From: "H. Peter Anvin" <hpa@zytor.com>
To: linux-kernel@vger.kernel.org
Subject: Re: /proc/<n>/maps getting _VERY_ long
Date: 5 Aug 2001 23:30:44 -0700 [thread overview]
Message-ID: <9kldik$nap$1@cesium.transmeta.com> (raw)
In-Reply-To: <20010805171202.A20716@weta.f00f.org> <9kkq9k$829$1@penguin.transmeta.com> <9kkr7r$mov$1@cesium.transmeta.com> <9kl6aa$87l$1@penguin.transmeta.com>
Followup to: <9kl6aa$87l$1@penguin.transmeta.com>
By author: torvalds@transmeta.com (Linus Torvalds)
In newsgroup: linux.dev.kernel
>
> In article <9kkr7r$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).
>
Unless you're doing a sequential access in the data space, for example
while accessing a large object. If a single large object (usually
called a BLOB) covers N pages, and is accessed in its entirety, you
will typically have N pagefaults, each of which bring/unprotect the
page and then mprotect() it accordingly. Those could all be merged
back into a single vma.
Now, I don't know how frequently this actually happens, but I do think
it is at least a possibility.
-hpa
--
<hpa@transmeta.com> at work, <hpa@zytor.com> in private!
"Unix gives you enough rope to shoot yourself in the foot."
http://www.zytor.com/~hpa/puzzle.txt <amsp@zytor.com>
next prev parent reply other threads:[~2001-08-06 6:31 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
2001-08-06 6:30 ` H. Peter Anvin [this message]
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='9kldik$nap$1@cesium.transmeta.com' \
--to=hpa@zytor.com \
--cc=linux-kernel@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).