Re: [patch] memcg: add oom killer delay

[KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

On Mon, 7 Mar 2011 21:30:19 -0800 (PST)
David Rientjes <rientjes@google.com> wrote:

> On Tue, 8 Mar 2011, KAMEZAWA Hiroyuki wrote:
> 
> > Hmm? That's an unexpected answer. Why system's capacity is problem here ?
> > (root memcg has no 'limit' always.)
> > 
> > Is it a problem that 'there is no 'guarantee' or 'private page pool'
> > for daemons ?
> > 
> 
> It's not an inherent problem of memcg, it's a configuration issue: if your 
> userspace application cannot respond to address an oom condition in a 
> memcg for whatever reason (such as it being in an oom memcg itself), then 
> there's a chance that the memcg will livelock since the kernel cannot do 
> anything to fix the issue itself.
> 
> That's aside from the general purpose of the new 
> memory.oom_delay_millisecs: users may want a grace period for userspace to 
> increase the hard limit or kill a task before deferring to the kernel.  
> That seems exponentially more useful than simply disabling the oom killer 
> entirely with memory.oom_control.  I think it's unfortunate 
> memory.oom_control was merged frst and seems to have tainted this entire 
> discussion.
> 

That sounds like a mis-usage problem....what kind of workaround is offerred
if the user doesn't configure oom_delay_millisecs , a yet another mis-usage ?

THanks,
-Kame

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