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From: Guy Sotomayor <ggs@shiresoft.com>
To: Linus Torvalds <torvalds@osdl.org>
Cc: "Andrea Arcangeli" <andrea@suse.de>,
	"Brian Gerst" <bgerst@didntduck.org>,
	"Ingo Molnar" <mingo@elte.hu>,
	"Jörn Engel" <joern@wohnheim.fh-wedel.de>,
	"Arjan van de Ven" <arjanv@redhat.com>,
	"Rik van Riel" <riel@redhat.com>,
	linux-kernel@vger.kernel.org
Subject: Re: 4k stacks in 2.6
Date: Thu, 27 May 2004 11:31:50 -0700	[thread overview]
Message-ID: <1085682709.5910.24.camel@localhost.localdomain> (raw)
In-Reply-To: <Pine.LNX.4.58.0405270754360.1648@ppc970.osdl.org>

On Thu, 2004-05-27 at 07:55, Linus Torvalds wrote:

> "minor implementation detail"?
> 
> You need to get to the thread info _some_ way, and you need to get to it
> _fast_. There are really no sane alternatives. I certainly do not want to
> play games with segments.

While segments on x86 are in general to be avoided (aka the 286
segmented memory models) they can be useful for some things in the
kernel.

Here's a couple of examples:
      * dereference gs:0 to get the thread info.  The first element in
        the structure is its linear address (ie usable for being deref'd
        off of DS).
      * use SS to enforce the stack limit.  This way you'd absolutely
        get an exception when there was a stack overflow (underflow). 
        SS gets reloaded on entry into the kernel and on interrupts
        anyway so there really shouldn't be a performance impact.  I
        haven't looked at all the (potential) gcc implications here so
        this one may not be completely doable.
-- 

TTFN - Guy


  parent reply	other threads:[~2004-05-27 18:33 UTC|newest]

