Messages in this thread | | | Date | Sat, 31 May 2008 03:50:51 +0530 | From | Balbir Singh <> | Subject | Re: [RFC][PATCH 1/2] memcg: res_counter hierarchy |
| |
KAMEZAWA Hiroyuki wrote: > This patch tries to implements _simple_ 'hierarchy policy' in res_counter. > > While several policy of hierarchy can be considered, this patch implements > simple one > - the parent includes, over-commits the child > - there are no shared resource
I am not sure if this is desirable. The concept of a hierarchy applies really well when there are shared resources.
> - dynamic hierarchy resource usage management in the kernel is not necessary >
Could you please elaborate as to why? I am not sure I understand your point
> works as following. > > 1. create a child. set default child limits to be 0. > 2. set limit to child. > 2-a. before setting limit to child, prepare enough room in parent. > 2-b. increase 'usage' of parent by child's limit.
The problem with this is that you are forcing the parent will run into a reclaim loop even if the child is not using the assigned limit to it.
> 3. the child sets its limit to the val moved from the parent. > the parent remembers what amount of resource is to the children. >
All of this needs to be dynamic
> Above means that > - a directory's usage implies the sum of all sub directories + > own usage. > - there are no shared resource between parent <-> child. > > Pros. > - simple and easy policy. > - no hierarchy overhead. > - no resource share among child <-> parent. very suitable for multilevel > resource isolation.
Sharing is an important aspect of hierachies. I am not convinced of this approach. Did you look at the patches I sent out? Was there something fundamentally broken in them?
[snip]
-- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL
| |