[GTALUG] Swappiness

[Scott Sullivan]

On 2018-09-05 06:52 AM, o1bigtenor via talk wrote:
> On Tue, Sep 4, 2018 at 11:16 PM, Evan Leibovitch via talk
>> I was referring to this:
>>
>> https://en.m.wikipedia.org/wiki/Swappiness
>>
> Greetings
> 
> Article looks interesting except the systemd provisions are attributes and and
> are not mentioned. Bottom of  the article indicates a somewhat recent editing
> date but with no mention of systemd I have further questions.

Dee,

Swappiness is a tuning parameter of the kernels memory management 
algorithms. So there is no reason for systemd to be mentioned as systemd 
has nothing to do with how application memory is managed.

> The article
> mentions places to change 'swappiness' and I can find the actual file but there
> is nothing in the sysctl.conf (IIRC the name) file re: swappiness. Somehow I
> would prefer something that did refer to systemd foibles as well for a guide so
> as not to really pooch anything.

Your correctly that sysctl.conf is the correct place, for setting kernel 
tunables, at boot time. For run time use the sysctl command, or parts of 
/sys file system interface.

In general you can expect sysctl.conf to be very empty, because it 
should only contains kernel parameters you (our your distro) are 
altering from the defaults.
Additionally it would be impractical to list all of them in such a file.

1) New parameters are being add all the time as hardware drivers are 
updated, or subsystems mature.
2) Parameters are exposed in a dotted-tree (first.second.third_level) 
and parts of that try will be system specific based on the hardware 
enumerations.

eg.
net.ipv6.conf.eno1.forwarding and net.ipv6.conf.enp3s0.forwarding for my 
two network interfaces, eno1 and enp3s0.

$ sudo sysctl -a | wc -l
1499

-- 
Scott Sullivan