From: Mel Gorman <mgorman@suse.de>
To: Rik van Riel <riel@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
Andrea Arcangeli <aarcange@redhat.com>,
Ingo Molnar <mingo@kernel.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Hugh Dickins <hughd@google.com>,
Thomas Gleixner <tglx@linutronix.de>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Linux-MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 08/19] mm: numa: Create basic numa page hinting infrastructure
Date: Wed, 7 Nov 2012 11:00:09 +0000 [thread overview]
Message-ID: <20121107110008.GW8218@suse.de> (raw)
In-Reply-To: <509A3C7E.9040809@redhat.com>
On Wed, Nov 07, 2012 at 05:48:30AM -0500, Rik van Riel wrote:
> On 11/07/2012 05:38 AM, Mel Gorman wrote:
> >On Tue, Nov 06, 2012 at 01:58:26PM -0500, Rik van Riel wrote:
> >>On 11/06/2012 04:14 AM, Mel Gorman wrote:
> >>>Note: This patch started as "mm/mpol: Create special PROT_NONE
> >>> infrastructure" and preserves the basic idea but steals *very*
> >>> heavily from "autonuma: numa hinting page faults entry points" for
> >>> the actual fault handlers without the migration parts. The end
> >>> result is barely recognisable as either patch so all Signed-off
> >>> and Reviewed-bys are dropped. If Peter, Ingo and Andrea are ok with
> >>> this version, I will re-add the signed-offs-by to reflect the history.
> >>>
> >>>In order to facilitate a lazy -- fault driven -- migration of pages, create
> >>>a special transient PAGE_NUMA variant, we can then use the 'spurious'
> >>>protection faults to drive our migrations from.
> >>>
> >>>Pages that already had an effective PROT_NONE mapping will not be detected
> >>
> >>The patch itself is good, but the changelog needs a little
> >>fix. While you are defining _PAGE_NUMA to _PAGE_PROTNONE on
> >>x86, this may be different on other architectures.
> >>
> >>Therefore, the changelog should refer to PAGE_NUMA, not
> >>PROT_NONE.
> >>
> >
> >Fair point. I still want to record the point that PROT_NONE will not
> >generate the faults though. How about this?
> >
> > In order to facilitate a lazy -- fault driven -- migration of pages, create
> > a special transient PAGE_NUMA variant, we can then use the 'spurious'
> > protection faults to drive our migrations from.
> >
> > The meaning of PAGE_NUMA depends on the architecture but on x86 it is
> > effectively PROT_NONE. In this case, PROT_NONE mappings will not be detected
> > to generate these 'spurious' faults for the simple reason that we cannot
> > distinguish them on their protection bits, see pte_numa(). This isn't
> > a problem since PROT_NONE (and possible PROT_WRITE with dirty tracking)
> > aren't used or are rare enough for us to not care about their placement.
>
> Actual PROT_NONE mappings will not generate these NUMA faults
> for the reason that the page fault code checks the permission
> on the VMA (and will throw a segmentation fault on actual
> PROT_NONE mappings), before it ever calls handle_mm_fault.
>
Updated. Thanks.
