Date: Thu, 11 May 2006 16:15:43 +0100 (BST)
From: Hugh Dickins <hugh@veritas.com>
To: Adam Litke <agl@us.ibm.com>
cc: Christoph Hellwig <hch@infradead.org>, linux-mm@kvack.kernel.org,
       linux-kernel@vger.kernel.org
Subject: Re: [RFC] Hugetlb demotion for x86
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On Wed, 10 May 2006, Adam Litke wrote:
> 
> Strict overcommit is there for shared mappings.  When private mapping

I presume that by "strict overcommit" you mean "strict no overcommit".

> support was added, people agreed that full overcommit should apply to
> private mappings for the same reasons normal page overcommit is desired.

I'm not sure how wide that agreement was.  But what I wanted to say is...

> For one: an application using lots of private huge pages should not be
> prohibited from forking if it's likely to just exec a small helper
> program.

This is an excellent use for madvise(start, length, MADV_DONTFORK).
Though it was added mainly for RDMA issues, it's a great way for a
program with a huge commitment to exclude areas of its address space
from the fork, so making that fork much more likely to succeed.

Hugh
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