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
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
WARNING: multiple messages have this Message-ID (diff)
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
next prev parent reply other threads:[~2012-12-04 18:26 UTC|newest]
Thread overview: 78+ 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 ` Ingo Molnar
2012-11-30 19:58 ` [PATCH 01/10] sched: Add "task flipping" support Ingo Molnar
2012-11-30 19:58 ` 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 ` 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 ` 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 ` Ingo Molnar
2012-11-30 19:58 ` [PATCH 05/10] sched: Introduce directed NUMA convergence Ingo Molnar
2012-11-30 19:58 ` Ingo Molnar
2012-11-30 19:58 ` [PATCH 06/10] sched: Remove statistical NUMA scheduling Ingo Molnar
2012-11-30 19:58 ` Ingo Molnar
2012-11-30 19:58 ` [PATCH 07/10] sched: Track quality and strength of convergence Ingo Molnar
2012-11-30 19:58 ` Ingo Molnar
2012-11-30 19:58 ` [PATCH 08/10] sched: Converge NUMA migrations Ingo Molnar
2012-11-30 19:58 ` 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 ` Ingo Molnar
2012-11-30 19:58 ` [PATCH 10/10] sched: Refine the 'shared tasks' memory interleaving logic Ingo Molnar
2012-11-30 19:58 ` Ingo Molnar
2012-11-30 20:37 ` [PATCH 00/10] Latest numa/core release, v18 Linus Torvalds
2012-11-30 20:37 ` 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 9:49 ` 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 12:26 ` Ingo Molnar
2012-12-01 18:38 ` Linus Torvalds
2012-12-01 18:38 ` Linus Torvalds
2012-12-01 18:41 ` Ingo Molnar
2012-12-01 18:41 ` Ingo Molnar
2012-12-01 18:50 ` Linus Torvalds
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 20:10 ` Ingo Molnar
2012-12-01 20:19 ` Rik van Riel
2012-12-01 20:19 ` Rik van Riel
2012-12-02 15:10 ` Ingo Molnar
2012-12-02 15:10 ` Ingo Molnar
2012-12-03 13:59 ` Mel Gorman
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 20:15 ` Ingo Molnar
2012-12-01 20:33 ` Rik van Riel
2012-12-01 20:33 ` Rik van Riel
2012-12-02 15:12 ` [PATCH 2/2, v2] " Ingo Molnar
2012-12-02 15:12 ` Ingo Molnar
2012-12-02 17:53 ` Rik van Riel
2012-12-02 17:53 ` Rik van Riel
2012-12-04 14:42 ` Michel Lespinasse
2012-12-04 14:42 ` Michel Lespinasse
2012-12-05 2:59 ` Michel Lespinasse
2012-12-05 2:59 ` Michel Lespinasse
2012-12-03 14:17 ` [PATCH 2/2] " Mel Gorman
2012-12-03 14:17 ` Mel Gorman
2012-12-04 14:37 ` Michel Lespinasse
2012-12-04 14:37 ` Michel Lespinasse
2012-12-04 18:17 ` Mel Gorman [this message]
2012-12-04 18:17 ` Mel Gorman
2012-12-01 18:55 ` [RFC PATCH] mm/migration: Remove anon vma locking from try_to_unmap() use Rik van Riel
2012-12-01 18:55 ` 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 16:19 ` Rik van Riel
2012-12-01 17:55 ` Linus Torvalds
2012-12-01 17:55 ` Linus Torvalds
2012-12-01 18:30 ` Ingo Molnar
2012-12-01 18:30 ` Ingo Molnar
2012-12-03 13:41 ` [PATCH 00/10] Latest numa/core release, v18 Mel Gorman
2012-12-03 13:41 ` Mel Gorman
2012-12-04 17:30 ` Thomas Gleixner
2012-12-04 17:30 ` Thomas Gleixner
2012-12-03 10:43 ` Mel Gorman
2012-12-03 10:43 ` Mel Gorman
2012-12-03 11:32 ` Mel Gorman
2012-12-03 11:32 ` Mel Gorman
2012-12-04 22:49 ` Mel Gorman
2012-12-04 22:49 ` Mel Gorman
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20121204143714.GB2797@suse.de \
--to=mgorman@suse.de \
--cc=Lee.Schermerhorn@hp.com \
--cc=a.p.zijlstra@chello.nl \
--cc=aarcange@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=cl@linux.com \
--cc=hannes@cmpxchg.org \
--cc=hughd@google.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mingo@kernel.org \
--cc=pjt@google.com \
--cc=riel@redhat.com \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.org \
--cc=walken@google.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.