On Fri 14-02-20 08:57:28, Tejun Heo wrote: [...] Sorry to skip over a large part of your response. The discussion in this thread got quite fragmented already and I would really like to conclude to something. > > I believe I have already expressed the configurability concern elsewhere > > in the email thread. It boils down to necessity to propagate > > protection all the way up the hierarchy properly if you really need to > > protect leaf cgroups that are organized without a resource control in > > mind. Which is what systemd does. > > But that doesn't work for other controllers at all. I'm having a > difficult time imagining how making this one control mechanism work > that way makes sense. Memory protection has to be configured together > with IO protection to be actually effective. Please be more specific. If the protected workload is mostly in-memory, I do not really see how IO controller is relevant. See the example of the DB setup I've mentioned elsewhere. > As for cgroup hierarchy being unrelated to how controllers behave, it > frankly reminds me of cgroup1 memcg flat hierarchy thing I'm not sure > how that would actually work in terms of resource isolation. Also, I'm > not sure how systemd forces such configurations and I'd think systemd > folks would be happy to fix them if there are such problems. Is the > point you're trying to make "because of systemd, we have to contort > how memory controller behaves"? No, I am just saying and as explained in reply to Johannes, there are practical cases where the cgroup hierarchy reflects organizational structure as well. -- Michal Hocko SUSE Labs
