From: Linus Torvalds <torvalds@transmeta.com>
To: "Stephen C. Tweedie" <sct@redhat.com>
Cc: linux-mm@kvack.org
Subject: Re: MM deadlock [was: Re: arca-vm-8...]
Date: Mon, 25 Jan 1999 10:43:46 -0800 (PST) [thread overview]
Message-ID: <Pine.LNX.3.95.990125103135.21082F-100000@penguin.transmeta.com> (raw)
In-Reply-To: <199901251625.QAA04452@dax.scot.redhat.com>
On Mon, 25 Jan 1999, Stephen C. Tweedie wrote:
>
> The changes are very similar to the self-tuning clock counter we had in
> those ac* vms. The modified shrink_mmap() just avoids decrementing the
> count for locked, non-DMA (if GFP_DMA) or multiply-mapped pages. The
> effect is to avoid counting memory mapped pages when we trim cache. In
> low memory, this allows us to keep trimming back the "excess" unmapped
> pure cache pages even if a large fraction of physical memory is occupied
> by mapped pages.
Parts of your patch makes sense, other parts make no sense at all.
For example, the "multiply by two" that you removed, is done in order to
make shrink_mmap() look at all pages when given a priority of zero. Your
patch makes it possible that shrink_mmap() wouldn't have looked at all
pages, because count is still decremented before looking at "referenced"
I don't think that's actually a problem, because before we call
shrink_mmap() with argument 0, we'll have called it many times before, and
that together with the fact that you changed the count to not be
decremented for shared pages makes the "problem" fairly academic. So my
only objection is basically that I think you mixed up the behaviour of the
new patch with the (original) patch of yours that made count decrements
conditional on the PG_referenced bit.
Basically, this is _very_ different from the self-tuning clock you
proposed earlier: your earlier patch had the explanation that you wanted
to more quickly go through referenced pages, while this one goes through
_shared_ pages more quickly. Big difference.
I like the second way of thinking about it a lot more, though. And it may
be that even though you _thought_ that the first one was due to reference
counting, the shared page issue was the more important one.
As far as I can see, this patch essentially makes us more likely to keep
shared pages - somehting I wholeheartedly agree with, and I'll apply it. I
just wanted to point out that I think you're making up the explanations
for your patches as you go along, and that this is NOT the same
explanation you had for your earlier patch that did a very similar thing.
Sounds like you made up the explanations after making the patch.
Linus
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next prev parent reply other threads:[~1999-01-25 18:44 UTC|newest]
Thread overview: 243+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <199812290146.BAA12687@terrorserver.swansea.linux.org.uk>
1998-12-31 18:00 ` 2.2.0 Bug summary Andrea Arcangeli
1998-12-31 18:34 ` [patch] new-vm improvement [Re: 2.2.0 Bug summary] Andrea Arcangeli
1999-01-01 0:16 ` Steve Bergman
1999-01-01 17:16 ` Andrea Arcangeli
1999-01-01 16:44 ` Andrea Arcangeli
1999-01-01 20:02 ` Andrea Arcangeli
1999-01-01 23:46 ` Steve Bergman
1999-01-02 6:55 ` Linus Torvalds
1999-01-02 8:33 ` Steve Bergman
