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Take care my Linux Memory Usage Summary in console – CentOS

I recently saw my AWS EC2 instance’s states at SSH helper program (Not a putty program).

I saw below.

[centos@ip-172-31-xx-xx ~]$ free -h
             total       used       free     shared    buffers     cached
Mem:          1.8G       1.0G       869M       144K       137M       267M
-/+ buffers/cache:       600M       1.2G
Swap:           0B         0B         0B

I understand buffers and cached usage are reserved usage, so it is empty usage. But, I didn’t understand this.

-/+ buffers/cache: 600M 1.2G

What does it mean?

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2

Answers


  1. 0

    According to the post Meaning of the buffers/cache line in the output of free.

    It seems to be the used memory minus the free memory in cache and buffers and the free memory plus the free memory in cache and buffers.

    You can calculate the value if you form the sum of buffers and cached (400M) and substract the value from used (1000M – 400M = 600M) and add it on free (869M + 400~ 1,2G).

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  2. 0

    As an alternative look at the contents of: /proc/meminfo

    For example:

    grep MemAvailable /proc/meminfo

    and:

    cat /proc/meminfo

    Notice that MemAvailable is only available in modern Linux kernels (not RHEL/CentOS 6 unless you run it with a newer kernel, Like Oracle Unbreakable Linux does)

    For fun and education look also at: https://www.linuxatemyram.com/

    For a more convenient info on your systems resource usage you may be interested in something like atop: https://haydenjames.io/use-atop-linux-server-performance-analysis/ or one of the other top tools like these: https://haydenjames.io/alternatives-top-htop/

    I’m just no big fan of free so I avoid it like the plague 😉

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