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Date: Tue, 10 Apr 2007 03:07:01 -0400
From: Jeff Garzik <jeff@garzik.org>
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To: Linus Torvalds <torvalds@linux-foundation.org>
CC: Andrew Morton <akpm@linux-foundation.org>, Dave Jones <davej@redhat.com>,
       Robin Holt <holt@sgi.com>, "Eric W. Biederman" <ebiederm@xmission.com>,
       Ingo Molnar <mingo@elte.hu>, linux-kernel@vger.kernel.org,
       Jack Steiner <steiner@americas.sgi.com>
Subject: Re: init's children list is long and slows reaping children.
References: <20070405195118.GH22762@lnx-holt.americas.sgi.com> <4616CBF0.7090606@garzik.org> <20070409172339.48d661d6.akpm@linux-foundation.org> <20070410015912.GE1994@redhat.com> <20070409193056.6b52c354.akpm@linux-foundation.org> <Pine.LNX.4.64.0704091944580.6730@woody.linux-foundation.org>
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Linus Torvalds wrote:
> 
> On Mon, 9 Apr 2007, Andrew Morton wrote:
>>>    10 ?        S<     0:00 [khelper]
>> That one's needed to parent the call_usermodehelper() apps.  I don't think
>> it does anything else.  We used to use keventd for this but that had some
>> problem whcih I forget.
> 
> I think it was one of a long series of deadlocks. 
> 
> Using a "keventd" for many different things sounds clever and nice, but 
> then sucks horribly when one event triggers another event, and they depend 
> on each other. Solution: use independent threads for the events.

Nod.  That's the key problem with keventd.  Independent things must wait 
on each other.

That's why I feel thread creation -- cheap under Linux -- is quite 
appropriate for many of these situations.

	Jeff