Comment 20 for bug 1833281

I have 10Gb of RAM in this system and run Fedora 26. If I launch Cities:
Skylines with no swap space, things run well performance wise until I get an
OOM - and it all dies - which is expected.

When I turn on swap to /dev/sda2 which resides on an SSD, I get complete
system freezes while swap is being accessed.

The first swap was after loading a saved game, then launching kmail in the
background. This caused ~500Mb to be swapped to /dev/sda2 on an SSD. The
system froze for about 8 minutes - barely being able to move the mouse. The
HDD LED was on constantly during the entire time.

To hopefully rule out the above glibc issue, I started the game via jemalloc -
but experienced even more severe freezes while swapping. I gave up waiting
after 13 minutes of non-responsiveness - not even being able to move the mouse
properly.

During these hangs, I could typed into a Konsole window, and some of the
typing took 3+ minutes to display on the screen (yay for buffers?).

I have tested this with both the default vm.swappiness values, as well as the
following:
vm.swappiness = 1
vm.min_free_kbytes = 32768
vm.vfs_cache_pressure = 60

I noticed that when I do eventually get screen updates, all 8 cpus (4 cores /
2 threads) show 100% CPU usage - and kswapd is right up there in the process
list for CPU usage. Sadly I haven't been able to capture this information
fully yet due to said unresponsiveness.

(more to come in comments & attachments)