Readahead
Encyclopedia
readahead is the file prefetching
technology used in the Linux
operating system
. It is a system call
that loads a file's contents into the page cache. When a file is subsequently accessed, its contents are read from physical memory rather than from disk, which is much faster.
Many distributions of Linux use readahead on a list of commonly used files to speed up booting
. In such a setup, if the kernel
is booted with the profile parameter, it will record all file accesses during bootup and write a new list of files to be read before booting. This will make additional installed services start faster, because they are not included in the default readahead list.
Prefetcher
The Prefetcher is a component of versions of Microsoft Windows starting with Windows XP. It is a component of the Memory Manager that speeds up the Windows boot process, and shortens the amount of time it takes to start up programs...
technology used in the Linux
Linux
Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...
operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
. It is a system call
System call
In computing, a system call is how a program requests a service from an operating system's kernel. This may include hardware related services , creating and executing new processes, and communicating with integral kernel services...
that loads a file's contents into the page cache. When a file is subsequently accessed, its contents are read from physical memory rather than from disk, which is much faster.
Many distributions of Linux use readahead on a list of commonly used files to speed up booting
Booting
In computing, booting is a process that begins when a user turns on a computer system and prepares the computer to perform its normal operations. On modern computers, this typically involves loading and starting an operating system. The boot sequence is the initial set of operations that the...
. In such a setup, if the kernel
Kernel (computing)
In computing, the kernel is the main component of most computer operating systems; it is a bridge between applications and the actual data processing done at the hardware level. The kernel's responsibilities include managing the system's resources...
is booted with the profile parameter, it will record all file accesses during bootup and write a new list of files to be read before booting. This will make additional installed services start faster, because they are not included in the default readahead list.