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From: ebiederm@xmission.com (Eric W. Biederman)
To: Ingo Molnar <mingo@elte.hu>
Cc: Oleg Nesterov <oleg@tv-sign.ru>, Robin Holt <holt@sgi.com>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       Chris Snook <csnook@redhat.com>, linux-kernel@vger.kernel.org,
       Jack Steiner <steiner@americas.sgi.com>
Subject: Re: init's children list is long and slows reaping children.
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	<20070406163100.GA554@tv-sign.ru> <20070406173249.GA2517@elte.hu>
Date: Fri, 06 Apr 2007 12:30:18 -0600
In-Reply-To: <20070406173249.GA2517@elte.hu> (Ingo Molnar's message of "Fri, 6
	Apr 2007 19:32:49 +0200")
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Ingo Molnar <mingo@elte.hu> writes:

> no. Two _completely separate_ lists.
>
> i.e. a to-be-reaped task will still be on the main list _too_. The main 
> list is for all the PID semantics rules. The reap-list is just for 
> wait4() processing. The two would be completely separate.

And what pray tell except for heuristics is the list of children used for?

I could find a use in the scheduler (oldest_child and younger/older_sibling).
I could find a use in mm/oom_kill.

I could find a use in irixsig where it roles it's own version of wait4.

Perhaps I was blind but that was about it.

I didn't see the child list implementing any semantics we really care
about to user space.

Eric