Out of swap - NOT

Sat Feb 11 21:46:08 UTC 2017

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On Sat, 11 Feb 2017 07:54:10 -0600
Karl Denninger <karl at denninger.net> wrote:

> 
> In all probability it's really out.  Remember that RAM allocation has
> to either come from physical RAM or swap.  If the requested allocation
> cannot be made then you get this exact situation, and it happens
> quickly enough that you won't see it most of the time with monitoring
> tools.
> 
> What's probably biting you is temporary file space, which comes from
> RAM since it's mounted on a ramdisk, and exhausts it.  I've run into
> this same situation trying to build on a Pi2.
> 
> My recommendation? Connect a USB disk drive to the system and put a
> swap partition on there. Or cross-compile (which is what I do) on a
> nice big AMD64 box since that is MUCH faster.
> 
Greeting-

I find it really hard to believe that I could be running out of swap,
but I suppose as a test I can stick additional swap on my USB drive.
There is already as I said 3xRam swap on the sd card.  Yes perhaps my
pstat did not run at the exact right instant to see the OOM happen, but
having started on PDP 11/70s running BSD 4.1 I have never seen a kernel
build actually take that much memory.

This exercise is not really about getting a new kernel built.  Yes I
could cross on my Mac or one of my FreeBSD servers.  It is about
beating on the system to see what it can do and how stable it is.  When
last I beat on USB disks under FreeBSD ARM the disks would just
disappear as far as the kernel was concerned.  So I see there is much
improvement between 10 and 12.  

This really begs the question how can my 586 at 133Mhz with 48M of ram
and 96M  of swap build it's kernel (freebsd) and an arm box with more
real ram and 3x swap gets OOM issues?

- -Brett

- -- 

wynkoop at wynn.com
917-642-6925
929-272-0000

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