--
Mel Gorman
SUSE Labs
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next prev parent reply other threads:[~2012-11-07 11:00 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-06 9:14 [RFC PATCH 00/19] Foundation for automatic NUMA balancing Mel Gorman
2012-11-06 9:14 ` [PATCH 01/19] mm: compaction: Move migration fail/success stats to migrate.c Mel Gorman
2012-11-06 17:32 ` Rik van Riel
2012-11-06 9:14 ` [PATCH 02/19] mm: migrate: Add a tracepoint for migrate_pages Mel Gorman
2012-11-06 17:33 ` Rik van Riel
2012-11-06 9:14 ` [PATCH 03/19] mm: compaction: Add scanned and isolated counters for compaction Mel Gorman
2012-11-06 17:35 ` Rik van Riel
2012-11-06 9:14 ` [PATCH 04/19] mm: numa: define _PAGE_NUMA Mel Gorman
2012-11-06 18:35 ` Rik van Riel
2012-11-06 9:14 ` [PATCH 05/19] mm: numa: pte_numa() and pmd_numa() Mel Gorman
2012-11-13 9:54 ` Ingo Molnar
2012-11-13 11:24 ` Mel Gorman
2012-11-06 9:14 ` [PATCH 06/19] mm: numa: teach gup_fast about pmd_numa Mel Gorman
2012-11-13 10:07 ` Ingo Molnar
2012-11-13 11:37 ` Mel Gorman
2012-11-13 13:51 ` Ingo Molnar
2012-11-06 9:14 ` [PATCH 07/19] mm: numa: split_huge_page: transfer the NUMA type from the pmd to the pte Mel Gorman
2012-11-06 9:14 ` [PATCH 08/19] mm: numa: Create basic numa page hinting infrastructure Mel Gorman
2012-11-06 18:58 ` Rik van Riel
2012-11-07 10:38 ` Mel Gorman
2012-11-07 10:48 ` Rik van Riel
2012-11-07 11:00 ` Mel Gorman [this message]
2012-11-13 10:21 ` Ingo Molnar
2012-11-13 11:50 ` Mel Gorman
2012-11-13 13:49 ` Ingo Molnar
2012-11-13 14:26 ` Mel Gorman
2012-11-06 9:14 ` [PATCH 09/19] mm: mempolicy: Make MPOL_LOCAL a real policy Mel Gorman
2012-11-06 9:14 ` [PATCH 10/19] mm: mempolicy: Add MPOL_MF_NOOP Mel Gorman
2012-11-06 9:14 ` [PATCH 11/19] mm: mempolicy: Check for misplaced page Mel Gorman
2012-11-06 9:14 ` [PATCH 12/19] mm: migrate: Introduce migrate_misplaced_page() Mel Gorman
2012-11-06 19:10 ` Rik van Riel
2012-11-13 9:36 ` Ingo Molnar
2012-11-13 11:43 ` Ingo Molnar
2012-11-13 11:56 ` Mel Gorman
2012-11-13 14:49 ` Rik van Riel
2012-11-06 9:14 ` [PATCH 13/19] mm: mempolicy: Use _PAGE_NUMA to migrate pages Mel Gorman
2012-11-06 19:18 ` Rik van Riel
2012-11-07 12:32 ` Mel Gorman
2012-11-06 9:14 ` [PATCH 14/19] mm: mempolicy: Add MPOL_MF_LAZY Mel Gorman
2012-11-06 19:19 ` Rik van Riel
2012-11-13 10:25 ` Ingo Molnar
2012-11-13 12:02 ` Mel Gorman
2012-11-06 9:14 ` [PATCH 15/19] mm: numa: Add fault driven placement and migration Mel Gorman
2012-11-06 19:41 ` Rik van Riel
2012-11-07 10:49 ` Mel Gorman
2012-11-07 11:46 ` Rik van Riel
2012-11-13 10:45 ` Ingo Molnar
2012-11-13 12:09 ` Mel Gorman
2012-11-13 13:39 ` Ingo Molnar
2012-11-06 9:14 ` [PATCH 16/19] mm: numa: Add pte updates, hinting and migration stats Mel Gorman
2012-11-06 19:55 ` Rik van Riel
2012-11-07 10:57 ` Mel Gorman
2012-11-07 11:47 ` Rik van Riel
2012-11-06 9:14 ` [PATCH 17/19] mm: numa: Migrate on reference policy Mel Gorman
2012-11-07 11:56 ` Rik van Riel
2012-11-06 9:14 ` [PATCH 18/19] mm: sched: numa: Implement constant, per task Working Set Sampling (WSS) rate Mel Gorman
2012-11-06 19:55 ` Rik van Riel
2012-11-06 9:14 ` [PATCH 19/19] mm: sched: numa: Implement slow start for working set sampling Mel Gorman
2012-11-06 19:56 ` Rik van Riel
2012-11-07 9:27 ` [RFC PATCH 00/19] Foundation for automatic NUMA balancing Zhouping Liu
2012-11-07 15:25 ` Mel Gorman
2012-11-08 6:37 ` Zhouping Liu
2012-11-08 6:39 ` 杨竹
2012-11-08 7:03 ` Zhouping Liu
2012-11-09 14:42 ` Andrea Arcangeli
2012-11-09 16:12 ` Mel Gorman
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