On Fri 21-10-11 12:39:22, Glauber Costa wrote: > On 10/21/2011 03:41 AM, Ying Han wrote: > >On Wed, Oct 19, 2011 at 6:33 PM, Michal Hocko<mhocko@xxxxxxx> wrote: [...] > >>TODO [...] > >>- is bool sufficient. Don't we rather want something like priority > >> instead? [...] > >Hi Michal: > > > >I didn't read through the patch itself but only the description. If we > >wanna protect a memcg being reclaimed from under global memory > >pressure, I think we can approach it by making change on soft_limit > >reclaim. > > > >I have a soft_limit change built on top of Johannes's patchset, which > >does basically soft_limit aware reclaim under global memory pressure. > >The implementation is simple, and I am looking forward to discuss more > >with you guys in the conference. > > > >--Ying > I don't think soft limits will help his case, if I know understand > it correctly. Global reclaim can be triggered regardless of any soft > limits we may set. > > Now, there are two things I still don't like about it: > * The definition of a "main workload", "main cgroup", or anything > like that. This was just because I wanted to point out the particular case that I am interested in. You can of course setup more cgroups to be isolated and balance them by the soft limit. > I'd prefer to rank them according to some parameter, > something akin to swapiness. This would allow for other people to > use it in a different way, while still making you capable of > reaching your goals through parameter settings (i.e. one cgroup has > a high value of reclaim, all others, a much lower one) Yes, this has been mentioned in the patch TODO section (above). I wanted the first post to be as easy as possible for the discussion starter. I guess that we really need something like priority in fact. > > * The fact that you seem to want to *skip* reclaim altogether for a > cgroup. That's a dangerous condition, IMHO. What I think we should > try to achieve, is "skip it for practical purposes on sane > workloads". Yes the feature might be dangerous (we provide many ways to shoot self toes already ;)) but that is what you get if you want to guarantee something. But I agree, I guess we can be more clever and if it is priority based we can map isolation priorities to the reclaim priorities somehow. > Again, a parameter that when set to a very high mark, has the effect > of disallowing reclaim for a cgroup under most sane circumstances. > > What do you think of the above, Michal ? Yes I guess that priority based isolation is the way to go. We should, however, start with a consensus in this regard (should we do something like that at all?). Thanks -- Michal Hocko SUSE Labs SUSE LINUX s.r.o. Lihovarska 1060/12 190 00 Praha 9 Czech Republic -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>