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From: torvalds@transmeta.com (Linus Torvalds)
To: linux-kernel@vger.kernel.org
Subject: Re: /proc/<n>/maps getting _VERY_ long
Date: Mon, 6 Aug 2001 04:26:50 +0000 (UTC)	[thread overview]
Message-ID: <9kl6aa$87l$1@penguin.transmeta.com> (raw)
In-Reply-To: <20010805171202.A20716@weta.f00f.org> <20010805204143.A18899@alcove.wittsend.com> <9kkq9k$829$1@penguin.transmeta.com> <9kkr7r$mov$1@cesium.transmeta.com>

In article <9kkr7r$mov$1@cesium.transmeta.com>,
H. Peter Anvin <hpa@zytor.com> wrote:
>
>Do you count applications which selectively mprotect()'s memory (to
>trap SIGSEGV and maintain coherency with on-disk data structures) as
>"broken applications"?
>
>Such applications *can* use large amounts of mprotect()'s.

Note that such applications tend to not get any advantage from merging -
it does in fact only slow things down (because then the next mprotect
just has to split the thing again).

No, they aren't broken, but they should know that the use of lots of
small memory segments (even if it is a design goal) can and will slow
down page faulting, and use more memory for MM management for example. 

Linux does have a log(n) vma lookup, so the slowdown isn't huge.

		Linus


  reply	other threads:[~2001-08-06  4:28 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2001-08-04 15:43 /proc/<n>/maps getting _VERY_ long Chris Wedgwood
2001-08-05  2:17 ` Rik van Riel
2001-08-05  5:12   ` Chris Wedgwood
2001-08-05 13:06     ` Alan Cox
2001-08-05 13:18       ` Chris Wedgwood
2001-08-05 23:07       ` Jakob Østergaard
2001-08-05 23:41       ` Linus Torvalds
2001-08-06  0:41         ` Michael H. Warfield
2001-08-06  1:01           ` Linus Torvalds
2001-08-06  1:17             ` H. Peter Anvin
2001-08-06  4:26               ` Linus Torvalds [this message]
2001-08-06  6:30                 ` H. Peter Anvin
2001-08-06 18:41                 ` Jamie Lokier
2001-08-10 21:55                   ` Linus Torvalds
2001-08-10 22:00                     ` H. Peter Anvin
2001-08-10 23:03                       ` Nicolas Pitre
2001-08-10 23:26                       ` Linus Torvalds
2001-08-10 23:55                         ` Rik van Riel
2001-08-11  1:04                     ` Pavel Machek
2001-08-06 11:52               ` Alan Cox
2001-08-06 12:23                 ` Chris Wedgwood
2001-08-06 13:17                   ` Alan Cox
2001-08-06 13:55                     ` Chris Wedgwood
2001-08-06  9:43         ` [LONGish] Brief analysis of VMAs (was: /proc/<n>/maps getting _VERY_ long) Chris Wedgwood
2001-08-05  6:44 /proc/<n>/maps getting _VERY_ long David Luyer
2001-08-05  7:21 ` Anders Eriksson

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