OpenBSD Journal

Soft updates (softdep) disabled for future VFS work

Contributed by n/a on from the occams-razor-of-kernel-locking dept.

A low key leak from the ongoing g2k23 hackathon comes the news that soft updates (aka softdep) will, for now, be a no-op on OpenBSD-current.

The commit message by Bob Beck (beck@) reads,

From:       Bob Beck <beck () cvs ! openbsd ! org>
Date:       2023-07-05 15:13:28

Module name:	src
Changes by:	2023/07/05 09:13:28

Modified files:
	sys/kern       : vfs_syscalls.c 
	sys/sys        : mount.h 
	sys/ufs/ffs    : ffs_softdep.c ffs_vfsops.c 

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@

We look forward to further work and explanation of the motivation behind this change, sure to follow.

(Comments are closed)

  1. By Christoff Humphries (Christoff) on

    Curious, indeed. I'm definitely interested in what will be put in place of it. Not in a negative or dismissive manner, but one of learning and curiosity from folks way smarter and better at this stuff than I am.

    I'm not a filesystem or kernel expert by any means, but softdeps did give me warm fuzzies for filesystem reliability without having to recheck it on failure every time and waiting for the system to eventually boot.

  2. By John McCue (jmcunx) on

    I was always on the fence about the need of softdep based upon my usage. I enabled it because some people said yes, others said no (disabled on /).

    So, this will force me to see if I notice a difference with the next release :)

    But thanks, good to know

  3. By Marc Espie (espie) on

    The big issue with softdep is that it has tendrils everywhere, and since we didn't convince Kirk to move over to OpenBSD, it tends to be a big hindrance in fixing everything else instead of helping.

    The buffercache, the pagedaemon, the swapper, unlocking subsystems.

    Hopefully, all these have a chance of being done by a human with softdep gone.


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