1999-01-02 14:48 ` Andrea Arcangeli
1999-01-02 15:38 ` Andrea Arcangeli
1999-01-02 18:10 ` Linus Torvalds
1999-01-02 20:52 ` Andrea Arcangeli
1999-01-03 2:59 ` Andrea Arcangeli
1999-01-04 18:08 ` [patch] arca-vm-6, killed kswapd [Re: [patch] new-vm improvement , [Re: 2.2.0 Bug summary]] Andrea Arcangeli
1999-01-04 20:56 ` Linus Torvalds
1999-01-04 21:10 ` Rik van Riel
1999-01-04 22:04 ` Alan Cox
1999-01-04 21:55 ` Linus Torvalds
1999-01-04 22:51 ` Andrea Arcangeli
1999-01-05 0:32 ` Andrea Arcangeli
1999-01-05 0:52 ` Zlatko Calusic
1999-01-05 3:02 ` Zlatko Calusic
1999-01-05 11:49 ` Andrea Arcangeli
1999-01-05 13:23 ` Zlatko Calusic
1999-01-05 15:42 ` Andrea Arcangeli
1999-01-05 16:16 ` Zlatko Calusic
1999-01-05 15:35 ` arca-vm-8 [Re: [patch] arca-vm-6, killed kswapd [Re: [patch] new-vm , improvement , [Re: 2.2.0 Bug summary]]] Andrea Arcangeli
1999-01-06 14:48 ` Andrea Arcangeli
1999-01-06 23:31 ` Andrea Arcangeli
1999-01-07 3:32 ` Results: 2.2.0-pre5 vs arcavm10 vs arcavm9 vs arcavm7 Steve Bergman
1999-01-07 12:02 ` Andrea Arcangeli
1999-01-07 20:27 ` Linus Torvalds
1999-01-07 23:56 ` Andrea Arcangeli
1999-01-07 17:35 ` Linus Torvalds
1999-01-07 18:44 ` Zlatko Calusic
1999-01-07 19:33 ` Linus Torvalds
1999-01-07 21:10 ` Zlatko Calusic
1999-01-07 19:38 ` Zlatko Calusic
1999-01-07 19:40 ` Andrea Arcangeli
1999-01-09 6:28 ` 2.2.0-pre[56] swap performance poor with > 1 thrashing task Dax Kelson
1999-01-09 6:32 ` Zlatko Calusic
1999-01-09 6:44 ` Linus Torvalds
1999-01-09 18:58 ` Andrea Arcangeli
1999-01-11 9:21 ` Buffer handling (setting PG_referenced on access) Zlatko Calusic
1999-01-11 17:44 ` Linus Torvalds
1999-01-11 20:14 ` Zlatko Calusic
1999-01-16 17:35 ` 2.2.0-pre[56] swap performance poor with > 1 thrashing task Andrea Arcangeli
1999-01-09 7:48 ` Benjamin Redelings I
1999-01-09 6:53 ` Linus Torvalds
1999-01-09 22:39 ` Results: pre6 vs pre6+zlatko's_patch vs pre5 vs arcavm13 Steve Bergman
1999-01-10 0:28 ` Steve Bergman
1999-01-10 5:35 ` Linus Torvalds
1999-01-10 18:33 ` Andrea Arcangeli
1999-01-10 18:43 ` Steve Bergman
1999-01-10 19:08 ` Linus Torvalds
1999-01-10 19:23 ` Vladimir Dergachev
1999-01-10 20:09 ` Andrea Arcangeli
1999-01-10 20:29 ` Steve Bergman
1999-01-10 21:41 ` Linus Torvalds
1999-01-10 23:33 ` testing/pre-7 and do_poll() Chip Salzenberg
1999-01-11 6:02 ` Linus Torvalds
1999-01-11 6:26 ` Chip Salzenberg
1999-01-11 6:46 ` Linus Torvalds
1999-01-11 6:59 ` Chip Salzenberg
1999-01-11 7:02 ` Linus Torvalds
1999-01-11 22:08 ` Shawn Leas
1999-01-11 22:13 ` Linus Torvalds
1999-01-12 0:25 ` estafford
1999-01-12 8:25 ` Shawn Leas
1999-01-12 7:06 ` Gregory Maxwell
1999-01-11 20:20 ` Adam Heath
1999-01-11 16:57 ` Results: pre6 vs pre6+zlatko's_patch vs pre5 vs arcavm13 Steve Bergman
1999-01-11 19:36 ` Andrea Arcangeli
1999-01-11 23:03 ` Andrea Arcangeli
1999-01-11 23:38 ` Zlatko Calusic
1999-01-12 2:02 ` Steve Bergman
1999-01-12 3:21 ` Results: Zlatko's new vm patch Steve Bergman
1999-01-12 5:33 ` Linus Torvalds
1999-01-12 14:49 ` Andrea Arcangeli
1999-01-12 16:58 ` Joseph Anthony
1999-01-12 18:16 ` Stephen C. Tweedie
1999-01-12 20:15 ` Michael K Vance
1999-01-13 19:25 ` Stephen C. Tweedie
1999-01-12 18:24 ` Michael K Vance
