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Allocators

From dankwiki

As of 2023, Glibc uses ptmalloc2 aka Doug Lea's malloc with arena modifications by Wolfram Gloger. It's critical to know that allocations equal to or larger than MMAP_THRESHOLD (by default 128KiB) will be serviced by anonymous mmap.

Multiprocessing-suitable dropins

  • Hoard - Emery Berger's multiprocessor-geared allocator, a drop-in malloc(3) replacement
  • TCMalloc - Google's "Thread-Caching malloc", another malloc(3) drop-in for multiprocessing
  • rpmalloc the Rampant Pixel Mallocator, lock-free, 16-byte aligned

Realtime-suitable dropins

Arena

Slab

Linux kernel variants

The following data is collected from kernel 2.6.30:

  • SLAB: The original. From the Kconfig help:
The regular slab allocator that is established and known to work
well in all environments. It organizes cache hot objects in
per cpu and per node queues.
  • SLUB (Christoph Lameter, 2007) reduced the size of the slab object queue and improved scalability for many processors (LKML). From the Kconfig help:
SLUB is a slab allocator that minimizes cache line usage
instead of managing queues of cached objects (SLAB approach).
Per cpu caching is realized using slabs of objects instead
of queues of objects. SLUB can use memory efficiently
and has enhanced diagnostics. SLUB is the default choice for
a slab allocator.

References