From: Linus Torvalds <torvalds@linux-foundation.org>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Bron Gondwana <brong@fastmail.fm>,
Christian Kujau <lists@nerdbynature.de>,
Andrew Morton <akpm@linux-foundation.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
robm@fastmail.fm
Subject: Re: mmap dirty limits on 32 bit kernels (Was: [BUG] New Kernel Bugs)
Date: Thu, 15 Nov 2007 13:26:13 -0800 (PST) [thread overview]
Message-ID: <alpine.LFD.0.9999.0711151320010.4260@woody.linux-foundation.org> (raw)
In-Reply-To: <alpine.LFD.0.9999.0711151300250.4260@woody.linux-foundation.org>
On Thu, 15 Nov 2007, Linus Torvalds wrote:
>
> The problem with HIGHMEM is that it causes various metadata (dentries,
> inodes, page struct tables etc) to eat up memory "prime real estate" under
> the same kind of conditions that also dirty a lot of memory. So the reason
> we disallow HIGHMEM from dirty limits is only *partly* the per-device or
> mapping DMA limits, and to a large degree the fact that non-highmem memory
> is special in general, and it is usually the non-highmem areas that are
> constrained - and need to be protected.
Final note on this (promise):
I'd really be very interested to hear if the patch I *do* think makes
sense (ie the removal of the old "unmapped_ratio" logic) actually already
solves most of Bron's problems.
It may well be that that unmapped_ratio logic effectively undid the system
configuration changes that Bron has done. It doesn't matter if Bron has
>From our sysctl.conf:
# This should help reduce flushing on Cache::FastMmap files
vm.dirty_background_ratio = 50
vm.dirty_expire_centisecs = 9000
vm.dirty_ratio = 80
vm.dirty_writeback_centisecs = 3000
if it turns out that the "unmapped_ratio" logic turns the 80% back down to
5%.
It may well be that 80% of the non-highmem memory is plenty good enough!
Sure, older kernels allowed even more of memory to be dirty (since they
didn't count dirty mappings at all), but we may have a case where the fact
that we discount the HIGHMEM stuff isn't the major problem in itself, and
that the dirty_ratio sysctl should be ok - but just gets screwed over by
that unmapped_ratio logic.
So Bron, if you can test that patch, I'd love to hear if it matters. It
may not make any difference (maybe you don't actually trigger the
unmapped_ratio logic at all), but I think it has the potential for being
totally broken for you.
People that don't change the dirty_ratio from the default values would
generally never care, because the default dirty-ratio is *already* so low
that even if the unmapped_ratio logic triggers, it won't much matter!
Linus
next prev parent reply other threads:[~2007-11-15 21:26 UTC|newest]
Thread overview: 268+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-11-13 6:42 [BUG] New Kernel Bugs Natalie Protasevich
2007-11-13 11:15 ` Andrew Morton
2007-11-13 11:24 ` Jens Axboe
2007-11-13 11:33 ` Evgeniy Polyakov
2007-11-13 11:39 ` David Miller
2007-11-13 11:49 ` Andrew Morton
2007-11-13 11:58 ` David Miller
2007-11-13 12:12 ` Andrew Morton
