[Semibug] OpenBSD To depreciate soft updates

[Nick Holland]

On 7/6/23 10:27, Kyle Willett wrote:
> Hi everyone,
> 
> Hope everyone is well.  So I'm part of this group on Facebook called
> OpenBSD newbies ran by the same Peter Hansteen that did that wonderful
> talk earlier in the year or last year I can't remember and he shared
> this link: https://undeadly.org/cgi?action=article;sid=20230706044554
> 
> Basically in order to make FFS/UFS faster they have to remove soft
> updates.  Doesn't look like any user facing changes are made since
> they made that mount option in fstab just a no op so it does nothing
> in -CURRENT.

I think you misinterpreted the commit message:


    Log message:
    Make softdep mounts a no-op

    Softdep is a significant impediment to progressing in the vfs layer
    so we plan to get it out of the way. It is too clever for us to
    continue maintaining as it is.

    ok kettenis@ kn@ tobhe@ and most of the g2k23 room except bluhm@


> Just saw that yesterday and thought anyone running -CURRENT or the
> next release in October of OpenBSD should know.

"Impediment to progressing" does not necessarily mean "making it
faster"...in fact, turning off softdeps is going to really hurt
me on a few things (and leave a few other things "To Be Determined").
I suspect the goal is "making it better", which can have a lot
of interpretations, performance probably will not be the first.

The softdep code is very complicated.  Some developers have
maintained for years that there are bugs in it, but the code
is too scary (and the bugs too "edge case" and infrequent) to
get people interested in looking at it.

I'm not sure what advancements they are looking at, but having
heard a lot of developers grumble about working on file system
code for a lot of years, yeah, I get the idea of simplifying.
And maybe some of the soft update benefits can be gained once
they remove existing code and start fresh.

But yeah, that's a change to know about. I'm upgrading one of
my machines I suspect may have performance issues now to find out,
and I'll be upgrading the Toronto mirrors this weekend (the
mirrors will have NO performance issue with the loss of soft
updates, at least that you on the outside world will experience.
Might annoy me a bit when moving things around).

(upgrade just finished, all looks good, softdep is still in the
fstab file but mount is showing no softdep options on the mounted
file systems.  If I wasn't aware this was happening, I'd never
have noticed...so far. :) )

Nick.