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

Views Read Edit View history. If no such location exists, the system allocates a new slab from contiguous physical pages and assigns it to a cache.

Slab allocation was bonwici introduced in the Solaris 2. 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 allocation takes place quickly, because the system builds the objects in advance and readily allocates them from a slab. The next call to allocato memory of the same size will return the now unused memory slot.

Instead of using bufctls, we use the buffers themselves to retain the free list links. With slab allocation, memory chunks suitable to fit data objects of certain type or size are preallocated. Retrieved from ” https: The notion of object caching was therefore introduced in order to avoid the invocation of functions used to initialize object state.


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. This number depends on the size of the associated slabs.

Slab allocation

This allocator is based on a set of object-caching primitives that reduce the cost of allocating complex objects by retaining allocstor state between uses. 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. 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 allows the small slab’s bufctl to be bypassed. When a program sets up a cache, it allocates a number of objects to the slabs associated with that cache.

It represents one memory allocation to the cache from the machine, and whose size is customarily a multiple of the page size.

Slab Allocator | Oracle Jeff Bonwick’s Blog

The discussion page may contain suggestions. This article may need to be rewritten entirely to comply with Wikipedia’s quality standards.

This page was last edited on 23 Decemberat The last part of the page contains the ‘slab header’, which is the information needed to retain the slab. It is analogous to an object poolbut only applies heff memory, not other resources.

However, in many xllocator the cost of initializing and destroying the object exceeds the cost of allocating and freeing mem Abstract This paper presents a comprehensive bonwickk overview of the SunOS 5. This paper presents a comprehensive design overview of the SunOS 5. Not to be confused with Slab unit. Advanced Search Include Citations.


Retrieved 28 December From Wikipedia, the free encyclopedia. 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. Destruction of the object does not free up the memory, but only bomwick a slot which is put in the list of free slots by the slab allocator.

A slab is the amount by which a cache can grow or shrink.

Slah primary motivation allocstor slab allocation is that the initialization and destruction of kernel data objects can actually outweigh the cost of allocating memory for them. 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. 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.

Retrieved 18 November Initially, the system marks each slab as “empty”.