted from the total amount.Total: The total amount of physical RAM on this computer.The Mem columns contain the following information: This is the output we get: total used free shared buff/cache available

Linux check process memory usage