Hello, Glauber.

On Thu, Sep 27, 2012 at 02:29:06AM +0400, Glauber Costa wrote:

And then what? If you want a different behavior you need to go kill all
your services that are using memcg so you can get the behavior you want?
And if they happen to be making a specific flag choice by design, you
just say "you really can't run A + B together" ?

I myself think global switches are an unnecessary complication. And let
us not talk about use_hierarchy, please. If it becomes global, it is
going to be as part of a phase out plan anyway. The problem with that is
not that it is global, is that it shouldn't even exist.

I would consider it more of a compatibility thing which is set during
boot and configurable by sysadmin.  Let the newer systems enable it by
default on boot and old configs / special ones disable it as
necessary.

quoted

Backward compatibility is covered with single switch and I really
don't think "you can enable limits for kernel memory anytime but we
don't keep track of whatever happened before it was flipped the first
time because the first time is always special" is a sane thing to
expose to userland.  Or am I misunderstanding the proposed behavior
again?

You do keep track. Before you switch it for the first time, it all
belongs to the root memcg.

Well, that's really playing with words.  Limit is per cgroup and
before the limit is set for the first time, everything is accounted to
something else.  How is that keeping track?

The proposed behavior seems really crazy to me.  Do people really
think this is a good idea?

Thanks.

-- 
tejun

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