Friday, August 25, 2017

Oracle Linux - inspect memory fragments with buddyinfo

The file /proc/buddyinfo is used primarily for diagnosing memory fragmentation issues. Using the buddy algorithm, each column represents the number of pages of a certain order (a certain size) that are available at any given time. You get to view the free fragments for each available order, for the different zones of each numa node.

The content of /proc/buddinfo as shown below will show you the number of free memory chunks. You have to read the numbers from left to right where the first column each value is 2^(0*PAGE_SIZE) the second is 2^(1*PAGE_SIZE) etc ect.

An example of the content of the buddyfile on Oracle Linux 6 can be seen below:

[root@jenkins proc]# cat buddyinfo 
Node 0, zone      DMA     15     32     84     24      6      5      2      0      0      0      0 
Node 0, zone    DMA32    604    342    165     64     28     10     15      2      1      0      0 
[root@jenkins proc]#
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