1999-01-13 0:01 ` Where to find pre7. Was: " Robert Thorncrantz
1999-01-13 20:47 ` [patch] arca-vm-19 [Re: Results: Zlatko's new vm patch] Andrea Arcangeli
1999-01-14 12:30 ` Andrea Arcangeli
1999-01-15 23:56 ` [patch] NEW: arca-vm-21, swapout via shrink_mmap using PG_dirty Andrea Arcangeli
1999-01-16 16:49 ` Andrea Arcangeli
1999-01-17 23:47 ` Andrea Arcangeli
1999-01-18 5:11 ` Linus Torvalds
1999-01-18 7:28 ` Eric W. Biederman
1999-01-18 10:00 ` Andrea Arcangeli
1999-01-18 9:15 ` Andrea Arcangeli
1999-01-18 17:49 ` Linus Torvalds
1999-01-18 19:22 ` Andrea Arcangeli
1999-01-10 20:40 ` Results: pre6 vs pre6+zlatko's_patch vs pre5 vs arcavm13 Andrea Arcangeli
1999-01-10 20:50 ` Linus Torvalds
1999-01-10 21:01 ` Andrea Arcangeli
1999-01-10 21:51 ` Steve Bergman
1999-01-10 22:50 ` Results: arcavm15, et. al Steve Bergman
1999-01-11 0:20 ` Steve Bergman
1999-01-11 13:21 ` Andrea Arcangeli
1999-01-11 3:47 ` Results: pre6 vs pre6+zlatko's_patch vs pre5 vs arcavm13 Gregory Maxwell
1999-01-06 23:35 ` arca-vm-8 [Re: [patch] arca-vm-6, killed kswapd [Re: [patch] new-vm , improvement , [Re: 2.2.0 Bug summary]]] Linus Torvalds
1999-01-07 4:30 ` Eric W. Biederman
1999-01-07 17:56 ` Linus Torvalds
1999-01-07 18:18 ` Rik van Riel
1999-01-07 19:19 ` arca-vm-8 [Re: [patch] arca-vm-6, killed kswapd [Re: [patch] Alan Cox
1999-01-07 18:55 ` arca-vm-8 [Re: [patch] arca-vm-6, killed kswapd [Re: [patch] new-vm , improvement , [Re: 2.2.0 Bug summary]]] Zlatko Calusic
1999-01-07 22:57 ` Linus Torvalds
1999-01-08 1:16 ` Linus Torvalds
1999-01-08 10:45 ` Andrea Arcangeli
1999-01-08 19:06 ` Linus Torvalds
1999-01-09 9:43 ` MM deadlock [was: Re: arca-vm-8...] Savochkin Andrey Vladimirovich
1999-01-09 18:00 ` Linus Torvalds
1999-01-09 18:41 ` Andrea Arcangeli
1999-01-10 21:41 ` Stephen C. Tweedie
1999-01-10 21:47 ` Linus Torvalds
1999-01-09 21:50 ` Linus Torvalds
1999-01-10 11:56 ` Savochkin Andrey Vladimirovich
1999-01-10 17:59 ` Andrea Arcangeli
1999-01-10 22:33 ` Stephen C. Tweedie
1999-01-10 16:59 ` Stephen C. Tweedie
1999-01-10 18:13 ` Andrea Arcangeli
1999-01-10 18:35 ` Linus Torvalds
1999-01-10 19:45 ` Alan Cox
1999-01-10 19:03 ` Andrea Arcangeli
1999-01-10 21:39 ` Stephen C. Tweedie
1999-01-10 19:09 ` Linus Torvalds
1999-01-10 20:33 ` Alan Cox
1999-01-10 20:07 ` Linus Torvalds
1999-01-10 22:18 ` Stephen C. Tweedie
1999-01-10 22:49 ` Stephen C. Tweedie
1999-01-11 6:04 ` Eric W. Biederman
1999-01-12 16:06 ` Stephen C. Tweedie
1999-01-12 17:54 ` Linus Torvalds
1999-01-12 18:44 ` Zlatko Calusic
1999-01-12 19:05 ` Andrea Arcangeli
1999-01-13 17:48 ` Stephen C. Tweedie
1999-01-13 18:07 ` 2.2.0-pre6 ain't nice =( Kalle Andersson
1999-01-13 19:05 ` MM deadlock [was: Re: arca-vm-8...] Alan Cox
1999-01-13 19:23 ` MOLNAR Ingo
1999-01-13 19:26 ` Andrea Arcangeli
1999-01-14 11:02 ` Mike Jagdis
1999-01-14 22:38 ` Andrea Arcangeli
1999-01-15 7:40 ` Agus Budy Wuysang
1999-01-14 10:48 ` Mike Jagdis
1999-01-12 21:46 ` Rik van Riel
1999-01-13 6:52 ` Zlatko Calusic
1999-01-13 13:45 ` Andrea Arcangeli
1999-01-13 13:58 ` Chris Evans
1999-01-13 15:07 ` Andrea Arcangeli
1999-01-13 22:11 ` Stephen C. Tweedie
1999-01-13 14:59 ` Rik van Riel
1999-01-13 18:10 ` Andrea Arcangeli
1999-01-13 22:14 ` Stephen C. Tweedie
1999-01-14 14:53 ` Dr. Werner Fink
