Comment # 72 on bug 1159882 from Michal Hocko

(In reply to Robert Delahunt from comment #71)
> My latest test monitoring /sys/fs/cgroup/memory was with the OpenSUSE LEAP
> 15.2 stock (update) kernel (see uname -a in previous post).

OK, that explains it, I guess. Please stick with the test kernel so that we can
actually draw any conclusion here. So far I believe that the two identified
patches have made swapping much more probable under stream IO. Upstream kernel
behaves differently because of later changes. The state we have in 15.2 kernels
is half baked and therefore I would rather like to restore the previous
behavior.
For that I would like to see confirmed that
a) test kernel (the latest one) doesn't swap under your streaming IO load
without cgroups (cgroup_disable=memory) and that this is the case consistently
in several runs
b) the same tested _without_ cgroup_disable=memory parameter - aka cgroups
enabled by default (check the cgroup hierarchy find /sys/fs/cgroup/memory -type
d)

in both cases collect /prov/vmstat as before