Small server hanging after some days - top, load avg and Mem buff/cache question

From	"B.M." <b-misc@gmx.ch>
Newsgroups	linux.debian.user
Subject	Small server hanging after some days - top, load avg and Mem buff/cache question
Date	2024-10-28 11:50 +0100
Message-ID	<JCvtU-4Qpi-5@gated-at.bofh.it> (permalink)
Organization	linux.* mail to news gateway

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Hi,

I have a small server (Raspberry Pi 4 in fact) and since a couple of weeks it
repeatedly hangs after some days until I reboot it (after months of uptime
without any problem - but I changed a few things in the meantime, so maybe
load is now higher than before).

At least after installing watchdog it reboots now automatically.

Here some top output just before reboot:

load avg 20 18 12 (so: much higher than normal, e.g. 1.1 1.2 1.5 or so)
MiB Mem: 3835 total, 618 free, 1194 used, 2264 buff/cache
MiB Swap: 1024 total, 600 free, 430 used, 2640 avail

Processes with highest CPU usage:
kswapd0 with 80%
java (openhab) 41%
kworker/08:10+events_unbound 21%
pg_dump 18%

Processes with highest Mem usage:
java (i.e. openhab) with 626678 virt, 22%
postgres 338824 virt
postgre 338800 virt

From my understanding, there is enough memory available, even swap usage
wouldn't be necessary, since buff/cache is about 50% of physical memory. Is
this correct? But than: why is it going to hang afterwards, or why this
extreme load?

The only swap device available is zram, no swap partition, no swap file. The
system runs on btrfs.

Any ideas?

Thank you,
Bernd

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Thread

Small server hanging after some days - top,  load avg and Mem buff/cache question "B.M." <b-misc@gmx.ch> - 2024-10-28 11:50 +0100
  Re: Small server hanging after some days - top, load avg and Mem  buff/cache question "Alexander V. Makartsev" <avbetev@gmail.com> - 2024-10-28 12:40 +0100
  Re: Small server hanging after some days - top, load avg and Mem  buff/cache question Dan Ritter <dsr@randomstring.org> - 2024-10-28 15:40 +0100
    Re: Small server hanging after some days - top,  load avg and Mem buff/cache question "B.M." <b-misc@gmx.ch> - 2024-10-28 15:40 +0100
      Re: Small server hanging after some days - top, load avg and Mem  buff/cache question Dan Ritter <dsr@randomstring.org> - 2024-10-28 16:10 +0100

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