Thread overview: 106+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-05-23 19:43 4g/4g for 2.6.6 Phy Prabab
2004-05-23 20:32 ` Linus Torvalds
2004-05-23 20:51   ` Jeff Garzik
2004-05-24  1:55     ` Linus Torvalds
2004-05-24  2:19       ` Jeff Garzik
2004-05-24  2:33         ` Wim Coekaerts
2004-05-31  9:51           ` Pavel Machek
2004-05-24  3:30         ` Martin J. Bligh
2004-06-01  5:52       ` Eric W. Biederman
2004-05-23 21:55   ` Phy Prabab
2004-05-24  7:05     ` Arjan van de Ven
2004-05-24  7:11       ` Phy Prabab
2004-05-24  7:24         ` Arjan van de Ven
2004-05-24  7:27           ` Phy Prabab
2004-05-24 12:01             ` Dave Jones
2004-05-24  2:39   ` William Lee Irwin III
2004-05-24  8:25   ` Ingo Molnar
2004-05-24 12:48     ` Andrea Arcangeli
2004-05-25 19:15       ` Rik van Riel
2004-05-25 19:41         ` Andrea Arcangeli
2004-05-25 19:50           ` Rik van Riel
2004-05-25 20:10             ` Rik van Riel
2004-05-25 21:15               ` Andrea Arcangeli
2004-05-26 10:33                 ` 4k stacks in 2.6 Ingo Molnar
2004-05-26 12:50                   ` Jörn Engel
2004-05-26 12:53                     ` Arjan van de Ven
2004-05-26 13:00                       ` Jörn Engel
2004-05-26 13:05                         ` Arjan van de Ven
2004-05-26 16:41                           ` Jörn Engel
2004-05-27 12:45                             ` Ingo Molnar
2004-05-27 13:59                               ` Andrea Arcangeli
2004-05-27 14:03                                 ` Arjan van de Ven
2004-05-27 14:42                                   ` Andrea Arcangeli
2004-06-02 19:40                                     ` Bill Davidsen
2004-05-27 14:18                                 ` Brian Gerst
2004-05-27 14:50                                   ` Andrea Arcangeli
2004-05-27 14:55                                     ` Linus Torvalds
2004-05-27 15:39                                       ` Andrea Arcangeli
2004-05-27 18:31                                       ` Guy Sotomayor [this message]
2004-05-27 19:26                                         ` Brian Gerst
2004-06-01  5:56                             ` 4k stacks in 2.6 [worst offenders] Jörn Engel
2004-06-01  6:02                               ` [RFC PATCH] explicitly mark recursion count Jörn Engel
2004-06-01 12:20                                 ` Pavel Machek
2004-06-01 13:27                                   ` Jörn Engel
2004-06-01 13:32                                     ` Pavel Machek
2004-06-01 13:37                                       ` Jörn Engel
2004-06-01 19:48                                         ` Horst von Brand
2004-06-01 19:29                                   ` Horst von Brand
2004-06-01 19:58                                     ` Linus Torvalds
2004-06-02 13:16                                       ` Jörn Engel
2004-06-02 14:15                                         ` Linus Torvalds
2004-06-02 14:27                                           ` Jörn Engel
2004-06-02 14:45                                             ` Linus Torvalds
2004-06-02 15:04                                               ` Jörn Engel
2004-06-02 15:12                                                 ` Linus Torvalds
2004-06-02 15:27                                                   ` Jörn Engel
2004-06-02 15:52                                                     ` Linus Torvalds
2004-06-02 16:17                                                       ` Jörn Engel
2004-06-02 16:25                                                         ` Linus Torvalds
2004-06-02 17:17                                                           ` Jörn Engel
2004-06-02 17:32                                                             ` Greg KH
2004-06-02 17:46                                                               ` Jörn Engel
2004-06-02 14:35                                           ` Davide Libenzi
2004-06-02 18:20                                             ` Jörn Engel
2004-06-02 18:37                                               ` Davide Libenzi
2004-06-02 18:58                                                 ` Jörn Engel
2004-06-02 19:33                                                   ` Valdis.Kletnieks
2004-06-02 19:37                                                   ` viro
2004-06-02 19:45                                                     ` Jörn Engel
2004-06-02 19:59                                                       ` viro
2004-06-03  6:55                                                         ` Jörn Engel
2004-06-02 19:55                                                     ` Valdis.Kletnieks
2004-06-02 23:20                                                   ` Davide Libenzi
2004-06-03  7:29                                                     ` Jörn Engel
2004-06-01 12:39                                 ` viro
2004-06-01 13:26                                   ` Jörn Engel
2004-06-07 18:14                         ` 4k stacks in 2.6 Timothy Miller
2004-06-08  6:26                           ` Arjan van de Ven
2004-06-08  8:45                             ` Jörn Engel
2004-05-26 18:12                     ` David S. Miller
2004-05-26 19:02                       ` Matt Mackall
2004-05-26 19:25                         ` Dave Jones
2004-05-25 21:16               ` 4g/4g for 2.6.6 Andrew Morton
2004-05-25 21:48                 ` Ingo Molnar
2004-05-25 22:09                   ` David S. Miller
2004-05-25 22:20                     ` Ingo Molnar
2004-05-25 23:10                       ` David S. Miller
2004-05-25 21:04             ` Bill Davidsen
2004-05-24  1:33 ` Martin J. Bligh
2004-05-24  1:38   ` Phy Prabab
     [not found] <1ZQpn-1Rx-1@gated-at.bofh.it>
     [not found] ` <1ZQz8-1Yh-15@gated-at.bofh.it>
     [not found]   ` <1ZRFf-2Vt-3@gated-at.bofh.it>
     [not found]     ` <203Zu-4aT-15@gated-at.bofh.it>
2004-05-26 13:57       ` 4k stacks in 2.6 Andi Kleen
2004-05-26 18:17         ` hch
2004-05-26 18:24           ` Andi Kleen
2004-05-26 20:39         ` Zwane Mwaikambo
     [not found]       ` <206b3-5WN-33@gated-at.bofh.it>
     [not found]         ` <20baw-1Lz-15@gated-at.bofh.it>
2004-05-26 19:32           ` Andi Kleen
2004-05-27 11:27             ` Jörn Engel
2004-05-27 13:49               ` Andrea Arcangeli
2004-05-27 14:15                 ` Jörn Engel
2004-05-27 14:49                   ` Andrea Arcangeli
2004-05-27 14:59                     ` Jörn Engel
2004-05-27 15:08                       ` Keith Owens
2004-05-27 15:21                         ` Jörn Engel
2004-05-27 15:34                           ` Arjan van de Ven
2004-05-27 15:46                             ` Jörn Engel
2004-06-01  5:25                             ` Jörn Engel
  -- strict thread matches above, loose matches on Subject: below --
2004-05-26 15:17 Albert Cahalan

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