[Discuss] memory management

[Bill Ricker]

How Swap and Memory are used is controlled largely by the 'swappiness'
setting.  The default is correct for servers but not for workstations.

swap - How do I configure swappiness? - Ask Ubuntu
The Linux kernel provides a tweakable setting that controls how often
the swap file is used, called swappiness. A swappiness setting of zero
means that the disk will ...
askubuntu.com/questions/103915/how-do-i-configure-swapp...

SwapFaq - Community Help Wiki - Ubuntu
The hibernation implementation currently used in Ubuntu, swsusp, needs
a swap or suspend partition. ... The default setting in Ubuntu is
swappiness=60.
help.ubuntu.com/community/SwapFaq

On Fri, Jun 19, 2015 at 10:01 AM, Matthew Gillen <me at mattgillen.net> wrote:
> I'm looking for some advice on tuning my linux box's memory management.
>  I've got an older workstation that has merely 4GB of memory.  If I try
> to run Firefox, and a few java apps (e.g., Eclipse), my machine thrashes
> about and effectively locks up because of out-of-memory issues.
>
> For example: the mouse will continue to move, but won't change it's icon
> contextually.  If I hit cntl-alt-f2 and try to log in to a virtual
> console, mgetty will eventually ask for the username, but after I hit
> enter, it just hangs, not popping up the password prompt, and after 60
> seconds the login times out.  Trying to ssh into the machine from
> somewhere else ends up timing out.
>
> After going on like this for literally 10 minutes, OOM-killer sometimes
> kills the right thing (one of the two processes hogging the most memory:
> firefox or eclipse), and the machine becomes usable again sometime later.
>
> I have heftier workstations I can use, but this behavior is really
> frustrating to me, because I'd like to think linux does good memory
> management.  I've tried using huge swap (2x physical memory).  I've
> tried with virtually no swap (on the theory that without swap, there
> would be no thrashing and at least oom-killer would have to do its thing
> without locking up the machine for 10 minutes first).  The problem there
> was oom-killer making bad decisions about what to kill (e.g., the window
> manager, and then whatever out-of-control process is sucking up memory
> just sucks up whatever got freed, and nothing gets better).  At least
> with some swap oom-killer seems to make better guesses about who to murder.
>
> Does anyone have any tips on how to prevent linux from thrashing like
> that?  The behavior when low on memory seems atrociously bad.
>
> Thanks,
> Matt
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-- 
Bill Ricker
bill.n1vux at gmail.com
https://www.linkedin.com/in/n1vux