Commit fc1ca3d5 authored by Yang Shi's avatar Yang Shi Committed by Jonathan Corbet
Browse files

doc: add description to dirtytime_expire_seconds 



commit 1efff914 ("fs: add
dirtytime_expire_seconds sysctl") introduced dirtytime_expire_seconds
knob, but there is not description about it in
Documentation/sysctl/vm.txt.

Add the description for it.

Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: default avatarYang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: default avatarJonathan Corbet <corbet@lwn.net>
parent 83d4fcb3

Documentation/sysctl/vm.txt

+13 −0
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ Currently, these files are in /proc/sys/vm: 
- dirty_bytes

- dirty_expire_centisecs

- dirty_ratio

- dirtytime_expire_seconds

- dirty_writeback_centisecs

- drop_caches

- extfrag_threshold
@@ -178,6 +179,18 @@ The total available memory is not equal to total system memory. 


==============================================================



dirtytime_expire_seconds



When a lazytime inode is constantly having its pages dirtied, the inode with

an updated timestamp will never get chance to be written out.  And, if the

only thing that has happened on the file system is a dirtytime inode caused

by an atime update, a worker will be scheduled to make sure that inode

eventually gets pushed out to disk.  This tunable is used to define when dirty

inode is old enough to be eligible for writeback by the kernel flusher threads.

And, it is also used as the interval to wakeup dirtytime_writeback thread.



==============================================================



dirty_writeback_centisecs



The kernel flusher threads will periodically wake up and write `old' data