2007-11-13 12:32 ` David Miller
2007-11-13 19:02 ` Andrew Morton
2007-11-13 20:00 ` Christian Kujau
2007-11-13 21:04 ` Andrew Morton
2007-11-13 16:56 ` Nick Piggin
2007-11-14 19:54 ` Linus Torvalds
2007-11-14 22:22 ` Heikki Orsila
2007-11-14 23:05 ` Linus Torvalds
2007-11-13 21:37 ` Adrian Bunk
2007-11-13 21:56 ` Christian Kujau
2007-11-15 4:07 ` Bron Gondwana
2007-11-15 4:24 ` Linus Torvalds
2007-11-15 5:25 ` Bron Gondwana
2007-11-15 5:35 ` Linus Torvalds
2007-11-15 5:53 ` Linus Torvalds
2007-11-15 11:50 ` mmap dirty limits on 32 bit kernels (Was: [BUG] New Kernel Bugs) Bron Gondwana
2007-11-15 16:32 ` Linus Torvalds
2007-11-15 19:40 ` Peter Zijlstra
2007-11-15 20:44 ` Peter Zijlstra
2007-11-15 20:56 ` Linus Torvalds
2007-11-15 20:59 ` Peter Zijlstra
2007-11-15 21:12 ` Peter Zijlstra
2007-11-15 21:14 ` Linus Torvalds
2007-11-15 21:26 ` Linus Torvalds [this message]
2007-11-15 21:26 ` Peter Zijlstra
2007-11-15 21:47 ` Linus Torvalds
2007-11-15 22:11 ` Chris Friesen
2007-11-15 22:31 ` Linus Torvalds
2007-11-15 22:24 ` Rob Mueller
2007-11-18 23:13 ` Daniel Phillips
2007-11-19 3:41 ` Bron Gondwana
2007-11-16 0:48 ` Alan Cox
2007-11-21 21:25 ` Jan Engelhardt
2007-11-19 3:54 ` Bron Gondwana
2007-11-22 3:42 ` [PATCH 1/1] mm: add dirty_highmem option Bron Gondwana
2007-11-26 17:53 ` Linus Torvalds
2007-11-27 1:30 ` Bron Gondwana
2007-11-27 4:54 ` Andrew Morton
2007-11-27 5:24 ` Bron Gondwana
2007-11-27 5:53 ` Andrew Morton
2007-11-27 12:10 ` dirty highmem calculation sysctl name (Was: [PATCH 1/1] mm: add dirty_highmem option) Bron Gondwana
2007-11-27 13:06 ` [PATCH] mm/page-writeback - highmem_is_dirtyable option (replaces dirty_highmem patch) Bron Gondwana
2007-11-21 23:51 ` mmap dirty limits on 32 bit kernels (Was: [BUG] New Kernel Bugs) Bron Gondwana
2007-11-22 2:16 ` Bron Gondwana
2007-11-13 19:32 ` [BUG] New Kernel Bugs Russell King
2007-11-13 20:13 ` Adrian Bunk
2007-11-13 23:29 ` Russell King
2007-11-13 23:38 ` Andrew Morton
2007-11-13 20:52 ` Andrew Morton
2007-11-13 22:18 ` Russell King
2007-11-13 22:32 ` Andrew Morton
2007-11-13 23:09 ` Russell King
2007-11-13 23:17 ` Andrew Morton
2007-11-14 1:55 ` David Miller
2007-11-14 2:27 ` Andrew Morton
2007-11-14 3:47 ` David Miller
2007-11-14 8:30 ` Russell King
2007-11-14 9:55 ` Russell King
2007-11-14 10:07 ` David Miller
2007-11-14 11:46 ` [alsa-devel] " Rene Herman
2007-11-14 11:56 ` David Miller
2007-11-14 12:01 ` David Miller
2007-11-14 8:25 ` Moderated list (Was: Re: [BUG] New Kernel Bugs) Takashi Iwai
2007-11-14 12:21 ` Rene Herman
2007-11-14 9:47 ` Takashi Iwai
2007-11-14 23:23 ` Moderated list David Miller
2007-11-15 6:09 ` Rene Herman
2007-11-14 12:12 ` [alsa-devel] [BUG] New Kernel Bugs Rene Herman
2007-11-14 12:09 ` Rene Herman
2007-11-15 4:16 ` Bron Gondwana
2007-11-15 5:59 ` Rene Herman
2007-11-15 12:02 ` Bron Gondwana
2007-11-15 12:26 ` Rene Herman
2007-11-15 13:00 ` Jörn Engel
2007-11-15 14:29 ` Rene Herman
2007-11-15 13:17 ` Olivier Galibert
2007-11-15 9:34 ` Takashi Iwai
2007-11-14 19:44 ` Russell King
