Linux-ext4 Archive on
 help / color / Atom feed
* Query about ext4 commit interval vs dirty_expire_centisecs
@ 2019-11-19  8:47 Paul Richards
  0 siblings, 0 replies; only message in thread
From: Paul Richards @ 2019-11-19  8:47 UTC (permalink / raw)
  To: linux-ext4

Hello there,
I'm trying to understand the interaction between the ext4 `commit`
interval option, and the `vm.dirty_expire_centisecs` tuneable.

The ext4 `commit` documentation says:

> Ext4 can be told to sync all its data and metadata every 'nrsec' seconds. The default value is 5 seconds. This means that if you lose your power, you will lose as much as the latest 5 seconds of work (your filesystem will not be damaged though, thanks to the journaling).

The `dirty_expire_centisecs` documentation says:

> This tunable is used to define when dirty data is old enough to be eligible for writeout by the kernel flusher threads. It is expressed in 100'ths of a second. Data which has been dirty in-memory for longer than this interval will be written out next time a flusher thread wakes up.

Superficially these sound like they have a very similar effect.  They
periodically flush out data that hasn't been explicitly fsync'd by the
application.  I'd like to understand a bit more the interaction
between these.

What happens when the ext4 commit interval is shorter than the
dirty_expire_centisecs setting?  (Does the latter become "redundant"?)

What happens when the dirty_expire_centisecs setting is shorter than
the ext4 commit interval?


^ permalink raw reply	[flat|nested] only message in thread

only message in thread, back to index

Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-11-19  8:47 Query about ext4 commit interval vs dirty_expire_centisecs Paul Richards

Linux-ext4 Archive on

Archives are clonable:
	git clone --mirror linux-ext4/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-ext4 linux-ext4/ \
	public-inbox-index linux-ext4

Example config snippet for mirrors

Newsgroup available over NNTP:

AGPL code for this site: git clone