From: Mel Gorman <mgorman@suse.de>
To: Ingo Molnar <mingo@kernel.org>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Paul Turner <pjt@google.com>,
Lee Schermerhorn <Lee.Schermerhorn@hp.com>,
Christoph Lameter <cl@linux.com>, Rik van Riel <riel@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
Johannes Weiner <hannes@cmpxchg.org>,
Hugh Dickins <hughd@google.com>, Alex Shi <lkml.alex@gmail.com>,
Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Subject: Re: [PATCH 18/52] mm/numa: Migrate on reference policy
Date: Mon, 3 Dec 2012 15:44:58 +0000 [thread overview]
Message-ID: <20121203154458.GO8218@suse.de> (raw)
In-Reply-To: <1354473824-19229-19-git-send-email-mingo@kernel.org>
On Sun, Dec 02, 2012 at 07:43:10PM +0100, Ingo Molnar wrote:
> From: Mel Gorman <mgorman@suse.de>
>
> This is the simplest possible policy that still does something
> of note. When a pte_numa is faulted, it is moved immediately.
> Any replacement policy must at least do better than this and in
> all likelihood this policy regresses normal workloads.
>
> Signed-off-by: Mel Gorman <mgorman@suse.de>
> Acked-by: Rik van Riel <riel@redhat.com>
> Cc: Johannes Weiner <hannes@cmpxchg.org>
> Cc: Hugh Dickins <hughd@google.com>
> Cc: Paul Turner <pjt@google.com>
> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
> Cc: Alex Shi <lkml.alex@gmail.com>
> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
> Cc: Linus Torvalds <torvalds@linux-foundation.org>
> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Cc: Andrea Arcangeli <aarcange@redhat.com>
> Signed-off-by: Ingo Molnar <mingo@kernel.org>
It is worth noting that at this point in your combined tree that this
policy and patch does not and cannot do anything. It has none of the
faulting machinery, pte scanning, two-stage filter etc that are necessary
for it to work. So for example, you can not take this point of your tree,
compare it with balancenuma and get a meaningful comparison.
So while superfically this patch looks like a useful bisection point, it
isn't. A plain rebase on top of balancenuma would have given us a comparison
between "do nothing", "do the bare minimum to be useful (balancenuma)" and
"do something complex (numacore)" even *if* you decided to revert parts
of balancenuma during your rebase. For example, you might have decided
to force the removal of migrate rate-limiting even though I stand by it
being a valid decision to mitigate worst-case behaviour. The key is that
it would have been possible to bisect parts of numacore to help identify
the source of any regressions.
This restructure is an all or nothing approach. It does not look like it's
possible to do a comparison between "do nothing", "do the bare minimum
(balancenuma)" and "do something complex (numacore)". It would also be
impossible to do any sort of rebase of autonuma policies on top as was
the case with balancenuma.
FWIW, I pulled tip again this morning and rebased tip/numa/base to
3.7-rc7 and queued the result. I had pulled tip/master but it didn't
boot.
--
Mel Gorman
SUSE Labs
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next prev parent reply other threads:[~2012-12-03 15:45 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-02 18:42 [PATCH 00/52] RFC: Unified NUMA balancing tree, v1 Ingo Molnar
2012-12-02 18:42 ` [PATCH 01/52] mm/compaction: Move migration fail/success stats to migrate.c Ingo Molnar
2012-12-02 18:42 ` [PATCH 02/52] mm/compaction: Add scanned and isolated counters for compaction Ingo Molnar
2012-12-02 18:42 ` [PATCH 03/52] mm/migrate: Add a tracepoint for migrate_pages Ingo Molnar
2012-12-02 18:42 ` [PATCH 04/52] mm/numa: define _PAGE_NUMA Ingo Molnar
2012-12-02 18:42 ` [PATCH 05/52] mm/numa: Add pte_numa() and pmd_numa() Ingo Molnar
2012-12-02 18:42 ` [PATCH 06/52] mm/numa: Support NUMA hinting page faults from gup/gup_fast Ingo Molnar
2012-12-02 18:42 ` [PATCH 07/52] mm/numa: split_huge_page: transfer the NUMA type from the pmd to the pte Ingo Molnar
2012-12-02 18:43 ` [PATCH 08/52] mm/numa: Create basic numa page hinting infrastructure Ingo Molnar
2012-12-02 18:43 ` [PATCH 09/52] mm/mempolicy: Make MPOL_LOCAL a real policy Ingo Molnar
2012-12-02 18:43 ` [PATCH 10/52] mm/mempolicy: Add MPOL_MF_NOOP Ingo Molnar
2012-12-02 18:43 ` [PATCH 11/52] mm/mempolicy: Check for misplaced page Ingo Molnar
2012-12-02 18:43 ` [PATCH 12/52] mm/migrate: Introduce migrate_misplaced_page() Ingo Molnar
