Readahead is a system call of the Linux kernel that loads a file's contents into the page cache. This prefetches the file so that when it is subsequently accessed, its contents are read from the main memory (RAM) rather than from a hard disk drive (HDD), resulting in much lower file access latencies.[1][2]
Many Linux distributions 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 boot parameter, it will record all file accesses during bootup and write a new list of files to be read during later boot sequences. This will make additional installed services start faster, because they are not included in the default readahead list.[3]
In Linux distributions that use systemd, readahead binary (as part of the boot sequence) was replaced by systemd-readahead.[4][5] However, support for readahead was removed from systemd in its version 217, being described as unmaintained and unable to provide expected performance benefits.[6]
Certain experimental page-level prefetching systems have been developed to further improve performance.[7]
| |||||||||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Organization |
| ||||||||||||||||||||||||||
Technical |
| ||||||||||||||||||||||||||
Adoption |
| ||||||||||||||||||||||||||
|
| |
---|---|
Linux kernel |
|
Controversies |
|
Distributions |
|
Organizations |
|
Adoption |
|
Media |
|
Professional related certifications |
|
|
![]() | This Linux-related article is a stub. You can help Wikipedia by expanding it. |