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--- proc:buddy_info_file [2017/04/06 11:21] – removed peter
+++ proc:buddy_info_file [2020/07/15 09:30] (current) – external edit 127.0.0.1
@@ Line 1: / Line 1: @@
+====== Proc - Buddy Info file ======
+External fragmentation is a problem under some workloads, and buddyinfo is a useful tool for helping diagnose these problems.  Buddyinfo will give you a clue as to how big an area you can safely allocate, or why a previous allocation failed.
+<code bash>
+cat /proc/buddyinfo
+Node 0, zone      DMA      0      4      5      4      4      3 ...
+Node 0, zone   Normal      1      0      0      1    101      8 ...
+Node 0, zone  HighMem      2      0      0      1      1      0 ...
+</code>
+Each column represents the number of pages of a certain order which are available.  In this case, there are 0 chunks of 2^0*PAGE_SIZE available in ZONE_DMA, 4 chunks of 2^1*PAGE_SIZE in ZONE_DMA, 101 chunks of 2^4*PAGE_SIZE available in ZONE_NORMAL, etc...
+More information relevant to external fragmentation can be found in [[Proc:Page Type Info file|pagetypeinfo]].