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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The notion of object caching was therefore introduced in order to avoid the invocation of functions used to initialize object state. It eliminates fragmentation caused by allocations and deallocations. It represents one memory allocation to the cache from the machine, and whose size is customarily a multiple of the page size.

Instead of using bufctls, we use the buffers themselves to retain the free list links.

The discussion page may contain suggestions. These small slabs need to 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. This paper presents a comprehensive design overview of the SunOS 5.

Abstract This paper presents a comprehensive design overview of the SunOS 5. This article may need to be rewritten entirely to comply with Wikipedia’s quality standards.

A slab must contain a list of free buffers or bufctlsas well as a list of the bufctls that have been allocated in the case of a large slab size. Retrieved 18 November 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. Destruction of the object does not free up the memory, but only opens a slot which is put in the list of free slots by the slab allocator. The allocator’s object caches respond dynamically to global memory pressure, and employ an objectcoloring scheme that improves the system’s overall cache utilization and bus balance.


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Slab allocation

Slab allocation is a memory management mechanism intended for the efficient memory allocation of kernel objects. Advanced Search Include Citations Disambiguate.

A slab is the amount by which a cache can grow or shrink. This page was last edited on 23 Decemberat This number depends on the size of the associated slabs. From Wikipedia, the free encyclopedia. These same primitives prove equally effective for managing stateless memory e. This process eliminates the need to search for suitable memory space and greatly alleviates memory fragmentation.

Introduction The allocation and freeing of objects are among the most common operations in the kernel. 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. This allows the small slab’s bufctl to be bypassed. Starting at the first address of that page, there are as many buffers as can be allocated without running into the slab header at the end of the page.

Slab allocation was first introduced in the Solaris 2. It is analogous to an object poolbut only applies to memory, not other resources. The next call to allocate memory of the same size will return the now unused memory slot. 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.


When a program sets up a cache, it allocates a number of objects to the slabs associated with that cache.

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

Webarchive template wayback links Use allocatpr dates from August Wikipedia articles needing rewrite from May All articles needing rewrite All articles with unsourced statements Articles with unsourced statements from April This allocator is based on a set of object-caching primitives that reduce the cost of allocating complex objects by retaining their state between uses.

Retrieved from ” https: The new object gets allocated from this slab, and its location becomes marked as “partial”. Views Read Edit View history.

Retrieved 28 December Initially, the system marks each slab as “empty”.

By using this site, you agree to the Terms of Use and Privacy Policy. The primary motivation for slab allocation is that the initialization and destruction of kernel data objects can actually outweigh the cost of allocating memory for them.

Not to be confused with Slab unit. However, in many cases the cost of initializing and destroying the object exceeds the cost of allocating and freeing mem