On Thu, Jun 3, 2021 at 7:38 PM Chris Down <chris@xxxxxxxxxxxxxx> wrote: > > yulei zhang writes: > >Thanks. IMHO, there are differences between these two throttlings. > >memory.high is a per-memcg throttle which targets to limit the memory > >usage of the tasks in the cgroup. For the memory allocation speed throttle(MST), > >the purpose is to avoid the memory burst in cgroup which would trigger > >the global reclaim and affects the timing sensitive workloads in other cgroup. > >For example, we have two pods with memory overcommit enabled, one includes > >online tasks and the other has offline tasks, if we restrict the memory usage of > >the offline pod with memory.high, it will lose the benefit of memory overcommit > >when the other workloads are idle. On the other hand, if we don't > >limit the memory > >usage, it will easily break the system watermark when there suddenly has massive > >memory operations. If enable MST in this case, we will be able to > >avoid the direct > >reclaim and leverage the overcommit. > > Having a speed throttle is a very primitive knob: it's hard to know what the > correct values are for a user. That's one of the reasons why we've moved away > from that kind of tunable for blkio. > > Ultimately, if you want work-conserving behaviour, why not use memory.low? Thanks. But currently low and high are for cgroup v2 setting, do you think we'd better extend the same mechanism to cgroup v1?
