From: Mel Gorman <mgorman@suse.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
Ingo Molnar <mingo@kernel.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Linux-MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 15/18] sched: Set preferred NUMA node based on number of private faults
Date: Wed, 31 Jul 2013 11:10:41 +0100 [thread overview]
Message-ID: <20130731101041.GQ2296@suse.de> (raw)
In-Reply-To: <20130731093437.GX3008@twins.programming.kicks-ass.net>
On Wed, Jul 31, 2013 at 11:34:37AM +0200, Peter Zijlstra wrote:
> On Wed, Jul 31, 2013 at 10:29:38AM +0100, Mel Gorman wrote:
> > > Hurmph I just stumbled upon this PMD 'trick' and I'm not at all sure I
> > > like it. If an application would pre-fault/initialize its memory with
> > > the main thread we'll collapse it into a PMDs and forever thereafter (by
> > > virtue of do_pmd_numa_page()) they'll all stay the same. Resulting in
> > > PMD granularity.
> > >
> >
> > Potentially yes. When that PMD trick was introduced it was because the cost
> > of faults was very high due to a high scanning rate. The trick mitigated
> > worse-case scenarios until faults were properly accounted for and the scan
> > rates were better controlled. As these *should* be addressed by the series
> > I think I will be adding a patch to kick away this PMD crutch and see how
> > it looks in profiles.
>
> I've been thinking on this a bit and I think we should split these and
> thp pages when we get shared faults from different nodes on them and
> refuse thp collapses when the pages are on different nodes.
>
Agreed, I reached the same conclusion when thinking about THP false sharing
just before I went on holiday. The first prototype patch was a bit messy
and performed very badly so "Handle false sharing of THP" was chucked onto
the TODO pile to worry about when I got back. It also collided a little with
the PMD handling of base pages which is another reason to get rid of that.
> With the exception that when we introduce the interleave mempolicies we
> should define 'different node' as being outside of the interleave mask.
Understood.
--
Mel Gorman
SUSE Labs
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next prev parent reply other threads:[~2013-07-31 10:10 UTC|newest]
Thread overview: 102+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-15 15:20 [PATCH 0/18] Basic scheduler support for automatic NUMA balancing V5 Mel Gorman
2013-07-15 15:20 ` [PATCH 01/18] mm: numa: Document automatic NUMA balancing sysctls Mel Gorman
2013-07-15 15:20 ` [PATCH 02/18] sched: Track NUMA hinting faults on per-node basis Mel Gorman
2013-07-17 10:50 ` Peter Zijlstra
2013-07-31 7:54 ` Mel Gorman
2013-07-29 10:10 ` Peter Zijlstra
2013-07-31 7:54 ` Mel Gorman
2013-07-15 15:20 ` [PATCH 03/18] mm: numa: Account for THP numa hinting faults on the correct node Mel Gorman
2013-07-17 0:33 ` Hillf Danton
2013-07-17 1:26 ` Wanpeng Li
2013-07-17 1:26 ` Wanpeng Li
2013-07-15 15:20 ` [PATCH 04/18] mm: numa: Do not migrate or account for hinting faults on the zero page Mel Gorman
2013-07-17 11:00 ` Peter Zijlstra
2013-07-31 8:11 ` Mel Gorman
2013-07-15 15:20 ` [PATCH 05/18] sched: Select a preferred node with the most numa hinting faults Mel Gorman
2013-07-15 15:20 ` [PATCH 06/18] sched: Update NUMA hinting faults once per scan Mel Gorman
2013-07-15 15:20 ` [PATCH 07/18] sched: Favour moving tasks towards the preferred node Mel Gorman
2013-07-25 10:40 ` [PATCH] sched, numa: migrates_degrades_locality() Peter Zijlstra
2013-07-31 8:44 ` Mel Gorman
2013-07-31 8:50 ` Peter Zijlstra
2013-07-15 15:20 ` [PATCH 08/18] sched: Reschedule task on preferred NUMA node once selected Mel Gorman
2013-07-17 1:31 ` Hillf Danton
2013-07-31 9:07 ` Mel Gorman
2013-07-31 9:38 ` Srikar Dronamraju
2013-08-01 4:47 ` Srikar Dronamraju
2013-08-01 15:38 ` Mel Gorman
2013-07-15 15:20 ` [PATCH 09/18] sched: Add infrastructure for split shared/private accounting of NUMA hinting faults Mel Gorman
2013-07-17 2:17 ` Hillf Danton
