From: Hugh Dickins <hugh.dickins@tiscali.co.uk>
To: Bill Speirs <bill.speirs@gmail.com>
Cc: Nick Piggin <npiggin@suse.de>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: vma_merge issue
Date: Wed, 12 Aug 2009 21:53:25 +0100 (BST) [thread overview]
Message-ID: <Pine.LNX.4.64.0908122143020.20776@sister.anvils> (raw)
In-Reply-To: <Pine.LNX.4.64.0908122038360.18426@sister.anvils>
On Wed, 12 Aug 2009, Hugh Dickins wrote:
>
> Don't use anonymous memory, have a 1GB sparse file to back this,
> and mmap it MAP_SHARED, then you won't get charged for RAM+swap.
A "refinement" to that suggestion is to put the file on tmpfs:
you will then get charged for RAM+swap as you use it, but you can
use madvise MADV_REMOVE to unmap pages, punching holes in the file,
freeing up those charges. A little baroque, but I think it does
amount to a way of doing exactly what you wanted in the first place.
(Note: we do insist on PROT_WRITE access at the time of MADV_REMOVE:
I've even a feeling it was me who insisted on that.)
Hugh
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next prev parent reply other threads:[~2009-08-12 20:53 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <a1b36c3a0908101347t796dedbat2ecb0535c32f325b@mail.gmail.com>
2009-08-12 18:26 ` Hugh Dickins
2009-08-12 19:04 ` Bill Speirs
2009-08-12 20:23 ` Hugh Dickins
2009-08-12 20:53 ` Hugh Dickins [this message]
2009-08-13 1:15 ` William R Speirs
2009-08-13 17:33 ` Hugh Dickins
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