Date: Tue, 1 Apr 2014 12:19:20 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Davidlohr Bueso <davidlohr@hp.com>,
        Manfred Spraul <manfred@colorfullife.com>, aswin@hp.com,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
        "Gotou, Yasunori" <y-goto@jp.fujitsu.com>,
        chenhanxiao <chenhanxiao@cn.fujitsu.com>,
        Gao feng <gaofeng@cn.fujitsu.com>
Subject: Re: [PATCH] ipc,shm: increase default size for shmmax
Message-Id: <20140401121920.50d1dd96c2145acc81561b82@linux-foundation.org>
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On Tue, 01 Apr 2014 15:29:05 +0900 Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:

> >
> > So their system will act as if they had set SHMMAX=enormous.  What
> > problems could that cause?
> >
> >
> > Look.  The 32M thing is causing problems.  Arbitrarily increasing the
> > arbitrary 32M to an arbitrary 128M won't fix anything - we still have
> > the problem.  Think bigger, please: how can we make this problem go
> > away for ever?
> >
> 
> Our middleware engineers has been complaining about this sysctl limit.
> System administrator need to calculate required sysctl value by making sum
> of all planned middlewares, and middleware provider needs to write "please
> calculate systcl param by....." in their installation manuals.

Why aren't people just setting the sysctl to a petabyte?  What problems
would that lead to?
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