2007-11-16 22:16 ` Use *poof* for linux-omap (Was: [BUG] New Kernel Bugs) Tony Lindgren
2007-11-17 0:45 ` Use *poof* for linux-omap David Miller
2007-11-18 20:01 ` Tony Lindgren
2007-11-14 5:56 ` [BUG] New Kernel Bugs Sam Ravnborg
2007-11-14 5:59 ` Sam Ravnborg
2007-11-14 6:13 ` David Miller
2007-11-13 13:40 ` Ingo Molnar
2007-11-13 14:08 ` Mark Lord
2007-11-13 15:24 ` Giacomo A. Catenazzi
2007-11-13 15:57 ` Ray Lee
2007-11-13 17:01 ` Adrian Bunk
2007-11-13 17:50 ` Romano Giannetti
2007-11-13 22:03 ` Frans Pop
2007-11-13 15:52 ` Benoit Boissinot
2007-11-13 16:49 ` Ingo Molnar
2007-11-13 17:13 ` Theodore Tso
2007-11-13 17:30 ` Alan Cox
2007-11-13 17:33 ` Larry Finger
2007-11-13 18:55 ` Theodore Tso
2007-11-13 20:07 ` Larry Finger
2007-11-13 17:56 ` Adrian Bunk
2007-11-13 18:57 ` Gabriel C
2007-11-14 0:41 ` Denys Vlasenko
2007-11-14 0:39 ` Denys Vlasenko
2007-11-14 7:27 ` Adrian Bunk
2007-11-14 7:46 ` Denys Vlasenko
2007-11-14 13:30 ` Matthew Wilcox
2007-11-14 13:35 ` Hannes Reinecke
2007-11-14 21:39 ` Denys Vlasenko
2007-11-14 21:58 ` Gabriel C
2007-11-14 18:27 ` Kok, Auke
2007-11-14 16:55 ` Jan Evert van Grootheest
2007-11-14 23:23 ` Daniel Barkalow
2007-11-15 15:30 ` Theodore Tso
2007-11-15 16:19 ` Daniel Barkalow
2007-11-16 8:20 ` Romano Giannetti
2007-11-16 18:20 ` Daniel Barkalow
2007-11-16 19:46 ` Theodore Tso
2007-11-17 12:20 ` Adrian Bunk
2007-11-18 18:01 ` Theodore Tso
2007-11-13 16:46 ` Ingo Molnar
2007-11-13 17:50 ` Mark Lord
2007-11-13 18:12 ` Adrian Bunk
2007-11-13 18:18 ` Mark Lord
2007-11-13 18:36 ` Adrian Bunk
2007-11-13 18:47 ` Mark Lord
2007-11-13 19:04 ` Adrian Bunk
2007-11-13 19:12 ` Mark Lord
2007-11-13 19:30 ` Adrian Bunk
2007-11-13 19:46 ` Russell King
2007-11-13 20:04 ` Adrian Bunk
2007-11-13 19:26 ` Mark Lord
2007-11-13 20:00 ` Adrian Bunk
2007-11-13 20:13 ` Mark Lord
2007-11-13 21:20 ` Adrian Bunk
2007-11-13 21:12 ` Alan Cox
2007-11-14 0:52 ` Chuck Ebbert
2007-11-14 1:11 ` Stephen Hemminger
2007-11-14 2:10 ` Andrew Morton
2007-11-14 1:10 ` David Miller
2007-11-14 1:18 ` Peter Stuge
2007-11-13 18:17 ` Peter Zijlstra
2007-11-13 18:39 ` Matthew Wilcox
2007-11-13 18:43 ` Mark Lord
2007-11-13 18:49 ` Matthew Wilcox
2007-11-13 18:54 ` Mark Lord
2007-11-13 22:09 ` Rafael J. Wysocki
2007-11-14 14:30 ` Ingo Molnar
2007-11-14 14:49 ` Larry Finger
2007-11-18 12:44 ` size of git repository (was Re: [BUG] New Kernel Bugs) Pavel Machek
2007-11-18 12:58 ` Rene Herman
2007-11-18 14:35 ` James Bottomley
2007-11-18 15:19 ` Rene Herman
2007-11-18 14:56 ` Ingo Molnar
2007-11-19 4:43 ` Willy Tarreau
2007-11-13 19:37 ` [BUG] New Kernel Bugs Russell King
2007-11-13 20:18 ` Mark Lord
2007-11-13 21:33 ` Jörn Engel
2007-11-13 21:56 ` Andrew Morton
2007-11-13 22:24 ` Jörn Engel
2007-11-13 22:43 ` Andrew Morton
2007-11-13 22:29 ` Mark Lord
2007-11-13 23:40 ` Russell King
2007-11-14 1:56 ` David Miller
2007-11-14 0:34 ` Denys Vlasenko
2007-11-15 3:06 ` Neil Brown
2007-11-13 16:55 ` Randy Dunlap
2007-11-14 14:08 ` Ingo Molnar
2007-11-14 17:38 ` Randy Dunlap
2007-11-14 18:23 ` J. Bruce Fields
2007-11-15 2:50 ` Neil Brown
