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From: ebiederm+eric@ccr.net (Eric W. Biederman)
To: Linus Torvalds <torvalds@transmeta.com>
Cc: Andrea Arcangeli <andrea@e-mind.com>,
	Steve Bergman <steve@netplus.net>,
	dlux@dlux.sch.bme.hu, "Nicholas J. Leon" <nicholas@binary9.net>,
	Kalle Andersson <kalle@sslug.dk>,
	brent verner <damonbrent@earthlink.net>,
	"Garst R. Reese" <reese@isn.net>,
	Kalle Andersson <kalle.andersson@mbox303.swipnet.se>,
	Zlatko Calusic <Zlatko.Calusic@CARNet.hr>,
	Ben McCann <bmccann@indusriver.com>,
	bredelin@ucsd.edu, linux-kernel@vger.rutgers.edu,
	linux-mm@kvack.org, Alan Cox <alan@lxorguk.ukuu.org.uk>,
	"Stephen C. Tweedie" <sct@redhat.com>,
	Heinz Mauelshagen <mauelsha@ez-darmstadt.telekom.de>,
	Max <max@Linuz.sns.it>
Subject: Re: [patch] NEW: arca-vm-21, swapout via shrink_mmap using PG_dirty
Date: 18 Jan 1999 01:28:38 -0600	[thread overview]
Message-ID: <m1n23hdopl.fsf@flinx.ccr.net> (raw)
In-Reply-To: Linus Torvalds's message of "Sun, 17 Jan 1999 21:11:45 -0800 (PST)"

>>>>> "LT" == Linus Torvalds <torvalds@transmeta.com> writes:


LT> Note that what I really wanted to use PG_dirty for was not for normal
LT> page-outs, but for shared mappings of files. 

LT> For normal page-out activity, the PG_dirty thing isn't a win, simply
LT> because (a) it doesn't actually buy us anything (we might as well do it 
LT> from the page tables directly) 

If we combine it with early scanning of the page tables,  it should allow us
to perform I/O before we need the memory.  While not bogging down processes.

LT> and (b) as you noticed, it increases fragmentation.

This is only because he didn't implement any kind of request queue.
A fifo queue of pages to write would have keep performance up at current levels.

LT> The reason PG_dirty should be a win for shared mappings is: (a) it gets
LT> rid of the file write semaphore problem in a very clean way and 

Nope.  Because we can still have some try to write to file X.
That write needs memory, and we try to swapout a mapping of file X.
Unless you believe it implies the write outs then must use a seperate process.

LT> (b) it
LT> reduces the number of IO requests for mappings that are writable for
LT> multiple contexts (right now we will actually do multiple page-outs, one
LT> for each shared mapping that has dirtied the page). 

With a reasonable proximity in time even that isn't necessary because of the buffer
cache.  This is only a real issue for filesystems that don't implement good
write cachine on their own.  In which case the primary thing to fix is
caching for those filesystems.  We can use PG_dirty for that case too, but
the emphasis is different.

LT> I looked at the problem, and PG_dirty for shared mappings should be
LT> reasonably simple. However, I don't think I can do it for 2.2 simply
LT> because it involves some VFS interface changes (it requires that you can
LT> use the pame_map[] information and nothing else to page out: we have the
LT> inode and the offset which actually is enough data to do it, but we don't
LT> have a good enough "inode->i_op->writepage()" setup yet).

At least in part because for NFS you need who is doing the write, which
we currently store with a struct file.  To get it correct we really
need a two level setup.  Level 1 per pte to enter in the write request.
Level 2 per page to acutally write it out.

If there are conflicts, (not the same user, etc) Level 1 can handle them.

If I have any luck I should have a draft of a complete set of changes to do
all of this for 2.3 in about a month.  I have been working on this in the
backgroud for quite a while.

Eric




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  reply	other threads:[~1999-01-18  9:45 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 [this message]
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
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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