2013-07-31 9:08 ` Mel Gorman
2013-07-15 15:20 ` [PATCH 10/18] sched: Increase NUMA PTE scanning when a new preferred node is selected Mel Gorman
2013-07-15 15:20 ` [PATCH 11/18] sched: Check current->mm before allocating NUMA faults Mel Gorman
2013-07-15 15:20 ` [PATCH 12/18] sched: Set the scan rate proportional to the size of the task being scanned Mel Gorman
2013-07-15 15:20 ` [PATCH 13/18] mm: numa: Scan pages with elevated page_mapcount Mel Gorman
2013-07-17 5:22 ` Sam Ben
2013-07-31 9:13 ` Mel Gorman
2013-07-15 15:20 ` [PATCH 14/18] sched: Remove check that skips small VMAs Mel Gorman
2013-07-15 15:20 ` [PATCH 15/18] sched: Set preferred NUMA node based on number of private faults Mel Gorman
2013-07-18 1:53 ` [PATCH 15/18] fix compilation with !CONFIG_NUMA_BALANCING Rik van Riel
2013-07-31 9:19 ` Mel Gorman
2013-07-26 11:20 ` [PATCH 15/18] sched: Set preferred NUMA node based on number of private faults Peter Zijlstra
2013-07-31 9:29 ` Mel Gorman
2013-07-31 9:34 ` Peter Zijlstra
2013-07-31 10:10 ` Mel Gorman [this message]
2013-07-15 15:20 ` [PATCH 16/18] sched: Avoid overloading CPUs on a preferred NUMA node Mel Gorman
2013-07-15 20:03 ` Peter Zijlstra
2013-07-16 8:23 ` Mel Gorman
2013-07-16 10:35 ` Peter Zijlstra
2013-07-16 15:55 ` Hillf Danton
2013-07-16 16:01 ` Mel Gorman
2013-07-17 10:54 ` Peter Zijlstra
2013-07-31 9:49 ` Mel Gorman
2013-08-01 7:10 ` Srikar Dronamraju
2013-08-01 15:42 ` Mel Gorman
2013-07-15 15:20 ` [PATCH 17/18] sched: Retry migration of tasks to CPU on a preferred node Mel Gorman
2013-07-25 10:33 ` Peter Zijlstra
2013-07-31 10:03 ` Mel Gorman
2013-07-31 10:05 ` Peter Zijlstra
2013-07-31 10:07 ` Mel Gorman
2013-07-25 10:35 ` Peter Zijlstra
2013-08-01 5:13 ` Srikar Dronamraju
2013-08-01 15:46 ` Mel Gorman
2013-07-15 15:20 ` [PATCH 18/18] sched: Swap tasks when reschuling if a CPU on a target node is imbalanced Mel Gorman
2013-07-15 20:11 ` Peter Zijlstra
2013-07-16 9:41 ` Mel Gorman
2013-08-01 4:59 ` Srikar Dronamraju
2013-08-01 15:48 ` Mel Gorman
2013-07-15 20:14 ` [PATCH 0/18] Basic scheduler support for automatic NUMA balancing V5 Peter Zijlstra
2013-07-16 15:10 ` Srikar Dronamraju
2013-07-25 10:36 ` Peter Zijlstra
2013-07-31 10:30 ` Mel Gorman
2013-07-31 10:48 ` Peter Zijlstra
2013-07-31 11:57 ` Mel Gorman
2013-07-31 15:30 ` Peter Zijlstra
2013-07-31 16:11 ` Mel Gorman
2013-07-31 16:39 ` Peter Zijlstra
2013-08-01 15:51 ` Mel Gorman
2013-07-25 10:38 ` [PATCH] mm, numa: Sanitize task_numa_fault() callsites Peter Zijlstra
2013-07-31 11:25 ` Mel Gorman
2013-07-25 10:41 ` [PATCH] sched, numa: Improve scanner Peter Zijlstra
2013-07-25 10:46 ` [PATCH] mm, sched, numa: Create a per-task MPOL_INTERLEAVE policy Peter Zijlstra
2013-07-26 9:55 ` Peter Zijlstra
2013-08-26 16:10 ` Peter Zijlstra
2013-08-26 16:14 ` Peter Zijlstra
2013-07-30 11:24 ` [PATCH] mm, numa: Change page last {nid,pid} into {cpu,pid} Peter Zijlstra
2013-08-01 22:33 ` Rik van Riel
2013-07-30 11:38 ` [PATCH] sched, numa: Use {cpu, pid} to create task groups for shared faults Peter Zijlstra
2013-07-31 15:07 ` Peter Zijlstra
2013-07-31 15:38 ` Peter Zijlstra
2013-07-31 15:45 ` Don Morris
2013-07-31 16:05 ` Peter Zijlstra
2013-08-02 16:47 ` [PATCH -v3] " Peter Zijlstra
2013-08-02 16:50 ` [PATCH] mm, numa: Do not group on RO pages Peter Zijlstra
2013-08-02 19:56 ` Peter Zijlstra
2013-08-05 19:36 ` [PATCH] numa,sched: use group fault statistics in numa placement Rik van Riel
2013-08-09 13:55 ` Don Morris
2013-08-28 16:41 ` [PATCH -v3] sched, numa: Use {cpu, pid} to create task groups for shared faults Peter Zijlstra
2013-08-28 17:10 ` Rik van Riel
2013-08-01 6:23 ` [PATCH,RFC] numa,sched: use group fault statistics in numa placement Rik van Riel
2013-08-01 10:37 ` Peter Zijlstra
2013-08-01 16:35 ` Rik van Riel
2013-08-01 22:36 ` [RFC PATCH -v2] " Rik van Riel
2013-07-30 13:58 ` [PATCH 0/18] Basic scheduler support for automatic NUMA balancing V5 Andrew Theurer
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