2012-12-02 18:43 ` [PATCH 13/52] mm/mempolicy: Use _PAGE_NUMA to migrate pages Ingo Molnar
2012-12-02 18:43 ` [PATCH 14/52] mm/mempolicy: Add MPOL_MF_LAZY Ingo Molnar
2012-12-02 18:43 ` [PATCH 15/52] mm/mempolicy: Implement change_prot_numa() in terms of change_protection() Ingo Molnar
2012-12-02 18:43 ` [PATCH 16/52] mm/mempolicy: Hide MPOL_NOOP and MPOL_MF_LAZY from userspace for now Ingo Molnar
2012-12-02 18:43 ` [PATCH 17/52] mm/numa: Add pte updates, hinting and migration stats Ingo Molnar
2012-12-02 18:43 ` [PATCH 18/52] mm/numa: Migrate on reference policy Ingo Molnar
2012-12-03 15:44 ` Mel Gorman [this message]
2012-12-02 18:43 ` [PATCH 19/52] sched, numa, mm: Add last_cpu to page flags Ingo Molnar
2012-12-02 18:43 ` [PATCH 20/52] mm, numa: Implement migrate-on-fault lazy NUMA strategy for regular and THP pages Ingo Molnar
2012-12-05 0:55 ` David Rientjes
2012-12-05 9:43 ` Mel Gorman
2012-12-02 18:43 ` [PATCH 21/52] sched: Make find_busiest_queue() a method Ingo Molnar
2012-12-02 18:43 ` [PATCH 22/52] sched, numa, mm: Add credits for NUMA placement Ingo Molnar
2012-12-02 18:43 ` [PATCH 23/52] sched, numa, mm: Describe the NUMA scheduling problem formally Ingo Molnar
2012-12-02 18:43 ` [PATCH 24/52] sched: Add adaptive NUMA affinity support Ingo Molnar
2012-12-02 18:43 ` [PATCH 25/52] sched, numa: Improve the CONFIG_NUMA_BALANCING help text Ingo Molnar
2012-12-02 18:43 ` [PATCH 26/52] sched: Implement constant, per task Working Set Sampling (WSS) rate Ingo Molnar
2012-12-02 18:43 ` [PATCH 27/52] sched, numa, mm: Count WS scanning against present PTEs, not virtual memory ranges Ingo Molnar
2012-12-02 18:43 ` [PATCH 28/52] sched: Implement slow start for working set sampling Ingo Molnar
2012-12-02 18:43 ` [PATCH 29/52] sched: Implement NUMA scanning backoff Ingo Molnar
2012-12-03 19:55 ` Rik van Riel
2012-12-02 18:43 ` [PATCH 30/52] sched: Improve convergence Ingo Molnar
2012-12-02 18:43 ` [PATCH 31/52] sched: Introduce staged average NUMA faults Ingo Molnar
2012-12-02 18:43 ` [PATCH 32/52] sched: Track groups of shared tasks Ingo Molnar
2012-12-03 22:46 ` Rik van Riel
2012-12-02 18:43 ` [PATCH 33/52] sched: Use the best-buddy 'ideal cpu' in balancing decisions Ingo Molnar
2012-12-02 18:43 ` [PATCH 34/52] sched: Average the fault stats longer Ingo Molnar
2012-12-02 18:43 ` [PATCH 35/52] sched: Use the ideal CPU to drive active balancing Ingo Molnar
2012-12-02 18:43 ` [PATCH 36/52] sched: Add hysteresis to p->numa_shared Ingo Molnar
2012-12-02 18:43 ` [PATCH 37/52] sched, numa, mm: Interleave shared tasks Ingo Molnar
2012-12-02 18:43 ` [PATCH 38/52] sched, mm, mempolicy: Add per task mempolicy Ingo Molnar
2012-12-02 18:43 ` [PATCH 39/52] sched: Track shared task's node groups and interleave their memory allocations Ingo Molnar
2012-12-02 18:43 ` [PATCH 40/52] sched: Add "task flipping" support Ingo Molnar
2012-12-02 18:43 ` [PATCH 41/52] sched: Move the NUMA placement logic to a worklet Ingo Molnar
2012-12-02 18:43 ` [PATCH 42/52] numa, mempolicy: Improve CONFIG_NUMA_BALANCING=y OOM behavior Ingo Molnar
2012-12-02 18:43 ` [PATCH 43/52] sched: Introduce directed NUMA convergence Ingo Molnar
2012-12-02 18:43 ` [PATCH 44/52] sched: Remove statistical NUMA scheduling Ingo Molnar
2012-12-02 18:43 ` [PATCH 45/52] sched: Track quality and strength of convergence Ingo Molnar
2012-12-02 18:43 ` [PATCH 46/52] sched: Converge NUMA migrations Ingo Molnar
2012-12-02 18:43 ` [PATCH 47/52] sched: Add convergence strength based adaptive NUMA page fault rate Ingo Molnar
2012-12-02 18:43 ` [PATCH 48/52] sched: Refine the 'shared tasks' memory interleaving logic Ingo Molnar
2012-12-02 18:43 ` [PATCH 49/52] mm/rmap: Convert the struct anon_vma::mutex to an rwsem Ingo Molnar
2012-12-04 14:43 ` Michel Lespinasse
2012-12-02 18:43 ` [PATCH 50/52] mm/rmap, migration: Make rmap_walk_anon() and try_to_unmap_anon() more scalable Ingo Molnar
2012-12-02 18:43 ` [PATCH 51/52] sched: Exclude pinned tasks from the NUMA-balancing logic Ingo Molnar
2012-12-02 18:43 ` [PATCH 52/52] sched: Add RSS filter to NUMA-balancing Ingo Molnar
2012-12-03 5:09 ` [PATCH 00/52] RFC: Unified NUMA balancing tree, v1 Ingo Molnar
2012-12-03 9:25 ` [GIT] Unified NUMA balancing tree, v2 Ingo Molnar
2012-12-03 15:52 ` [PATCH 00/52] RFC: Unified NUMA balancing tree, v1 Rik van Riel
2012-12-03 17:11 ` Ingo Molnar
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