Re: [RFC][PATCH 1/5] memcg: change for softlimit.

Balbir Singh
2009-08-28T14:46:57Z

* KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> [2009-08-28 23:40:56]:

> KAMEZAWA Hiroyuki wrote:
> > Balbir Singh wrote:
> >> But Bob and Mike might need to set soft limits between themselves. if
> >> soft limit of gold is 1G and bob needs to be close to 750M and mike
> >> 250M, how do we do it without supporting what we have today?
> >>
> > Don't use hierarchy or don't use softlimit.
> > (I never think fine-grain soft limit can be useful.)
> >
> > Anyway, I have to modify unnecessary hacks for res_counter of softlimit.
> > plz allow modification. that's bad.
> > I postpone RB-tree breakage problem, plz explain it or fix it by yourself.
> >
> I changed my mind....per-zone RB-tree is also broken ;)
>
> Why I don't like broken system is a function which a user can't
> know/calculate how-it-works is of no use in mission critical systems.
>
> I'd like to think how-to-fix it with better algorithm. Maybe RB-tree
> is not a choice.
>

Soft limits are not meant for mission critical work :-) Soft limits is
best effort and not a guaranteed resource allocation mechanism. I've
mentioned in previous emails how we recover if we find the data is
stale

--
Balbir