Date: Tue, 15 Jan 2008 11:20:27 +0000
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: kosaki.motohiro@jp.fujitsu.com, linux-mm@kvack.org,
       linux-kernel@vger.kernel.org, Marcelo Tosatti <marcelo@kvack.org>,
       Daniel Spang <daniel.spang@gmail.com>, Rik van Riel <riel@redhat.com>,
       Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [RFC][PATCH 3/5] add /dev/mem_notify device
Message-ID: <20080115112027.6120915b@lxorguk.ukuu.org.uk>
In-Reply-To: <20080115195022.11A3.KOSAKI.MOTOHIRO@jp.fujitsu.com>
References: <20080115100029.1178.KOSAKI.MOTOHIRO@jp.fujitsu.com>
	<20080115104619.10dab6de@lxorguk.ukuu.org.uk>
	<20080115195022.11A3.KOSAKI.MOTOHIRO@jp.fujitsu.com>
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On Tue, 15 Jan 2008 19:59:02 +0900
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> wrote:

> 
> > > the core of this patch series.
> > > add /dev/mem_notify device for notification low memory to user process.
> > 
> > As you only wake one process how would you use this API from processes
> > which want to monitor and can free memory under load. Also what fairness
> > guarantees are there...
> 
> Sorry, I don't make sense what you mean fairness.
> Could you tell more?

If you have two processes each waiting on mem_notify is it not possible
that one of them will keep being the one woken up and the other will
remain stuck ?

It also appears there is no way to wait for memory shortages (processes
that can free memory easily) only for memory to start appearing.
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