From: Andre Noll <maan@tuebingen.mpg.de>
Date: Sat, 30 Jan 2021 17:22:52 +0000 (+0100)
Subject: fs: Add subsection on ext4 fast commits.
X-Git-Url: http://git.tue.mpg.de/?a=commitdiff_plain;h=b9ec6d1a52723496b877ce2571ba1e017a746152;p=aple.git

fs: Add subsection on ext4 fast commits.
---

diff --git a/Filesystems.m4 b/Filesystems.m4
index 40dedd1..7750dab 100644
--- a/Filesystems.m4
+++ b/Filesystems.m4
@@ -829,6 +829,27 @@ it's best to make the LV slightly larger than necessary and then
 enlarge the filesystem to the maximal possible size by running
 <code>resize2fs(8)</code> without specifying the new size. </p>
 
+SUBSECTION(«Fast Commits»)
+
+<p>
+
+Optimization introduced in 2020 (Linux-5.10).
+
+activated at mkfs time
+
+light-weight journaling method
+
+Idea: parts of the metadata written to the log can instead be derived
+from the inode. Leads to more compact format.
+
+Implementation: additional journal for fast commits, i.e., for those
+operations that can be optimized. Contains changes at the *file* level
+
+<li> Check <code>/proc/fs/ext4/dev/fc_info</code> to see whether fast
+commits are supported in the runing kernel. </li>
+
+</p>
+
 EXERCISES()
 
 <ul>