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rated 0 times [  8] [ 0]  / answers: 1 / hits: 2176  / 3 Years ago, sun, june 27, 2021, 10:13:59

I'm trying to debug an OOM situation in an Ubuntu 12.04 server, and looking at the Memory graphs in Landscape, I noticed that there wasn't any serious memory usage spike. Then I looked at the output of the free command and I wasn't quite sure how both memory usage results relate to each other.



Here's landscape's output on the server:



$ landscape-sysinfo 

  System load:  0.0               Processes:           93

  Usage of /:   5.6% of 19.48GB   Users logged in:     1

  Memory usage: 26%               IP address for eth0: -

  Swap usage:   2%


Then I ran the free command and I get:



$ free -m

             total       used       free     shared    buffers     cached

Mem:           486        381        105          0          4        165

-/+ buffers/cache:        212        274

Swap:          255          7        248


I can understand the 2% swap usage, but where does the 26% memory usage come from?


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 Answers
1

In Landscape



landscape-sysinfo actually gets its data directly from /proc/meminfo:



dpb@helo:~$ cat /proc/meminfo |egrep 'MemTotal:|Active:'

MemTotal:       12286760 kB

Active:          3794832 kB

dpb@helo:~$


The calculation of "Memory Usage" in this case would be:



((MemTotal - Active) / MemTotal) * 100


You can see these calculations in:



/usr/share/pyshared/landscape/sysinfo/memory.py

/usr/share/pyshared/landscape/lib/sysstats.py


gets its data directly from /proc/meminfo:



In free



The free utility also gets its data directly from /proc/meminfo:



Mem




  • total: MemTotal

  • used: MemTotal - MemFree

  • free: MemFree

  • buffers: Buffers

  • cached: Cached



Buffers/cache




  • used: MemTotal - MemFree - Buffers - Cached

  • free: MemFree + Buffers + Cached



Swap




  • total: SwapTotal

  • used: SwapTotal - SwapFree

  • free: SwapFree



Total




  • total: MemTotal + SwapTotal

  • used: MemTotal - MemFree + SwapTotal - SwapFree

  • free: MemFree + SwapFree



Corrected cached -- lzap


[#33974] Sunday, June 27, 2021, 3 Years  [reply] [flag answer]
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