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explain slot counts tied to slab size classes

pull/69/head
Daniel Micay 2018-11-19 00:17:43 -05:00
parent 5b048a28c2
commit a5ed64d01a
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@ -321,6 +321,13 @@ classes for every power of two spacing which results in bounding the internal
fragmentation below 20% for each size class. This also means there are 4 size fragmentation below 20% for each size class. This also means there are 4 size
classes for each doubling in size. classes for each doubling in size.
The slot counts tied to the size classes are specific to this allocator rather
than being taken from jemalloc. Slabs are always a span of pages so the slot
count needs to be tuned to minimize waste due to rounding to the page size. For
now, this allocator is set up only for 4096 byte pages as a small page size is
desirable for finer-grained memory protection and randomization. It could be
ported to larger page sizes in the future.
| size class | worst case internal fragmentation | slab slots | slab size | internal fragmentation for slabs | | size class | worst case internal fragmentation | slab slots | slab size | internal fragmentation for slabs |
| - | - | - | - | - | | - | - | - | - | - |
| 16 | 93.75% | 256 | 4096 | 0.0% | | 16 | 93.75% | 256 | 4096 | 0.0% |