swap space issues

[Donald Wilde]

On 6/24/20, Donald Wilde <dwilde1 at gmail.com> wrote:
> On 6/24/20, Greg 'groggy' Lehey <grog at freebsd.org> wrote:
>> On Wednesday, 24 June 2020 at  9:36:23 -0700, Donald Wilde wrote:
>>> All,
>>>
>>> I recently upgraded my 12-STABLE system to the latest, and now my
>>> swap subsystems aren't working. I deliberately set up a 40GB
>>> partition for swap, and when I do 'top -t' I am only seeing 7906M
>>> total.
>>
>> That looks suspiciously like the difference from 32 GB.  Could it be
>> numeric overflow?  And if so, where?  What does pstat -s say?
>>
>
> Well, hi Greg! LTNT2!
>
> pstat -shm:
>
> /dev/ada0s1b  65536 (1M blocks), Used: 1.5G, Avail: 63G, Capacity: 2%
>
> This is while synth is still running on openblas and openjdk8.
>
>>> When using synth, it shows swap usage of < 2%, but then it gives the
>>> 'out of swap' complaint and tosses all my users out into neverland.
>>
>> Unless this also causes kernel messages to that effect, this, too,
>> could be an issue with synth.
>
> I believe the messages about 'out of swap' were from the kernel as it
> died, not synth. As I say, it killed all my active users, both root
> and non-root.
>
> Why does _top_ show the 7906M number? I suspect that it's deeper than
> just synth.
>
> What else can I share to help diagnose this?

Let me try this: I can reduce kern.maxswzone to a number lower than 32G.

That won't _solve_ the underlying problem, but we can see if it
impacts both top and synth.

I just did portsnap fetch update and it came up with 300 patches, so
that should give us a good run!

[snip]

-- 
Don Wilde
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