From: Nick Piggin <npiggin@kernel.dk>
To: Michel Lespinasse <walken@google.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Hugh Dickins <hughd@google.com>, Rik van Riel <riel@redhat.com>,
Kosaki Motohiro <kosaki.motohiro@jp.fujitsu.com>,
Peter Zijlstra <peterz@infradead.org>,
Nick Piggin <npiggin@kernel.dk>, Theodore Tso <tytso@google.com>,
Michael Rubin <mrubin@google.com>,
Suleiman Souhlal <suleiman@google.com>
Subject: Re: [PATCH 3/3] mlock: avoid dirtying pages and triggering writeback
Date: Wed, 17 Nov 2010 23:57:56 +1100 [thread overview]
Message-ID: <20101117125756.GA5576@amd> (raw)
In-Reply-To: <1289996638-21439-4-git-send-email-walken@google.com>
On Wed, Nov 17, 2010 at 04:23:58AM -0800, Michel Lespinasse wrote:
> When faulting in pages for mlock(), we want to break COW for anonymous
> or file pages within VM_WRITABLE, non-VM_SHARED vmas. However, there is
> no need to write-fault into VM_SHARED vmas since shared file pages can
> be mlocked first and dirtied later, when/if they actually get written to.
> Skipping the write fault is desirable, as we don't want to unnecessarily
> cause these pages to be dirtied and queued for writeback.
It's not just to break COW, but to do block allocation and such
(filesystem's page_mkwrite op). That needs to at least be explained
in the changelog.
Filesystem doesn't have a good way to fully pin required things
according to mlock, but page_mkwrite provides some reasonable things
(like block allocation / reservation).
WARNING: multiple messages have this Message-ID (diff)
From: Nick Piggin <npiggin@kernel.dk>
To: Michel Lespinasse <walken@google.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Hugh Dickins <hughd@google.com>, Rik van Riel <riel@redhat.com>,
Kosaki Motohiro <kosaki.motohiro@jp.fujitsu.com>,
Peter Zijlstra <peterz@infradead.org>,
Nick Piggin <npiggin@kernel.dk>, Theodore Tso <tytso@google.com>,
Michael Rubin <mrubin@google.com>,
Suleiman Souhlal <suleiman@google.com>
Subject: Re: [PATCH 3/3] mlock: avoid dirtying pages and triggering writeback
Date: Wed, 17 Nov 2010 23:57:56 +1100 [thread overview]
Message-ID: <20101117125756.GA5576@amd> (raw)
In-Reply-To: <1289996638-21439-4-git-send-email-walken@google.com>
On Wed, Nov 17, 2010 at 04:23:58AM -0800, Michel Lespinasse wrote:
> When faulting in pages for mlock(), we want to break COW for anonymous
> or file pages within VM_WRITABLE, non-VM_SHARED vmas. However, there is
> no need to write-fault into VM_SHARED vmas since shared file pages can
> be mlocked first and dirtied later, when/if they actually get written to.
> Skipping the write fault is desirable, as we don't want to unnecessarily
> cause these pages to be dirtied and queued for writeback.
It's not just to break COW, but to do block allocation and such
(filesystem's page_mkwrite op). That needs to at least be explained
in the changelog.
Filesystem doesn't have a good way to fully pin required things
according to mlock, but page_mkwrite provides some reasonable things
(like block allocation / reservation).
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next prev parent reply other threads:[~2010-11-17 12:58 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-17 12:23 [PATCH 0/3] Avoid dirtying pages during mlock Michel Lespinasse
2010-11-17 12:23 ` Michel Lespinasse
2010-11-17 12:23 ` [PATCH 1/3] do_wp_page: remove the 'reuse' flag Michel Lespinasse
2010-11-17 12:23 ` Michel Lespinasse
2010-11-17 12:23 ` [PATCH 2/3] do_wp_page: clarify dirty_page handling Michel Lespinasse
2010-11-17 12:23 ` Michel Lespinasse
2010-11-17 12:23 ` [PATCH 3/3] mlock: avoid dirtying pages and triggering writeback Michel Lespinasse
2010-11-17 12:23 ` Michel Lespinasse
2010-11-17 12:57 ` Nick Piggin [this message]
2010-11-17 12:57 ` Nick Piggin
2010-11-17 15:28 ` Peter Zijlstra
2010-11-17 15:28 ` Peter Zijlstra
2010-11-17 22:05 ` Michel Lespinasse
2010-11-17 22:05 ` Michel Lespinasse
2010-11-17 22:18 ` Peter Zijlstra
2010-11-17 22:18 ` Peter Zijlstra
2010-11-17 23:11 ` Dave Chinner
2010-11-17 23:11 ` Dave Chinner
2010-11-17 23:31 ` Michel Lespinasse
2010-11-17 23:31 ` Michel Lespinasse
2010-11-19 1:46 ` Dave Chinner
2010-11-19 1:46 ` Dave Chinner
2010-11-17 23:52 ` Ted Ts'o
2010-11-17 23:52 ` Ted Ts'o
2010-11-18 0:53 ` Andrew Morton
2010-11-18 0:53 ` Andrew Morton
2010-11-18 11:03 ` Michel Lespinasse
2010-11-18 11:03 ` Michel Lespinasse
2010-11-18 13:37 ` Christoph Hellwig
2010-11-18 13:37 ` Christoph Hellwig
2010-11-18 17:41 ` Hugh Dickins
2010-11-18 17:41 ` Hugh Dickins
2010-11-19 7:23 ` Michel Lespinasse
2010-11-19 7:23 ` Michel Lespinasse
2010-11-19 13:38 ` Theodore Tso
2010-11-19 13:42 ` Theodore Tso
2010-11-19 13:42 ` Theodore Tso
2010-11-19 15:06 ` Christoph Hellwig
2010-11-19 15:06 ` Christoph Hellwig
2010-11-19 22:54 ` Andrew Morton
2010-11-19 22:54 ` Andrew Morton
2010-11-19 23:22 ` Ted Ts'o
2010-11-19 23:22 ` Ted Ts'o
2010-11-20 0:29 ` Dustin Kirkland
2010-11-19 23:31 ` Michel Lespinasse
2010-11-19 23:31 ` Michel Lespinasse
2010-11-19 23:54 ` Dave Chinner
2010-11-19 23:54 ` Dave Chinner
2010-11-18 5:46 ` Nick Piggin
2010-11-18 5:46 ` Nick Piggin
2010-11-18 10:43 ` Theodore Tso
2010-11-18 10:43 ` Theodore Tso
2010-11-18 13:39 ` Christoph Hellwig
2010-11-18 13:39 ` Christoph Hellwig
2010-11-18 18:00 ` Hugh Dickins
2010-11-18 18:00 ` Hugh Dickins
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