Re: [RFC][PATCH 2/3] memcg:: seq_ops support for cgroup

From: KAMEZAWA Hiroyuki
Date: Wed May 21 2008 - 02:01:35 EST

On Tue, 20 May 2008 22:06:48 -0700
"Paul Menage" <menage@xxxxxxxxxx> wrote:

> >
> > And (*read) method isn't useful ;)
> >
> > Can we add new stat file dynamically ?
> Yes, there's no reason we can't do that. Right now it's not possible
> to remove a control file without deleting the cgroup, but I have a
> patch that supports removal.
Good news. I'll wait for.

> The question is whether it's better to have one file per CPU/node or
> one large complex file.
For making the kernel simple, one-file-per-entity(cpu/node...) is better.
For making the applications simple, one big file is better.

I think recent interfaces uses one-file-per-entity method. So I vote for it
for this numastat. One concern is size of cpu/node. It can be 1024...4096 depends
on environment.

open/close 4096 files took some amount of cpu time.
(And that's why 'ps' command is slow on big system.)


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