From 50e42c9ddcc26e705c5059ff8d4713686f183c48 Mon Sep 17 00:00:00 2001 From: Radostin Stoyanov Date: Thu, 23 Feb 2023 12:55:01 +0000 Subject: [PATCH] Add documentation for --ghost-fiemap The --ghost-fiemap option was introduced with #1963. It enables an optimized algorithm based on fiemap ioctl that can reduce the number of syscalls used to checkpoint highly sparse ghost files. This option is enabled by default. It can be disabled with --no-ghost-fiemap when using SEEK_HOLE/SEEK_DATA is preferred. In addition, an automatic fallback to SEEK_HOLE/SEEK_DATA is used for filesystems that do not supporting fiemap. Co-authored-by: Pavel Tikhomirov Signed-off-by: Radostin Stoyanov --- Documentation/criu.txt | 7 +++++++ criu/crtools.c | 1 + 2 files changed, 8 insertions(+) diff --git a/Documentation/criu.txt b/Documentation/criu.txt index 294127050..0e7d19c4c 100644 --- a/Documentation/criu.txt +++ b/Documentation/criu.txt @@ -384,6 +384,13 @@ mount -t cgroup -o devices,freezer none devices,freezer 'size' may be postfixed with a *K*, *M* or *G*, which stands for kilo-, mega, and gigabytes, accordingly. +*--ghost-fiemap*:: + Enable an optimization based on fiemap ioctl that can reduce the + number of system calls used when checkpointing highly sparse ghost + files. This option is enabled by default, and it can be disabled + with *--no-ghost-fiemap*. An automatic fallback to SEEK_HOLE/SEEK_DATA + is used when fiemap is not supported. + *-j*, *--shell-job*:: Allow one to dump shell jobs. This implies the restored task will inherit session and process group ID from the *criu* itself. diff --git a/criu/crtools.c b/criu/crtools.c index ca9361977..94657f418 100644 --- a/criu/crtools.c +++ b/criu/crtools.c @@ -445,6 +445,7 @@ usage: " is inaccessible\n" " --link-remap allow one to link unlinked files back when possible\n" " --ghost-limit size limit max size of deleted file contents inside image\n" + " --ghost-fiemap enable dumping of deleted files using fiemap\n" " --action-script FILE add an external action script\n" " -j|--" OPT_SHELL_JOB " allow one to dump and restore shell jobs\n" " -l|--" OPT_FILE_LOCKS " handle file locks, for safety, only used for container\n"