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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Dave Chinner <david@fromorbit.com>
Cc: Mel Gorman <mgorman@suse.de>, Ingo Molnar <mingo@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux-MM <linux-mm@kvack.org>,
	xfs@oss.sgi.com, ppc-dev <linuxppc-dev@lists.ozlabs.org>
Subject: Re: [PATCH 4/4] mm: numa: Slow PTE scan rate if migration failures occur
Date: Wed, 18 Mar 2015 10:31:28 -0700	[thread overview]
Message-ID: <CA+55aFy-Mw74rAdLMMMUgnsG3ZttMWVNGz7CXZJY7q9fqyRYfg@mail.gmail.com> (raw)
In-Reply-To: <CA+55aFwne-fe_Gg-_GTUo+iOAbbNpLBa264JqSFkH79EULyAqw@mail.gmail.com>

On Wed, Mar 18, 2015 at 9:08 AM, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> So why am I wrong? Why is testing for dirty not the same as testing
> for writable?
>
> I can see a few cases:
>
>  - your load has lots of writable (but not written-to) shared memory

Hmm. I tried to look at the xfsprog sources, and I don't see any
MAP_SHARED activity.  It looks like it's just using pread64/pwrite64,
and the only MAP_SHARED is for the xfsio mmap test thing, not for
xfsrepair.

So I don't see any shared mappings, but I don't know the code-base.

>  - something completely different that I am entirely missing

So I think there's something I'm missing. For non-shared mappings, I
still have the idea that pte_dirty should be the same as pte_write.
And yet, your testing of 3.19 shows that it's a big difference.
There's clearly something I'm completely missing.

                          Linus

  reply	other threads:[~2015-03-18 17:31 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-07 15:20 [RFC PATCH 0/4] Automatic NUMA balancing and PROT_NONE handling followup v2r8 Mel Gorman
2015-03-07 15:20 ` [PATCH 1/4] mm: thp: Return the correct value for change_huge_pmd Mel Gorman
2015-03-07 20:13   ` Linus Torvalds
2015-03-07 20:31   ` Linus Torvalds
2015-03-07 20:56     ` Mel Gorman
2015-03-07 15:20 ` [PATCH 2/4] mm: numa: Remove migrate_ratelimited Mel Gorman
2015-03-07 15:20 ` [PATCH 3/4] mm: numa: Mark huge PTEs young when clearing NUMA hinting faults Mel Gorman
2015-03-07 18:33   ` Linus Torvalds
2015-03-07 18:42     ` Linus Torvalds
2015-03-07 15:20 ` [PATCH 4/4] mm: numa: Slow PTE scan rate if migration failures occur Mel Gorman
2015-03-07 16:36   ` Ingo Molnar
2015-03-07 17:37     ` Mel Gorman
2015-03-08  9:54       ` Ingo Molnar
2015-03-07 19:12     ` Linus Torvalds
2015-03-08 10:02       ` Ingo Molnar
2015-03-08 18:35         ` Linus Torvalds
2015-03-08 18:46           ` Linus Torvalds
2015-03-09 11:29           ` Dave Chinner
2015-03-09 16:52             ` Linus Torvalds
2015-03-09 19:19               ` Dave Chinner
2015-03-10 23:55                 ` Linus Torvalds
2015-03-12 13:10                   ` Mel Gorman
2015-03-12 16:20                     ` Linus Torvalds
2015-03-12 18:49                       ` Mel Gorman
2015-03-17  7:06                         ` Dave Chinner
2015-03-17 16:53                           ` Linus Torvalds
2015-03-17 20:51                             ` Dave Chinner
2015-03-17 21:30                               ` Linus Torvalds
2015-03-17 22:08                                 ` Dave Chinner
2015-03-18 16:08                                   ` Linus Torvalds
2015-03-18 17:31                                     ` Linus Torvalds [this message]
2015-03-18 22:23                                       ` Dave Chinner
2015-03-19 14:10                                       ` Mel Gorman
2015-03-19 18:09                                         ` Linus Torvalds
2015-03-19 21:41                                       ` Linus Torvalds
2015-03-19 22:41                                         ` Dave Chinner
2015-03-19 23:05                                           ` Linus Torvalds
2015-03-19 23:23                                             ` Dave Chinner
2015-03-20  0:23                                             ` Dave Chinner
2015-03-20  1:29                                               ` Linus Torvalds
2015-03-20  4:13                                                 ` Dave Chinner
2015-03-20 17:02                                                   ` Linus Torvalds
2015-03-23 12:01                                                     ` Mel Gorman
2015-03-20 10:12                                                 ` Mel Gorman
2015-03-20  9:56                                             ` Mel Gorman
2015-03-08 20:40         ` Mel Gorman
2015-03-09 21:02           ` Mel Gorman
2015-03-10 13:08             ` Mel Gorman
2015-03-08  9:41   ` Ingo Molnar

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