free mem output

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craig91
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Joined: 2015/09/29 21:55:37

free mem output

Post by craig91 » 2015/09/29 21:58:14

I switched from RHEL7 to CENTOS7 yesterday and have noticed the free command outputs information different. The "buffers/cache:" line is not present, is there any particular reason?

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[root@centOS7 ~]# free -m
              total        used        free      shared  buff/cache   available
Mem:           1999         872         339          80         787         831
Swap:          2047         339        1708
versus something like this

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[root@itsprite /]# free 
             total       used       free     shared    buffers     cached
Mem:       1010860     934976      75884       8280          0     107944
-/+ buffers/cache:     827032     183828
Swap:      2129916     138000    1991916

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TrevorH
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Re: free mem output

Post by TrevorH » 2015/09/29 22:23:53

Post the output from uname -a on both systems.
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craig91
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Joined: 2015/09/29 21:55:37

Re: free mem output

Post by craig91 » 2015/09/29 23:15:58

TrevorH wrote:Post the output from uname -a on both systems.
The other one was just one I found online as I knew that was how it looked when I had RHEL7.

Here's the output for the CentOS7 machine.

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[root@centOS7 ~]# uname -a
Linux centOS7 3.10.0-229.el7.x86_64 #1 SMP Fri Mar 6 11:36:42 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux

MartinR
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Location: UK

Re: free mem output

Post by MartinR » 2015/09/30 09:15:35

On a CentOS 6 system free is version 3.2.8 and has a man page dating from 1993. Under CentOS 7.1 it is version 3.3.10 with a man page dating from July last year. Your CentOS 7 code is the new form, the second code is the old form. The "available" field is the replacement for the old "free:+/- buffers" entry. The newer form claims a more sophisticated view of the buffers, cache and page tables (what can geuinely be released and what can't) rather than the old simplistic arithmetic form.

craig91
Posts: 7
Joined: 2015/09/29 21:55:37

Re: free mem output

Post by craig91 » 2015/09/30 13:29:00

MartinR wrote:On a CentOS 6 system free is version 3.2.8 and has a man page dating from 1993. Under CentOS 7.1 it is version 3.3.10 with a man page dating from July last year. Your CentOS 7 code is the new form, the second code is the old form. The "available" field is the replacement for the old "free:+/- buffers" entry. The newer form claims a more sophisticated view of the buffers, cache and page tables (what can geuinely be released and what can't) rather than the old simplistic arithmetic form.
Thank you MartinR, makes sense!

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