From: Andrew Morton <akpm@digeo.com>
To: Roland McGrath <roland@redhat.com>
Cc: torvalds@transmeta.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] i386 uaccess to fixmap pages
Date: Fri, 9 May 2003 02:19:21 -0700 [thread overview]
Message-ID: <20030509021921.166f82fc.akpm@digeo.com> (raw)
In-Reply-To: <200305090855.h498t4b12921@magilla.sf.frob.com>
Roland McGrath <roland@redhat.com> wrote:
>
> > This doesn't apply against Linus's current tree.
>
> Ok. I don't use bk, but I can update relative to the latest snapshot on
> kernel.org.
Yup. The best place usually is the first link here:
http://www.kernel.org/pub/linux/kernel/v2.5/testing/cset/
the "Gzipped full patch".
> > Your patch increases the kernel text by nearly 1%. That's rather a lot for
> > what is a fairly esoteric feature.
>
> Agreed. I hadn't thought about that angle. I am open to suggestions on
> other ways to make it work.
>
> > Would it be possible to avoid this by just taking the fault and fixing
> > things up in the exception handler?
>
> There is no fault that would be taken.
oop, very true.
Nasty. Maybe the best approach is to mostly uninline the access_ok()
check. Do the check for constant-sized small copies first, so those guys
still do the access_ok() check inline; uninline the rest.
It'll hurt the microbenchmarks (again), but it's a general article of faith
that keeping the kernel's cache footprint small is a net win...
Let me think about that for a bit.
> > For some reason the patch causes gcc-2.95.3 to choke over the
>
> You got me. That version of gcc has many, many bugs and is long obsolete.
> Random meaningless perturbations of the code might change its behavior.
Turns out that it only happens with `-O1'. -O2 is OK. I use -O1 because
it is faster. I use gcc-2.95.3 because gcc-3.x is unacceptably slow.
next prev parent reply other threads:[~2003-05-09 9:06 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-05-09 2:03 [PATCH] i386 uaccess to fixmap pages Roland McGrath
2003-05-09 4:31 ` Andrew Morton
2003-05-09 8:55 ` Roland McGrath
2003-05-09 9:19 ` Andrew Morton [this message]
2003-05-09 9:40 ` Roland McGrath
2003-05-09 10:43 ` Roland McGrath
2003-05-09 11:42 ` Dave Jones
2003-05-09 11:55 ` Alan Cox
2003-05-09 12:40 ` Jamie Lokier
2003-05-09 16:06 ` Linus Torvalds
2003-05-09 16:38 ` Dave Hansen
2003-05-09 15:55 ` Martin J. Bligh
2003-05-09 18:20 ` William Lee Irwin III
2003-05-09 16:48 ` Linus Torvalds
2003-05-09 17:16 ` Dave Hansen
2003-05-10 3:26 ` H. Peter Anvin
2003-05-10 15:31 ` Jamie Lokier
2003-05-10 17:23 ` Ulrich Drepper
2003-05-10 19:23 ` H. Peter Anvin
2003-05-10 20:52 ` Jamie Lokier
2003-05-09 17:28 Chuck Ebbert
2003-05-09 17:49 ` Linus Torvalds
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=20030509021921.166f82fc.akpm@digeo.com \
--to=akpm@digeo.com \
--cc=linux-kernel@vger.kernel.org \
--cc=roland@redhat.com \
--cc=torvalds@transmeta.com \
/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).