From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
To: David Rientjes <rientjes@google.com>
Subject: Re: [resend][PATCH 2/4] Revert "oom: deprecate oom_adj tunable"
Cc: kosaki.motohiro@jp.fujitsu.com, Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        LKML <linux-kernel@vger.kernel.org>, linux-mm <linux-mm@kvack.org>
In-Reply-To: <alpine.DEB.2.00.1011271737110.3764@chino.kir.corp.google.com>
References: <20101123160259.7B9C.A69D9226@jp.fujitsu.com> <alpine.DEB.2.00.1011271737110.3764@chino.kir.corp.google.com>
Message-Id: <20101130220221.832B.A69D9226@jp.fujitsu.com>
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Date: Tue, 30 Nov 2010 22:03:43 +0900 (JST)
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> On Tue, 23 Nov 2010, KOSAKI Motohiro wrote:
> 
> > > > No irrelevant. Your patch break their environment even though
> > > > they don't use oom_adj explicitly. because their application are using it.
> > > > 
> > > 
> > > The _only_ difference too oom_adj since the rewrite is that it is now 
> > > mapped on a linear scale rather than an exponential scale.  
> > 
> > _only_ mean don't ZERO different. Why do userland application need to rewrite?
> > 
> 
> Because NOTHING breaks with the new mapping.  Eight months later since 
> this was initially proposed on linux-mm, you still cannot show a single 
> example that depended on the exponential mapping of oom_adj.  I'm not 
> going to continue responding to your criticism about this point since your 
> argument is completely and utterly baseless.

No regression mean no break. Not single nor multiple. see?


> 
> > Again, IF you need to [0 .. 1000] range, you can calculate it by your
> > application. current oom score can be get from /proc/pid/oom_score and
> > total memory can be get from /proc/meminfo. You shouldn't have break
> > anything.
> > 
> 
> That would require the userspace tunable to be adjusted anytime a task's 
> mempolicy changes, its nodemask changes, it's cpuset attachment changes, 

All situation can be calculated on userland. User process can be know
their bindings.


> its mems change, a memcg limit changes, etc.  The only constant is the 
> task's priority, and the current oom_score_adj implementation preserves 
> that unless explicitly changed later by the user.  I completely understand 
> that you may not have a use for this.


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