Re: [PATCH] Add hierarchical accounting to cpu accountingcontroller

[KAMEZAWA Hiroyuki]

On Wed, 05 Nov 2008 11:31:32 +0800
Li Zefan <lizf@xxxxxxxxxxxxxx> 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

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/