2007-11-16 0:05 ` J. Bruce Fields
2007-11-14 20:16 ` Ingo Molnar
2007-11-14 20:29 ` Randy Dunlap
2007-11-14 20:37 ` Ingo Molnar
2007-11-14 21:05 ` Randy Dunlap
2007-11-14 19:56 ` David Miller
2007-11-14 20:09 ` James Bottomley
2007-11-14 20:54 ` Ingo Molnar
2007-11-14 20:48 ` Ingo Molnar
2007-11-14 21:05 ` david
2007-11-13 11:47 ` Jarek Poplawski
2007-11-13 13:58 ` Mark Lord
2007-11-13 14:18 ` Mark Lord
2007-11-13 16:08 ` Thomas Gleixner
2007-11-13 16:07 ` Thomas Gleixner
2007-11-13 17:47 ` Mark Lord
2007-11-15 16:32 ` [BUG] Strange 1-second pauses during Resume-from-RAM Mark Lord
2007-11-15 16:49 ` Ray Lee
2007-11-15 16:51 ` Mark Lord
2007-11-15 16:53 ` Mark Lord
2007-11-15 18:14 ` Pavel Machek
2007-11-15 17:31 ` Mark Lord
2007-11-15 19:34 ` Ingo Molnar
2007-11-15 19:36 ` Ingo Molnar
2007-11-15 22:23 ` Mark Lord
2007-11-16 5:55 ` Ingo Molnar
2007-11-16 7:15 ` Ingo Molnar
2007-11-16 8:21 ` Ingo Molnar
2007-11-16 11:23 ` Ingo Molnar
2007-11-16 11:53 ` Mike Galbraith
2007-11-16 12:43 ` Ingo Molnar
2007-11-16 12:58 ` [patch] snd hda suspend latency: shorten codec read Ingo Molnar
2007-11-16 13:31 ` Rafael J. Wysocki
2007-11-16 14:21 ` Takashi Iwai
2007-11-16 19:06 ` [BUG] Strange 1-second pauses during Resume-from-RAM Mark Lord
2007-11-16 18:35 ` Mark Lord
2007-11-30 20:12 ` Mark Lord
2007-11-30 12:56 ` Jörn Engel
2007-11-30 13:35 ` Ingo Molnar
2007-11-30 13:43 ` Ingo Molnar
2007-11-30 18:35 ` Jörn Engel
2007-11-30 18:46 ` Ingo Molnar
2007-12-01 15:16 ` Jörn Engel
2007-12-01 18:32 ` Ingo Molnar
2007-12-01 20:47 ` Jörn Engel
2007-12-01 20:54 ` Ingo Molnar
2007-12-01 23:41 ` Jörn Engel
2007-12-02 8:56 ` Ingo Molnar
2007-12-02 11:31 ` Jörn Engel
2007-12-02 12:31 ` Jörn Engel
2007-12-02 13:57 ` Ingo Molnar
2007-12-02 14:46 ` Jörn Engel
2007-12-02 15:44 ` Ingo Molnar
2007-12-02 13:57 ` Ingo Molnar
2007-12-02 14:11 ` Jörn Engel
2007-12-02 15:47 ` Ingo Molnar
2007-12-02 19:55 ` Jörn Engel
2007-12-02 20:07 ` Ingo Molnar
2007-12-02 20:30 ` Jörn Engel
2007-12-02 20:45 ` Ingo Molnar
2007-12-02 21:08 ` Jörn Engel
2007-12-02 21:10 ` Jörn Engel
2007-12-02 21:19 ` Ingo Molnar
2007-12-03 0:57 ` Jörn Engel
2007-12-04 0:06 ` Jörn Engel
2007-12-04 9:34 ` Ingo Molnar
2007-11-30 15:49 ` Jörn Engel
2007-11-15 20:27 ` Rafael J. Wysocki
2007-11-18 16:10 ` Mark Lord
2007-11-18 16:21 ` Ingo Molnar
2007-11-18 17:37 ` Mark Lord
2007-11-13 17:54 ` [BUG] New Kernel Bugs Mark Lord
2007-11-13 22:46 ` Thomas Gleixner
2007-11-13 23:37 ` Mark Lord
2007-11-13 18:10 ` Russell King
2007-11-13 18:25 ` Alan Cox
2007-11-13 22:34 ` Russell King
2007-11-15 20:16 ` Ben Dooks
2007-11-13 15:21 ` Bartlomiej Zolnierkiewicz
2007-11-13 15:33 ` James Bottomley
2007-11-13 16:43 ` Randy Dunlap
2007-11-13 17:46 ` Martin Bligh
2007-11-13 18:47 ` Andrew Morton
2007-11-14 5:07 ` David Miller
2007-11-13 15:36 ` Alan Cox
2007-11-13 17:49 ` Jan Kara
2007-11-13 18:04 ` Russell King
2007-11-14 12:46 ` Jiri Kosina
2007-11-14 13:24 ` Pavel Machek
2007-11-14 14:14 ` Fabio Comolli
2007-11-14 19:52 ` Russell King
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