What is active memory and inactive memory [closed]

Question

What is active memory and inactive memory? I am executing the command vmstat -a on a Linux machine and I am getting the following output:

vmstat -a
procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu------
 r  b   swpd   free  inact active   si   so    bi    bo   in   cs us sy id wa st
 1  0 249900 4801880 2649428 8246152    0    0    42    31    0    0  4  0 95  0  0

But I am not getting what exactly active and inactive memory is... Could you please elaborate?

Answer 1

There are two states of "used" memory, "inactive" and "active".

Active memory is memory that is being used by a particular process.
Inactive memory is memory that was allocated to a process that is no longer running. are pages which have not been accessed "recently"

to see the memory use /proc/meminfo rather than vmstat -a

cat /proc/meminfo  

you need not to clear this Inactive memory When system reboots this memory automatically became vanish, still If you have a large amount of inactive memory ,you can use following command.

free && sync && echo 3 > /proc/sys/vm/drop_caches && echo "" && free

Edit As per @kubanczyk comment: you can find more information from this question