Messages in this thread | | | Date | Wed, 5 Nov 2008 12:48:54 +0900 | From | KAMEZAWA Hiroyuki <> | Subject | Re: [PATCH] Add hierarchical accounting to cpu accounting controller |
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On Wed, 05 Nov 2008 11:31:32 +0800 Li Zefan <lizf@cn.fujitsu.com> wrote:
> >> cpuacct was designed to count cpu usage of a group of tasks, and now some people > >> want it to also take child group's usage into account, so I think this is a feature > >> request but not a bug fix. > >> > > > > I disagree. The child is a part of the parent's hierarchy, and therefore > > its usage should reflect in the parent's usage. > > > > In memcg the child's usage doesn't reflect in its parent's usage. ;) > > Balbir just posted a patchset to add hierarchy support in memcg, and added memory.feature > to disable/enable this feature. Is it for performance only or also for keeping the user > interface/behavior unchanged?
The main reason is performance.
And one of memcg's purpose is isolating resource usage of groups. Sum of usage is not very important sometimes. (we have /proc/meminfo ;) Sum of usage can be easily calculcated by user land and we don't have to pay the cost for it in the kernel.
Thanks, -Kame
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