From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
To: David Rientjes <rientjes@google.com>
Subject: Re: [PATCH] Revert oom rewrite series
Cc: kosaki.motohiro@jp.fujitsu.com, Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        LKML <linux-kernel@vger.kernel.org>, Ying Han <yinghan@google.com>,
        Bodo Eggert <7eggert@web.de>, Mandeep Singh Baines <msb@google.com>,
        "Figo.zhang" <figo1802@gmail.com>
In-Reply-To: <alpine.DEB.2.00.1011271743180.3764@chino.kir.corp.google.com>
References: <20101123151731.7B7B.A69D9226@jp.fujitsu.com> <alpine.DEB.2.00.1011271743180.3764@chino.kir.corp.google.com>
Message-Id: <20101130220510.832E.A69D9226@jp.fujitsu.com>
MIME-Version: 1.0
Content-Type: text/plain; charset="US-ASCII"
Content-Transfer-Encoding: 7bit
Date: Tue, 30 Nov 2010 22:04:59 +0900 (JST)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 3087
Lines: 64

> On Tue, 23 Nov 2010, KOSAKI Motohiro wrote:
> 
> > > You may remember that the initial version of my rewrite replaced oom_adj 
> > > entirely with the new oom_score_adj semantics.  Others suggested that it 
> > > be seperated into a new tunable and the old tunable deprecated for a 
> > > lengthy period of time.  I accepted that criticism and understood the 
> > > drawbacks of replacing the tunable immediately and followed those 
> > > suggestions.  I disagree with you that the deprecation of oom_adj for a 
> > > period of two years is as dramatic as you imply and I disagree that users 
> > > are experiencing problems with the linear scale that it now operates on 
> > > versus the old exponential scale.
> > 
> > Yes and No. People wanted to separate AND don't break old one.
> > 
> 
> You're arguing on the behalf of applications that don't exist.

Why?
You actually got the bug report.


> 
> > > > 1) About two month ago, Dave hansen observed strange OOM issue because he
> > > >    has a big machine and ALL process are not so big. thus, eventually all 
> > > >    process got oom-score=0 and oom-killer didn't work.
> > > > 
> > > >    https://kerneltrap.org/mailarchive/linux-driver-devel/2010/9/9/6886383
> > > > 
> > > >    DavidR changed oom-score to +1 in such situation. 
> > > > 
> > > >    http://kerneltrap.org/mailarchive/linux-kernel/2010/9/9/4617455
> > > > 
> > > >    But it is completely bognus. If all process have score=1, oom-killer fall
> > > >    back to purely random killer. I expected and explained his patch has
> > > >    its problem at half years ago. but he didn't fix yet.
> > > > 
> > > 
> > > The resolution with which the oom killer considers memory is at 0.1% of 
> > > system RAM at its highest (smaller when you have a memory controller, 
> > > cpuset, or mempolicy constrained oom).  It considers a task within 0.1% of 
> > > memory of another task to have equal "badness" to kill, we don't break 
> > > ties in between that resolution -- it all depends on which one shows up in 
> > > the tasklist first.  If you disagree with that resolution, which I support 
> > > as being high enough, then you may certainly propose a patch to make it 
> > > even finer at 0.01%, 0.001%, etc.  It would only change oom_badness() to 
> > > range between [0,10000], [0,100000], etc.
> > 
> > No.
> > Think Moore's Law. rational value will be not able to work in future anyway.
> > 10 years ago, I used 20M bytes memory desktop machine and I'm now using 2GB.
> > memory amount is growing and growing. and bash size doesn't grwoing so fast.
> > 
> 
> If you'd like to suggest an increase to the upper-bound of the badness 
> score, please do so, although I don't think we need to break ties amongst 
> tasks that differ by at most <0.1% of the system's capacity.

No. I dislike. I dislike propotinal score.

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