On Fri, Mar 11, 2022 at 5:31 PM Jan Ziak <0xe2.0x9a.0x9b@gmail.com> wrote:
> If it helps, I can send you the complete list of all the 1.8 million
> extents. I am not sure how long it might take to obtain such a list.

It takes only a couple of minutes to get all extents by using xfs_io.
A text file containing the histogram of all the file's extents is
attached to this email.

I suggest we do the following steps:

1. Make a snapshot of the file's extents (extents1.txt)

2. Enable btrfs autodefrag, enable tracing

3.1. Make a snapshot of the file's extents (extents2.txt)

3.2. Save /sys/kernel/debug/tracing/trace (trace.txt)

4. Compute the difference between extents1.txt and extents2.txt

5. Compare extents-diff.txt and trace.txt, in order to determine why
the number of extents is increasing over time despite
btrfs-autodefrag's attempts to defragment the file

-Jan