X is consuming ~100 GiB of RAM(!)

Tue Dec 5 18:14:05 UTC 2017

To Whom It May Concern:

Hello everybody. My name is Ewen and I am new to this distribution list.

So let me start with a little bit of background and the problem statement
of what I am seeing/encountering.

I am running a SuperMicro Server 6027TR-HTRF (
https://www.supermicro.com/products/system/2u/6027/sys-6027tr-htrf.cfm)
(which uses a Matrox G200eW graphics chip and it has four half-width nodes,
each node has two processor, each processor is an Intel Xeon E5-2690 (v1)
(8-core, 2.9 GHz stock, HTT disabled) running SuSE Linux Enterprise Server
12 SP1 (SLES 12 SP1).

Here are some of the outputs from the system:

ewen at aes4:~> X -version

X.Org X Server 1.15.2
Release Date: 2014-06-27
X Protocol Version 11, Revision 0
Build Operating System: openSUSE SUSE LINUX
Current Operating System: Linux aes4 3.12.49-11-default #1 SMP Wed Nov 11
20:52:43 UTC 2015 (8d714a0) x86_64
Kernel command line: BOOT_IMAGE=/boot/vmlinuz-3.12.49-11-default
root=UUID=fc4dcdb9-2468-422c-b29f-8da42fd7dec0
resume=/dev/disk/by-uuid/1d5d8a9c-218e-4b66-b094-f5154ab08434 splash=silent
quit showopts crashkernel=123M,high crashkernel=72M,low
Build Date: 12 November 2015  01:23:55AM

Current version of pixman: 0.32.6
         Before reporting problems, check http://wiki.x.org
         to make sure that you have the latest version.
ewen at aes4:~> uname -a
Linux aes4 3.12.49-11-default #1 SMP Wed Nov 11 20:52:43 UTC 2015 (8d714a0)
x86_64 x86_64 x86_64 GNU/Linux

The problem that I am having is that I am running a CAE analysis
application and during the course of the run, X will eventually consume
close to 100 GiB of RAM (out of 125 GiB installed)

ewen at aes4:~> date
Tue Dec 5 05:08:28 EST 2017
ewen at aes4:~> ps aux | grep Xorg
root 2245 7.7 79.0 271100160 104332316 tty7 Ssl+ Nov25 1078:19
/usr/bin/Xorg :0 -background none -verbose -auth /run/gdm/aut
h-for-gdm-9L7Ckz/database -seat seat0 -nolisten tcp vt7
ewen 11769 0.0 0.0 10500 944 pts/1 R+ 05:08 0:00 grep --color=auto Xorg

This does not occur when I perform the same analysis in runlevel 3 and when
I switch back to runlevel 5 and I am using GNOME for the desktop
environment, regardless of whether I initiate the analysis via a Terminal
inside GNOME or I ssh into the system (via cygwin from a Windows box), the
host server's X memory usage will continually increase as the analysis
progresses.

In trying to research this issue, I have found that I can either restrict
the amount of cache that X does via ulimit -m (Source:
https://wiki.ubuntu.com/X/Troubleshooting/HighMemory) or I can edit
xorg.conf by adding this option:

Option "XaaNoPixmapCache"

(Source: https://www.x.org/releases/current/doc/man/man5/xorg.conf.5.xhtml)

Would that be the recommended solution to the problem that I am
experiencing with X?

A couple of other notes:

ewen at aes4:~> free -g
             total       used       free     shared    buffers     cached
Mem:           125        125          0          0          0          3
-/+ buffers/cache:        122          3
Swap:          256        170         85
ewen at aes4:~> cat /proc/sys/vm/vfs_cache_pressure
200

Your help and commentary would be greatly appreciated. Thank you.

Sincerely,

Ewen Chan
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