On Thu 03-01-19 11:10:00, Yang Shi wrote: > > > On 1/3/19 10:53 AM, Michal Hocko wrote: > > On Thu 03-01-19 10:40:54, Yang Shi wrote: > > > > > > On 1/3/19 10:13 AM, Michal Hocko wrote: [...] > > > > Is there any reason for your scripts to be strictly sequential here? In > > > > other words why cannot you offload those expensive operations to a > > > > detached context in _userspace_? > > > I would say it has not to be strictly sequential. The above script is just > > > an example to illustrate the pattern. But, sometimes it may hit such pattern > > > due to the complicated cluster scheduling and container scheduling in the > > > production environment, for example the creation process might be scheduled > > > to the same CPU which is doing force_empty. I have to say I don't know too > > > much about the internals of the container scheduling. > > In that case I do not see a strong reason to implement the offloding > > into the kernel. It is an additional code and semantic to maintain. > > Yes, it does introduce some additional code and semantic, but IMHO, it is > quite simple and very straight forward, isn't it? Just utilize the existing > css offline worker. And, that a couple of lines of code do improve some > throughput issues for some real usecases. I do not really care it is few LOC. It is more important that it is conflating force_empty into offlining logic. There was a good reason to remove reparenting/emptying the memcg during the offline. Considering that you can offload force_empty from userspace trivially then I do not see any reason to implement it in the kernel. > > I think it is more important to discuss whether we want to introduce > > force_empty in cgroup v2. > > We would prefer have it in v2 as well. Then bring this up in a separate email thread please. -- Michal Hocko SUSE Labs
