From: Davide Libenzi <davidel@xmailserver.org>
To: "Boehm, Hans" <hans_boehm@hp.com>
Cc: "'Arjan van de Ven'" <arjanv@redhat.com>,
Hans Boehm <Hans.Boehm@hp.com>,
"MOSBERGER, DAVID (HP-PaloAlto,unix3)" <davidm@hpl.hp.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-ia64@linuxia64.org
Subject: RE: [Linux-ia64] Re: web page on O(1) scheduler
Date: Sat, 24 May 2003 07:43:12 -0700 (PDT) [thread overview]
Message-ID: <Pine.LNX.4.55.0305240716230.3978@bigblue.dev.mcafeelabs.com> (raw)
In-Reply-To: <Pine.LNX.4.55.0305232225010.3538@bigblue.dev.mcafeelabs.com>
On Fri, 23 May 2003, Davide Libenzi wrote:
> You need a write memory barrier even on the unlock. Consider this :
>
> spinlock = 1;
> ...
> protected_resource = NEWVAL;
> spinlock = 0;
>
> ( where spinlock = 0/1 strip down, but do not lose the concept, the lock
> operation ). If a CPU reorder those writes, another CPU might see the lock
> drop before the protected resource assignment. And this is usually bad
> for obvious reasons.
David made me notice about a brain misfire here. You need protection even
for loads crossing the unlock. For the same obvious reasons :) Yes, a
realease barrier will be sufficent for ia64, while you'll need an mfence
on P4.
- Davide
next prev parent reply other threads:[~2003-05-24 14:30 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-05-24 0:53 Boehm, Hans
2003-05-24 5:38 ` Davide Libenzi
2003-05-24 14:43 ` Davide Libenzi [this message]
-- strict thread matches above, loose matches on Subject: below --
2003-05-24 0:10 Boehm, Hans
2003-05-24 0:20 ` Davide Libenzi
2003-05-23 17:48 Boehm, Hans
2003-05-23 18:04 ` Davide Libenzi
2003-05-21 6:49 David Mosberger
2003-05-21 9:01 ` Arjan van de Ven
2003-05-21 10:40 ` [Linux-ia64] " Duraid Madina
2003-05-21 10:43 ` Christoph Hellwig
2003-05-21 13:12 ` Arjan van de Ven
2003-05-21 13:51 ` Olivier Galibert
2003-05-28 22:12 ` Bill Davidsen
[not found] ` <Pine.LNX.3.96.1030528180909.21414B-100000@gatekeeper.tmr.c om>
2003-05-29 5:59 ` Mike Galbraith
2003-06-02 8:05 ` Ingo Molnar
2003-06-04 4:07 ` Bill Davidsen
[not found] ` <Pine.LNX.4.44.0306020949520.3375-100000@localhost.localdom ain>
2003-06-02 13:51 ` Mike Galbraith
2003-06-04 3:52 ` Bill Davidsen
2003-06-04 4:55 ` David Schwartz
[not found] ` <Pine.LNX.3.96.1030603234616.16495B-100000@gatekeeper.tmr.c om>
2003-06-04 7:13 ` Mike Galbraith
2003-06-04 15:30 ` Jan Harkes
2003-05-21 19:18 ` Duraid Madina
2003-05-21 20:03 ` Helge Hafting
2003-05-21 22:59 ` Alan Cox
2003-05-23 1:07 ` Hans Boehm
2003-05-23 8:30 ` Arjan van de Ven
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=Pine.LNX.4.55.0305240716230.3978@bigblue.dev.mcafeelabs.com \
--to=davidel@xmailserver.org \
--cc=Hans.Boehm@hp.com \
--cc=arjanv@redhat.com \
--cc=davidm@hpl.hp.com \
--cc=hans_boehm@hp.com \
--cc=linux-ia64@linuxia64.org \
--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
all inboxes | Powered by JetHome®