From: Mel Gorman <mgorman@suse.de>
To: Michel Lespinasse <walken@google.com>
Cc: Ingo Molnar <mingo@kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-mm <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>,
Thomas Gleixner <tglx@linutronix.de>,
Johannes Weiner <hannes@cmpxchg.org>,
Hugh Dickins <hughd@google.com>
Subject: Re: [PATCH 2/2] mm/migration: Make rmap_walk_anon() and try_to_unmap_anon() more scalable
Date: Tue, 4 Dec 2012 18:17:56 +0000 [thread overview]
Message-ID: <20121204143714.GB2797@suse.de> (raw)
In-Reply-To: <CANN689Hm=g+PhJrVZ8mngPL58k45GfmwL_19F27WtwJC0G-=6g@mail.gmail.com>
On Tue, Dec 04, 2012 at 06:37:41AM -0800, Michel Lespinasse wrote:
> On Mon, Dec 3, 2012 at 6:17 AM, Mel Gorman <mgorman@suse.de> wrote:
> > On Sat, Dec 01, 2012 at 09:15:38PM +0100, Ingo Molnar wrote:
> >> @@ -732,7 +732,7 @@ static int page_referenced_anon(struct p
> >> struct anon_vma_chain *avc;
> >> int referenced = 0;
> >>
> >> - anon_vma = page_lock_anon_vma(page);
> >> + anon_vma = page_lock_anon_vma_read(page);
> >> if (!anon_vma)
> >> return referenced;
> >
> > This is a slightly trickier one as this path is called from reclaim. It does
> > open the possibility that reclaim can stall something like a parallel fork
> > or anything that requires the anon_vma rwsem for a period of time. I very
> > severely doubt it'll really be a problem but keep an eye out for bug reports
> > related to delayed mmap/fork/anything_needing_write_lock during page reclaim.
>
> I don't see why this would be a problem - rwsem does implement
> reader/writer fairness, so having some sites do a read lock instead of
> a write lock shouldn't cause the write lock sites to starve. Is this
> what you were worried about ?
>
Yes. I did not expect they would be starved forever, just delayed longer
than they might have been before. I would be very surprised if there is
anything other than a synthetic case that will really care but I've been
"very surprised" before :)
--
Mel Gorman
SUSE Labs
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next prev parent reply other threads:[~2012-12-04 18:26 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-30 19:58 [PATCH 00/10] Latest numa/core release, v18 Ingo Molnar
2012-11-30 19:58 ` [PATCH 01/10] sched: Add "task flipping" support Ingo Molnar
2012-11-30 19:58 ` [PATCH 02/10] sched: Move the NUMA placement logic to a worklet Ingo Molnar
2012-11-30 19:58 ` [PATCH 03/10] numa, mempolicy: Improve CONFIG_NUMA_BALANCING=y OOM behavior Ingo Molnar
2012-11-30 19:58 ` [PATCH 04/10] mm, numa: Turn 4K pte NUMA faults into effective hugepage ones Ingo Molnar
2012-11-30 19:58 ` [PATCH 05/10] sched: Introduce directed NUMA convergence Ingo Molnar
2012-11-30 19:58 ` [PATCH 06/10] sched: Remove statistical NUMA scheduling Ingo Molnar
2012-11-30 19:58 ` [PATCH 07/10] sched: Track quality and strength of convergence Ingo Molnar
2012-11-30 19:58 ` [PATCH 08/10] sched: Converge NUMA migrations Ingo Molnar
2012-11-30 19:58 ` [PATCH 09/10] sched: Add convergence strength based adaptive NUMA page fault rate Ingo Molnar
2012-11-30 19:58 ` [PATCH 10/10] sched: Refine the 'shared tasks' memory interleaving logic Ingo Molnar
2012-11-30 20:37 ` [PATCH 00/10] Latest numa/core release, v18 Linus Torvalds
2012-12-01 9:49 ` [RFC PATCH] mm/migration: Don't lock anon vmas in rmap_walk_anon() Ingo Molnar
2012-12-01 12:26 ` [RFC PATCH] mm/migration: Remove anon vma locking from try_to_unmap() use Ingo Molnar
2012-12-01 18:38 ` Linus Torvalds
2012-12-01 18:41 ` Ingo Molnar
2012-12-01 18:50 ` Linus Torvalds
2012-12-01 20:10 ` [PATCH 1/2] mm/rmap: Convert the struct anon_vma::mutex to an rwsem Ingo Molnar
2012-12-01 20:19 ` Rik van Riel
2012-12-02 15:10 ` Ingo Molnar
2012-12-03 13:59 ` Mel Gorman
2012-12-01 20:15 ` [PATCH 2/2] mm/migration: Make rmap_walk_anon() and try_to_unmap_anon() more scalable Ingo Molnar
2012-12-01 20:33 ` Rik van Riel
2012-12-02 15:12 ` [PATCH 2/2, v2] " Ingo Molnar
2012-12-02 17:53 ` Rik van Riel
2012-12-04 14:42 ` Michel Lespinasse
2012-12-05 2:59 ` Michel Lespinasse
2012-12-03 14:17 ` [PATCH 2/2] " Mel Gorman
2012-12-04 14:37 ` Michel Lespinasse
2012-12-04 18:17 ` Mel Gorman [this message]
2012-12-01 18:55 ` [RFC PATCH] mm/migration: Remove anon vma locking from try_to_unmap() use Rik van Riel
2012-12-01 16:19 ` [RFC PATCH] mm/migration: Don't lock anon vmas in rmap_walk_anon() Rik van Riel
2012-12-01 17:55 ` Linus Torvalds
2012-12-01 18:30 ` Ingo Molnar
2012-12-03 13:41 ` [PATCH 00/10] Latest numa/core release, v18 Mel Gorman
2012-12-04 17:30 ` Thomas Gleixner
2012-12-03 10:43 ` Mel Gorman
2012-12-03 11:32 ` Mel Gorman
2012-12-04 22:49 ` Mel Gorman
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