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Scary things about Linux (was: Re: gnats user)


On Wed, Mar 07, 2018 at 02:13:07PM -0500, rhkramer@xxxxxxxxx wrote:
> On Wednesday, March 07, 2018 01:16:06 AM Reco wrote:
> > Along with other uid<100 users, 'gnats' is there for a long time,
> > nobody's sure what will break if it's removed from passwd(5), 
> Wow!  (I am not the OP, but that is disappointing (but not surprising, I 
> suspect the same or similar about other things buried in Linux one place or 
> another) and scary.

You want scary - I'll give you one. Have you ever thought what do these
number in uptime(1) mean?
If you thought 'a number of processes that's waiting for CPU' - think
again - [1]. And yes, only Linux kernel counts uninterruptible sleep as
load average.

As for the disappointment - I have it too. Fresh one:

Mar  7 09:11:17 xxx kernel: [315045.065234] systemd-udevd invoked
oom-killer: ...
Mar  7 09:11:18 xxx kernel: [315045.301642] Free swap  = 3887244kB
Mar  7 09:11:18 xxx kernel: [315045.305155] Total swap = 3903484kB
Mar  7 09:11:18 xxx kernel: [315045.308669] 65536 pages RAM

Use swap, they said. If you don't configure swap, big scary
out-of-memory killer will take your processes, they said.

[1] http://www.brendangregg.com/blog/2017-08-08/linux-load-averages.html