From: Peter Zijlstra <peterz@infradead.org>
To: Christoph Lameter <cl@linux.com>
Cc: Hugh Dickins <hughd@google.com>, Theodore Ts'o <tytso@mit.edu>,
Andreas Dilger <adilger@dilger.ca>, linux-mm <linux-mm@kvack.org>,
linux-ext4@vger.kernel.org
Subject: Re: Best way to pin a page in ext4?
Date: Wed, 17 Sep 2014 15:57:19 +0200 [thread overview]
Message-ID: <20140917135719.GK2840@worktop.localdomain> (raw)
In-Reply-To: <alpine.DEB.2.11.1409162230160.12769@gentwo.org>
On Tue, Sep 16, 2014 at 10:31:24PM -0500, Christoph Lameter wrote:
> On Tue, 16 Sep 2014, Hugh Dickins wrote:
>
> > On the page migration issue: it's not quite as straightforward as
> > Christoph suggests. He and I agree completely that mlocked pages
> > should be migratable, but some real-time-minded people disagree:
> > so normal compaction is still forbidden to migrate mlocked pages in
> > the vanilla kernel (though we in Google patch that prohibition out).
> > So pinning by refcount is no worse for compaction than mlocking,
> > in the vanilla kernel.
>
> Note though that compaction is not the only mechanism that uses page
> migration.
Agreed, and not all migration paths check for mlocked iirc. ISTR it is
very much possible for mlocked pages to get migrated in mainline.
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next prev parent reply other threads:[~2014-09-17 13:57 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-15 18:51 Best way to pin a page in ext4? Theodore Ts'o
2014-09-15 20:57 ` Andreas Dilger
2014-09-16 18:07 ` Theodore Ts'o
2014-09-16 18:34 ` Christoph Lameter
2014-09-16 18:56 ` Theodore Ts'o
2014-09-17 0:07 ` Hugh Dickins
2014-09-17 1:25 ` Theodore Ts'o
2014-09-17 3:31 ` Christoph Lameter
2014-09-17 13:57 ` Peter Zijlstra [this message]
2014-09-17 20:37 ` Hugh Dickins
2014-09-17 13:56 ` Peter Zijlstra
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