linux-kernel - Re: [PATCH 1/5] staging: android: lowmemorykiller: Add config option to support oom

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Message-ID: <alpine.DEB.2.02.1302271509230.24485@chino.kir.corp.google.com>
Date:	Wed, 27 Feb 2013 15:12:55 -0800 (PST)
From:	David Rientjes <rientjes@...gle.com>
To:	Arve Hjønnevåg <arve@...roid.com>
cc:	John Stultz <john.stultz@...aro.org>,
	lkml <linux-kernel@...r.kernel.org>,
	Android Kernel Team <kernel-team@...roid.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH 1/5] staging: android: lowmemorykiller: Add config option
 to support oom_adj values

On Wed, 27 Feb 2013, Arve Hjønnevåg wrote:

> > Umm, writes to /proc/pid/oom_adj already are converted to the
> > /proc/pid/oom_score_adj scale linearly.  Heavy NACK to this patch since
> > oom_adj is completely deprecated.
> 
> I know it is deprecated, but your change, staging: android,
> lowmemorykiller: convert to use oom_score_adj, broke existing
> user-space code that still write to /proc/pid/oom_adj. This option
> lets you build a kernel that supports our user-space code until that
> user-space has been converted to use /proc/pid/oom_score_adj.
> 

As stated, writes to /proc/pid/oom_adj already are converted to a linear 
scale and stored in /proc/pid/oom_score_adj.  This is done with

	oom_adj == 15	->	oom_score_adj = 1000
	oom_adj != 15	->	oom_score_adj = (oom_adj * -1000) / -17

since the maximum oom_score_adj is 1000 and the minimum oom_adj is -17.

How does this not work as needed?