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From: Andrea Arcangeli <andrea@suse.de>
To: Wayne Whitney <whitney@math.berkeley.edu>
Cc: Szabolcs Szakacsits <szaka@f-secure.com>,
	LKML <linux-kernel@vger.kernel.org>, Andi Kleen <ak@suse.de>
Subject: Re: Subtle MM bug
Date: Mon, 8 Jan 2001 23:15:58 +0100	[thread overview]
Message-ID: <20010108231558.A27646@athlon.random> (raw)
In-Reply-To: <Pine.LNX.4.30.0101082207290.3435-100000@fs129-124.f-secure.com> <Pine.LNX.4.30.0101081357130.966-100000@mf2.private>
In-Reply-To: <Pine.LNX.4.30.0101081357130.966-100000@mf2.private>; from whitney@math.berkeley.edu on Mon, Jan 08, 2001 at 02:00:19PM -0800

On Mon, Jan 08, 2001 at 02:00:19PM -0800, Wayne Whitney wrote:
> I'd ask if this jives with your theory:  if I configure the linux kernel
> to be able to use 2GB of RAM, then the 870MB limit becomes much lower, to
> 230MB.

It's because the virtual address space for userspace tasks gets reduced
from 3G to 2G to give an additional giga of direct mapping to the kernel.

Also the other limit you hit (at around 800mbyte) is partly because
of the too low userspace virtual address space.

You can use this hack by me to allow the tasks to grow up to 3.5G per task on
IA32 on 2.4.0 (equivalent hack exists for 2.2.19pre6aa1 with bigmem, btw it
makes sense also without bigmem if you have lots of swap, that's all about
virtual memory not physical RAM).  However it doesn't work with PAE enabled
yet.

	ftp://ftp.us.kernel.org/pub/linux/kernel/people/andrea/patches/v2.4/2.4.0-test11-pre5/per-process-3.5G-IA32-no-PAE-1

If you run your program on any 64bit architecture (in 64bit userspace mode)
supported by linux, you won't run into those per-process address space limits.

Andrea
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  reply	other threads:[~2001-01-08 22:16 UTC|newest]

Thread overview: 88+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2001-01-08 20:39 Subtle MM bug Szabolcs Szakacsits
2001-01-08 21:56 ` Wayne Whitney
2001-01-08 23:22   ` Wayne Whitney
2001-01-08 23:30     ` Andrea Arcangeli
2001-01-09  0:37       ` Linus Torvalds
2001-01-09  3:01       ` Subtle MM bug (really 830MB barrier question) Wayne Whitney
2001-01-09 20:06         ` Szabolcs Szakacsits
2001-01-09 23:45           ` Wayne Whitney
2001-01-11  0:03           ` Wayne Whitney
2001-01-11  2:46           ` [2.4.0 pre-PATCH] 830MB barrier (was: Subtle MM bug) Wayne Whitney
2001-01-08 22:00 ` Subtle MM bug Wayne Whitney
2001-01-08 22:15   ` Andrea Arcangeli [this message]
  -- strict thread matches above, loose matches on Subject: below --
2001-01-10 19:57 Chris Wing
2001-01-08  5:29 Wayne Whitney
2001-01-08  5:42 ` Andi Kleen
2001-01-08  6:04   ` Linus Torvalds
2001-01-08 17:44     ` Rik van Riel
2001-01-08 18:02       ` Linus Torvalds
2001-01-08 17:16 ` Rik van Riel
2001-01-08 17:58   ` Linus Torvalds
2001-01-08 23:41     ` Zlatko Calusic
2001-01-09  2:58       ` Linus Torvalds
2001-01-09  6:20       ` Eric W. Biederman
2001-01-09  7:27         ` Linus Torvalds
2001-01-09 11:38           ` Eric W. Biederman
2001-01-09 12:29           ` Zlatko Calusic
2001-01-09 18:47             ` Linus Torvalds
2001-01-09 19:09               ` Daniel Phillips
2001-01-09 19:29                 ` Trond Myklebust
2001-01-10 17:32                   ` Andi Kleen
2001-01-10 19:31                     ` Alan Cox
2001-01-10 19:33                       ` Andi Kleen
2001-01-10 19:40                         ` Alan Cox
2001-01-10 19:43                           ` Andi Kleen
2001-01-10 19:48                             ` Alan Cox
2001-01-10 19:48                               ` Andi Kleen
2001-01-11  9:51                               ` Trond Myklebust
2001-01-10 20:11                       ` Linus Torvalds
2001-01-11 12:56                         ` Stephen C. Tweedie
2001-01-11 13:10                           ` Andi Kleen
2001-01-11 13:12                           ` Trond Myklebust
2001-01-11 14:13                             ` Stephen C. Tweedie
2001-01-11 19:03                               ` Alexander Viro
2001-01-11 19:47                                 ` Stephen C. Tweedie
2001-01-11 19:57                                   ` Alexander Viro
2001-01-11 16:50                           ` Albert D. Cahalan
2001-01-11 17:35                             ` Stephen C. Tweedie
2001-01-11 19:38                               ` Albert D. Cahalan
2001-01-11 19:01                           ` Alexander Viro
2001-01-09 19:37                 ` Linus Torvalds
2001-01-17  8:46                 ` Rik van Riel
2001-01-25 22:51                   ` Daniel Phillips
2001-01-09 19:53               ` Simon Kirby
2001-01-09 20:08                 ` Linus Torvalds
2001-01-09 20:10                 ` Zlatko Calusic
2001-01-10  1:45               ` David Woodhouse
2001-01-10  2:26                 ` Andrea Arcangeli
2001-01-10  6:57                 ` Linus Torvalds
2001-01-10 11:46                   ` David Woodhouse
2001-01-10 14:56                     ` Andrea Arcangeli
2001-01-10 17:46                       ` Eric W. Biederman
2001-01-10 18:33                         ` Andrea Arcangeli
2001-01-17 14:26                           ` Rik van Riel
2001-01-10 19:03                         ` Linus Torvalds
2001-01-10 19:27                           ` David S. Miller
2001-01-10 19:36                           ` Alan Cox
2001-01-10 23:56                             ` David Weinehall
2001-01-11  0:24                               ` Alan Cox
2001-01-12  5:56                               ` Ralf Baechle
2001-01-12 16:10                                 ` Eric W. Biederman
2001-01-12 21:11                                   ` Russell King
2001-01-15  2:56                                     ` Ralf Baechle
2001-01-15  6:59                                       ` Eric W. Biederman
2001-01-15  2:53                                   ` Ralf Baechle
2001-01-17 14:28                           ` Rik van Riel
2001-01-18  1:23                             ` Linus Torvalds
2001-01-18 11:48                               ` Rik van Riel
2001-01-10 17:03                     ` Linus Torvalds
2001-01-11 14:36                       ` Jim Gettys
2001-01-08 21:30   ` Wayne Whitney
2001-01-07 20:59 Zlatko Calusic
2001-01-07 21:37 ` Rik van Riel
2001-01-07 22:33   ` Zlatko Calusic
2001-01-09  2:01   ` Zlatko Calusic
2001-01-17  4:48     ` Rik van Riel
2001-01-17 18:53       ` Zlatko Calusic
2001-01-18  1:32         ` Rik van Riel
2001-04-17 19:37           ` H. Peter Anvin

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