Comment 1 for bug 2020139

By changing the CHUNKSIZE from 64 KiB to 1 MiB, it looks like the CPU was used more efficiently and it does the trick.

2023-05-17 11:54:23.080 376143 DEBUG cinder.image.image_utils [req-8228848b-f037-4a6a-802e-de7ffe62bae6 a32b8e6ed20f484eba8ddae8f7b6eb1e 08dd29cd8676470c8e0b73d2667f8cf0 - - -] Image fetch details:
 dest /var/lib/cinder/conversion/image_fetch_741953c3-08f7-43b6-b423-2be938ac8d02_gnmu2b9ycinder@cinder-ceph, size 1907.35 MB, duration 14.44 sec fetch /usr/lib/python3/dist-packages/cinder/image/i
mage_utils.py:639
2023-05-17 11:54:23.080 376143 INFO cinder.image.image_utils [req-8228848b-f037-4a6a-802e-de7ffe62bae6 a32b8e6ed20f484eba8ddae8f7b6eb1e 08dd29cd8676470c8e0b73d2667f8cf0 - - -] Image download 1907.3
5 MB at 132.10 MB/s

-> 1,057 Mbps

`openstack image save` with openstacksdk has a similar issue so I reported it separately as:
https://storyboard.openstack.org/#!/story/2010759