Date: Fri, 15 Aug 2003 22:19:37 +0100
From: Jamie Lokier <jamie@shareable.org>
To: mouschi@wi.rr.com, linux-kernel@vger.kernel.org
Subject: Re: Interesting VM feature?
Message-ID: <20030815211937.GA20208@mail.jlokier.co.uk>
References: <147bb3140e7a.140e7a147bb3@rdc-kc.rr.com> <20030815200020.GM1027@matchmail.com>
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Mike Fedyk wrote:
> On Fri, Aug 15, 2003 at 02:56:02PM -0500, mouschi@wi.rr.com wrote:
> > Is madvise required to result in zero filled pages
> > by a standard, or is this just the commonly accepted
> > behavior?
> 
> I believe it is the standard for clean pages, though someone else will have
> to point out where...

That's the answer to a different question.

The unanswered question is: what should madvise(MADV_DONTNEED) do,
given dirty pages?

man madvise(*) says that it zero-fills anonymous private mappings, and
restores private file-backed mappings to the original file pages.

That is not surprising, as the CPU-friendly semantic is more
complicated to implement, needing an extra flag in the page table
(or rmap structure).

-- Jamie
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