[Bug 257314] FBSD 13 crash after some KDE parts crash supposing out of swap space

From: <bugzilla-noreply_at_freebsd.org>
Date: Sun, 25 Jul 2021 16:46:16 UTC

--- Comment #31 from Mark Millard <marklmi26-fbsd@yahoo.com> ---
(In reply to Michael from comment #30)

> in some way my pC became unusable, it's like
> slow motion all reactions on mouse or keyboard
> come after minutes (no exageration)

This is normal if the free RAM stays low and the
system is paging extensively to media that is not
fast for the purpose. Those are kinds of conditions
that can also eventually lead to the kills. One of
the tunables that I've indicated delays the kills,
making the conditions last longer in order to avoid
the kills.

But, until I can see the output lines of the
patched kernel I can not tell which of the 4
conditions are occurring. So, without that output
I've basically no chance to be of more help.

Also, as I've indicated before, we would need to
see top output from shortly before the kills happen
to see which processes are using what memory at the
time. Looking at top output after the kills start
does no good.

As for:

Solaris: WARNING: ignoring tunable zfs_arc_min (using 0 instead)
Solaris: WARNING: ignoring tunable zfs_arc_min (using 0 instead)

There is:

        /* Valid range: 32M - <arc_c_max> */
        if ((zfs_arc_min) && (zfs_arc_min != arc_c_min) &&
            (zfs_arc_min >= 2ULL << SPA_MAXBLOCKSHIFT) &&
            (zfs_arc_min <= arc_c_max)) {
                arc_c_min = zfs_arc_min;
                arc_c = MAX(arc_c, arc_c_min);
        WARN_IF_TUNING_IGNORED(zfs_arc_min, arc_c_min, verbose);

As far as I can tell this happens from having too little RAM
for the overall configuration, so that 32M is not even reasonable.
(But I'm no ZFS tuning expert.) With defaults, as I remember, the
standard recommendation is to have at least 8 GiBytes of RAM for
ZFS. For less, some ZFS tuning expertise is needed (that I do not

If you have done some zfs tuning, you should add notes to the
bugzilla about what your settings are and what the machine
has for RAM and such. Someone with ZFS tuning expertise might
comment based on such information.

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