From: Christoph Lameter <clameter@sgi.com>
To: Andrew Morton <akpm@osdl.org>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC] Track mlock()ed pages
Date: Fri, 26 Jan 2007 10:23:44 -0800 (PST) [thread overview]
Message-ID: <Pine.LNX.4.64.0701261021200.7848@schroedinger.engr.sgi.com> (raw)
In-Reply-To: <20070126101027.90bf3e63.akpm@osdl.org>
On Fri, 26 Jan 2007, Andrew Morton wrote:
> > Large amounts of mlocked pages may be a problem for
> >
> > 1. Reclaim behavior.
> >
> > 2. Defragmentation
> >
>
> We know that. What has that to do with this patch?
Knowing how much mlocked pages are where is necessary to solve these
issues.
> > > You could perhaps go for a walk across all the other vmas which presently
> > > map this page. If any of them have VM_LOCKED, don't increment the counter.
> > > Similar on removal: only decrement the counter when the final mlocked VMA
> > > is dropping the pte.
> >
> > For that we would need an additional refcount for vmlocked maps in the
> > page struct.
>
> No you don't. The refcount is already there. It is "the sum of the VM_LOCKED
> VMAs which map this page".
>
> It might be impractical or expensive to calculate it, but it's there.
Correct. Its so expensive that it cannot be used to build vm stats for
mlocked pages. F.e. Determination of the final mlocked VMA dropping the
page would require a scan over all vmas mapping the page.
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next prev parent reply other threads:[~2007-01-26 18:23 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-01-26 5:43 [RFC] Track mlock()ed pages Christoph Lameter
2007-01-26 6:30 ` Nick Piggin
2007-01-26 6:36 ` Christoph Lameter
2007-01-26 11:13 ` Andrew Morton
2007-01-26 12:00 ` Nick Piggin
2007-01-26 15:44 ` Christoph Lameter
2007-01-26 18:10 ` Andrew Morton
2007-01-26 18:21 ` KAMEZAWA Hiroyuki
2007-01-26 18:23 ` Christoph Lameter [this message]
2007-01-26 18:42 ` Andrew Morton
2007-01-27 22:19 ` Rik van Riel
2007-01-27 22:30 ` Andrew Morton
2007-01-27 22:36 ` Rik van Riel
2007-01-26 11:46 ` Nick Piggin
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