Mailinglist Archive: opensuse-support (176 mails)

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Re: [opensuse-support] Unresponsive desktop - swapoff experiment
On 13/02/2019 17.39, Dave Howorth wrote:
On Wed, 13 Feb 2019 14:40:05 +0100 (CET) "Carlos E. R." <...@telefonica.net>
wrote:
I then killed Firefox and Thunderbird, restarted them (the machine
has to run my usual workload), then repeated the swapoff experiment.

Telcontar:~/Documents/lists/swapoff_test # time swapoff -a

real 3m30.374s
user 0m0.001s
sys 3m3.646s
Telcontar:~/Documents/lists/swapoff_test #

I was writing my notes on the terminal, when the system *collapsed*
and would not respond. I managed to issue "swapon -a" on an ssh
session already opened on another machine, which took perhaps half an
hour to process.

Yay! I'm happy you tried that trick and it worked :)

No, it did not work: it crashed, as I thought it would.
But I said that I would try nonetheless and I did.


Then, with swap back on, the system responded, after
also doing some OOM (on mysqld). Thunderbird was not running:
...

Interestingly, both mysqld and Thunderbird have been killed
differently (one by oom-killer, another by oom_reaper) Why mysqld I
have no idea, but it could have been worse.

mysqld is infamous for being chosen. oom-reaper is a relatively recent
addition to the oom killer (from suse) There's a good discussion at
https://lwn.net/Articles/668126/

[snip] TL;DR

Curious.

Well, Thunderbird had an email in writing. I had to recover it from the
draft folder.


As you can see, it is not possible to run this 8GiB machine without
Swap - I said it would not work and I was right.

I think what you've proved is that the machine cannot support the
workload. You either need to change the machine or the workload.

Neither is possible, unless I get donations ;-P

I had to spend money on house repairs, crumbling walls and such. The
washing machine refuses to tumble since this weekend, and the fridge
controller module is dying - replacement is too expensive and not worth
it on a 15 year machine. So I have to replace both machines.

At the moment I have more pressing needs rather than replacing the
motherboard + cpu + ram.

The workload - well, Firefox has too many tabs and windows, which is why
I asked about a tab archiver some weeks ago.



The machine is very responsive using swap on SSD. After all, swap was
invented decades ago precisely to avoid installing more RAM. The problem
is some race condition that the current kernel doesn't handle well (the
kernel in 42.3 did not have this problem).


]> Tasks: 448 total, 3 running, 444 sleeping, 0 stopped, 1 zombie
]> %Cpu(s): 14,5 us, 2,1 sy, 0,0 ni, 76,7 id, 6,7 wa, 0,0 hi, 0,0
si, 0,0 st
]> KiB Mem : 8161400 total, 712648 free, 5685608 used, 1763144
buff/cache
]> KiB Swap: 25165820 total, 23227900 free, 1937920 used. 1675796
avail Mem

1.6 GB available, that's good. Less than CPU 18% load.

# uptime
19:49:46 up 8 days 5:55, 4 users, load average: 0.39, 0.65, 0.68



You might be able to find a browser that uses less memory (or tune FF),
dunno. You might be able to find a way to work with less pages open.

You can almost certainly find a MUA that uses less memory then
Thunderbird. My first thought is claws, of course :) But there are many
other possibilities.

Not as user friendly. Yes, I also use Alpine. I need to see graphics and
photos often.


Or you could move one or other process(es) to some other machine and
remote the interface to your current machine, so it is merely serving
as the display for that process.

No, but I can move some services to another machine, classical
client-server setup.

--
Cheers / Saludos,

Carlos E. R.
(from 15.0 x86_64 at Telcontar)

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