[… personal attacks against Didier omitted …]

I recommend to go back to basic netiquette. Attacking others in person
is not going to help anyone, nor does it add to a friendly community
around Devuan.

Alessandro Selli - 22.11.18, 21:55:
> You are again blockheadedly ignoring the fact that read-only is
> *NOT* the only setting that make sense changing on the /usr
> filesystem! There are several, and I already *twice* listed a few of
> them: nobarrier, noatime, iversion, nodev, etc etc.

barrier related mount options are deprecated, well even removed at least
for XFS, deprecated in 4.10 and and removed in 4.19¹. Write barriers
have been replaced by explicit cache flushes² (somewhere around 2.6.39…
I am too lazy to look it up in my Linux Performance tuning and analysis
training slides right now). But with kernels still supporting the mount
option, nobarrier or barrier=0 would have been simply dangerous for data
integrity unless you have made sure that no sudden write interruption by
for example power loss can happen. Cause it would cause journaling
filesystems to be unable to met strict write ordering demands that are
required for journaling to actually work reliably. By doing so, you
could basically also run Ext4 without journal at all, in order to
optimize performance. There are use cases for that, but if you
appreciate your filesystem integrity even in a case of power loss… I'd
recommend not doing so.

[1] xfs: remove deprecated barrier/nobarrier mount options
https://patchwork.kernel.org/patch/10487561/

[2] Jonathin Corbet,The end of block barriers:
https://lwn.net/Articles/400541/

Ciao,
--
Martin