Changes

CRIU can detect what memory pages a task (or tasks) has changed since some moment of time. This page describes why this thing is required, how it works and how to use it.

CRIU can detect what memory pages a task (or tasks) has changed since some moment of time. This page describes why this is required, how it works and how to use it.

== Why do we need to track memory changed ==

== Why do we need to track memory changed ==

There are several scenarios when detecting what parts of memory has changed is required:

There are several scenarios where detecting what parts of memory has changed is required:

; [[Incremental dumps]]

; [[Incremental dumps]]

  # criu check --feature mem_dirty_track

  # criu check --feature mem_dirty_track

command should say the feature is supported. The memory changes tracking was initially merged into Linux kernel v3.11, and was further polished until v3.18.

command should say the feature is supported. The memory changes tracking was initially merged into Linux kernel v3.11, and was further polished until v3.18 (see [[Upstream kernel commits]] for details).

There are several command line options to use the functionality:

There are several command line options to use the functionality:

;<code>--prev-images-dir</code> option

;<code>--prev-images-dir</code> option

:This option says where the images from previous <code>dump</code> or <code>pre-dump</code> (see below) action reside. If possible, CRIU will not dump memory pages that hasn't changed since that time.

:This option is used to provide the path where images from a previous <code>dump</code> or <code>pre-dump</code> (see below) action reside. If possible, CRIU will dump only the memory pages that have been modified since that time.

;<code>--track-mem</code> option

;<code>--track-mem</code> option