Linux: Slab Defragmentation

“‘Slab defragmentation is mainly an issue if Linux is used as a
fileserver and large amounts of dentries, inodes and buffer heads
accumulate,’ Christoph Lameter explained when posting the fifth
version of his patchset. He continued, ‘in some load situations the
slabs become very sparsely populated so that a lot of memory is
wasted by slabs that only contain one or a few objects. In extreme
cases the performance of a machine will become sluggish since we
are continually running reclaim. Slab defragmentation adds the
capability to recover wasted memory.’ Christoph noted that the
patch is difficult to validate and measure because, ‘activities are
only performed when special load situations are
encountered…'”

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