The slab allocator: an object-caching kernel memory allocator . Jeff Bonwick, Jonathan Adams, Magazines and Vmem: Extending the Slab. Implementation of the Slab Allocator as described in “The Slab Allocator: An Object-Caching Kernel Memory Allocator” by Jeff Bonwick. – lucastsa/ slab_allocator. This package provides a simple implementation of a Slab memory allocator (Jeff Bonwick: “The Slab Allocator: An Object-Caching Kernel Memory Allocator”).

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Slab Allocator

This page was last edited on 23 Decemberat Initially, the system marks each slab as “empty”. Advanced Search Include Citations. A fast kernel memory allocator is therefore essential. In this context, a slab is one or more contiguous pages in the memory containing pre-allocated memory chunks. By using this site, you agree to the Terms of Use and Privacy Policy. Instead jsff using bufctls, we use the buffers themselves to retain the free list links.

These small slabs need aloocator be optimized further from the logical layout, by avoiding using bufctls which would be just as large as the data itself and cause memory usage to be much greater. When a program sets up a cache, it allocates a number of objects to the slabs associated with that cache.

The new object gets allocated from this slab, and its location becomes marked as “partial”. Not to be confused with Slab unit.

A slab is the amount by which a cache can grow or shrink. A small slab is exactly one page, and has a defined structure that allows bufctls to be avoided.


Advanced Search Include Citations Disambiguate. It eliminates fragmentation caused by allocations and deallocations. This allows the small slab’s bufctl to be bypassed.

Slab Allocator | Oracle Jeff Bonwick’s Blog

Slab allocation is a memory management mechanism intended for the efficient memory allocation of kernel objects. The last part of the jff contains the ‘slab header’, which is the information needed to retain the slab. It is analogous to an object jdffbut only applies to memory, not other resources. If no such location exists, the system allocates a new slab from contiguous physical pages and assigns it to a cache. The allocation takes place quickly, because the system builds the objects in advance and readily allocates them from a slab.

This article may need to be rewritten entirely to comply with Wikipedia’s quality standards.

Introduction The allocation and freeing of objects are among the most common operations in the kernel. Webarchive template wayback links Use dmy dates from August Wikipedia articles needing rewrite from May All articles needing rewrite Jrff articles with unsourced statements Articles with unsourced statements from April Retrieved 18 November The next call to allocate memory of the same size will return the now unused memory slot.

CiteSeerX — The Slab Allocator: An Object-Caching Kernel Memory Allocator

The reason for the large slabs having a different layout from the small slabs is that it allows large slabs to pack better into page-size units, which helps with fragmentation.


Retrieved from ” https: This process eliminates the need to search for suitable memory space and greatly alleviates memory fragmentation. The discussion page may contain suggestions. Destruction of the object does not free up the slah, but only opens a slot which is put in the list of free slots by the slab allocator.

Slab allocation

Abstract This paper presents a comprehensive design overview of the SunOS 5. With slab allocation, memory chunks suitable to fit data objects of certain type or size are preallocated.

This number depends on the size of the associated slabs. However, in many cases the cost of initializing and destroying the object exceeds the cost of bonwifk and freeing mem The technique is used to retain allocated memory that contains a data object of a certain type for reuse upon subsequent allocations of objects of the same type.

The slab contains a list of bufctls, which are simply controllers for each buffer that can be allocated a buffer is the memory that the user of a slab allocator would use.

From Wikipedia, the free encyclopedia. Views Read Edit View history. When the process calls for a new kernel object, the system tries to find a free location for that object on a partial slab in a cache for that type of object.