On Fri, Apr 24, 2020 at 5:13 AM Roman Gushchin <guro@xxxxxx> wrote: > > On Thu, Apr 23, 2020 at 04:33:23PM +0100, Chris Down wrote: > > Hi Yafang, > > > > I'm afraid I'm just as confused as Michal was about the intent of this patch. > > > > Can you please be more concise and clear about the practical ramifications > > and demonstrate some pathological behaviour? I really can't visualise what's > > wrong here from your explanation, and if I can't understand it as the person > > who wrote this code, I am not surprised others are also confused :-) > > > > Or maybe Roman can try to explain, since he acked the previous patch? At > > least to me, the emin/elow behaviour seems fairly non-trivial to reason > > about right now. > > Hi Chris! > > So the thing is that emin/elow cached values are shared between global and > targeted (caused by memory.max) reclaim. It's racy by design, but in general > it should work ok, because in the end we'll reclaim or not approximately > the same amount of memory. > > In the case which Yafang described, the emin value calculated in the process > of the global reclaim leads to a slowdown of the targeted reclaim. It's not > a tragedy, but not perfect too. It seems that the proposed patch makes it better, > and as now I don't see any bad consequences. > Thanks for your explanation. Your explanation make the issue more clear. If you don't mind, I will copy some of your comments to improve the commit log. -- Thanks Yafang
