In
operating system
An operating system (OS) is system software that manages computer hardware and software resources, and provides common daemon (computing), services for computer programs.
Time-sharing operating systems scheduler (computing), schedule tasks for ...
s, write barrier is a mechanism for enforcing a particular ordering in a sequence of writes to a storage system in a computer system. For example, a write barrier in a
file system is a mechanism (program logic) that ensures that in-memory file system state is written out to persistent storage in the correct order.
In garbage collection
A write barrier in a
garbage collector is a fragment of code emitted by the compiler immediately before every store operation to ensure that (e.g.) generational invariants are maintained.
In computer storage
A write barrier in a
memory system, also known as a
memory barrier
In computing, a memory barrier, also known as a membar, memory fence or fence instruction, is a type of barrier instruction that causes a central processing unit (CPU) or compiler to enforce an ordering constraint on memory operations issued ...
, is a hardware-specific
compiler intrinsic
In computer software, in compiler theory, an intrinsic function, also called built-in function or builtin function, is a function (subroutine) available for use in a given programming language whose implementation is handled specially by the comp ...
that ensures that all preceding memory operations
"happen before" all subsequent ones.
See also
*
Native Command Queuing
In computing, Native Command Queuing (NCQ) is an extension of the Serial ATA protocol allowing hard disk drives to internally optimize the order in which received read and write commands are executed. This can reduce the amount of unnecessary driv ...
References
External links
Barriers and journaling filesystems(LWN.net, May 21, 2008)
Compilers
Memory management
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