After a fix to glibc that fixed Unity 3D based games (Fedora ref: https://
bugzilla.redhat.com/show_bug.cgi?id=1440287), I have noticed that when I play
Cities: Skylines that the system becomes unresponsive when digging into swap.
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
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
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.
This seems to be a relatively new problem that I did not encounter during the
Fedora 26 beta - but do now.
Forgot to add kernel version!
Currently testing with:
Related bug reports:
We apologize for the inconvenience. There is a large number of bugs to go through and several of them have gone stale. The kernel moves very fast so bugs may get fixed as part of a kernel update. Due to this, we are doing a mass bug update across all of the Fedora 26 kernel bugs.
Fedora 26 has now been rebased to 4.15.4-200.fc26. Please test this kernel update (or newer) and let us know if you issue has been resolved or if it is still present with the newer kernel.
If you have moved on to Fedora 27, and are still experiencing this issue, please change the version to Fedora 27.
If you experience different issues, please open a new bug report for those.
it still happens with Fedora 28
I don't have a system I can randomly remove RAM from now to test. My current system is unhappy running on a single RAM stick.
Report above still says it occurs, so I would say this is still an issue in recent kernels.
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