1999-01-21 16:50 ` Stephen C. Tweedie
1999-01-21 19:53 ` Andrea Arcangeli
1999-01-22 13:55 ` Stephen C. Tweedie
1999-01-22 19:45 ` Andrea Arcangeli
1999-01-23 23:20 ` Alan Cox
1999-01-24 0:19 ` Linus Torvalds
1999-01-24 18:33 ` Gregory Maxwell
1999-01-25 0:21 ` Linus Torvalds
1999-01-25 1:28 ` Alan Cox
1999-01-25 3:35 ` pmonta
1999-01-25 4:17 ` Linus Torvalds
1999-01-24 20:33 ` Alan Cox
1999-01-25 0:27 ` Linus Torvalds
1999-01-25 1:38 ` Alan Cox
1999-01-25 1:04 ` Andrea Arcangeli
1999-01-25 2:10 ` Alan Cox
1999-01-25 3:16 ` Garst R. Reese
1999-01-25 10:49 ` Alan Cox
1999-01-25 14:06 ` Rik van Riel
1999-01-25 21:59 ` Gerard Roudier
1999-01-26 11:45 ` Thomas Sailer
1999-01-26 20:48 ` Gerard Roudier
1999-01-26 21:24 ` Thomas Sailer
1999-01-27 0:25 ` David Lang
1999-01-27 16:05 ` Stephen C. Tweedie
1999-01-27 20:11 ` Gerard Roudier
1999-01-26 13:06 ` Stephen C. Tweedie
1999-01-26 14:28 ` Alan Cox
1999-01-26 14:15 ` MOLNAR Ingo
1999-01-26 14:36 ` yodaiken
1999-01-26 15:21 ` MOLNAR Ingo
1999-01-27 10:31 ` yodaiken
1999-01-26 15:46 ` Alan Cox
1999-01-26 16:45 ` Stephen C. Tweedie
1999-01-30 7:01 ` yodaiken
1999-02-01 13:07 ` Stephen C. Tweedie
1999-01-26 16:37 ` Stephen C. Tweedie
1999-01-27 11:35 ` Jakub Jelinek
1999-01-26 14:21 ` Rik van Riel
1999-01-25 16:25 ` Stephen C. Tweedie
1999-01-25 16:52 ` Andrea Arcangeli
1999-01-25 18:27 ` Linus Torvalds
1999-01-25 18:43 ` Stephen C. Tweedie
1999-01-25 18:49 ` Linus Torvalds
1999-01-25 18:43 ` Linus Torvalds [this message]
1999-01-25 19:15 ` Stephen C. Tweedie
1999-01-26 1:57 ` Andrea Arcangeli
1999-01-26 18:37 ` Andrea Arcangeli
1999-01-27 12:13 ` Stephen C. Tweedie
1999-01-22 16:29 ` Eric W. Biederman
1999-01-25 13:14 ` Dr. Werner Fink
1999-01-25 17:56 ` Stephen C. Tweedie
1999-01-25 19:10 ` Andrea Arcangeli
1999-01-25 20:49 ` Dr. Werner Fink
1999-01-25 20:56 ` Linus Torvalds
1999-01-26 12:23 ` Rik van Riel
1999-01-26 15:44 ` Andrea Arcangeli
1999-01-27 14:52 ` Stephen C. Tweedie
1999-01-28 19:12 ` Dr. Werner Fink
1999-01-13 17:55 ` [PATCH] " Stephen C. Tweedie
1999-01-13 18:52 ` Andrea Arcangeli
1999-01-13 22:10 ` Stephen C. Tweedie
1999-01-13 22:30 ` Linus Torvalds
1999-01-11 11:20 ` Pavel Machek
1999-01-11 17:35 ` Stephen C. Tweedie
1999-01-11 14:11 ` Savochkin Andrey Vladimirovich
1999-01-11 17:55 ` Linus Torvalds
1999-01-11 18:37 ` Andrea Arcangeli
1999-01-08 2:56 ` arca-vm-8 [Re: [patch] arca-vm-6, killed kswapd [Re: [patch] new-vm , improvement , [Re: 2.2.0 Bug summary]]] Eric W. Biederman
1999-01-09 0:50 ` David S. Miller
1999-01-09 2:13 ` Stephen C. Tweedie
1999-01-09 2:34 ` Andrea Arcangeli
1999-01-09 9:30 ` Stephen C. Tweedie
1999-01-09 12:11 ` Andrea Arcangeli
1999-01-07 14:11 ` Andrea Arcangeli
1999-01-07 18:19 ` Linus Torvalds
1999-01-07 20:35 ` Andrea Arcangeli
1999-01-07 23:51 ` Linus Torvalds
1999-01-08 0:04 ` Andrea Arcangeli
1999-01-04 22:43 ` [patch] arca-vm-6, killed kswapd [Re: [patch] new-vm improvement , [Re: 2.2.0 Bug summary]] Andrea Arcangeli
1999-01-04 22:29 ` Andrea Arcangeli
1999-01-05 13:33 ` [patch] new-vm improvement [Re: 2.2.0 Bug summary] Ben McCann
1999-01-02 20:04 ` Steve Bergman
1999-01-02 3:03 ` Andrea Arcangeli
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