From: "Leonidas ." <leonidas137@gmail.com>
To: Michael Schnell <mschnell@lumino.de>
Cc: Stefan Richter <stefanr@s5r6.in-berlin.de>,
Noah Watkins <noah@noahdesu.com>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: Difference between atomic operations and memory barriers
Date: Tue, 27 Oct 2009 03:23:12 -0700 [thread overview]
Message-ID: <f22d86810910270323m6e004576ya4da96afc02e3d07@mail.gmail.com> (raw)
In-Reply-To: <4AE6C998.9040405@lumino.de>
On Tue, Oct 27, 2009 at 3:21 AM, Michael Schnell <mschnell@lumino.de> wrote:
> Leonidas . wrote:
>>
>> any_t *ptr = something;
>>
>> is always atomic even on SMPs without using locks, barriers then my
>> doubt is cleared. Thanks.
>
> I assume that this only holds if the pointer (not the thing it points
> to) is denoted as volatile.
>
> -Michael
>
I dont think so, volatile would only ensure no caching, so some cpus
might see the cached
pointer (this is where you would want to use barriers), but pointer
assignment would still be atomic.
-Leo.
next prev parent reply other threads:[~2009-10-27 10:23 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-26 17:19 Leonidas .
[not found] ` <7ADB5FD7-9C97-4987-BC20-997258B25FD2@noahdesu.com>
2009-10-26 18:22 ` Leonidas .
2009-10-26 18:54 ` Chris Friesen
2009-10-26 19:00 ` Leonidas .
2009-10-26 19:07 ` Noah Watkins
2009-10-26 19:34 ` Stefan Richter
2009-10-26 19:42 ` Noah Watkins
2009-10-27 11:51 ` Valdis.Kletnieks
2009-10-28 10:00 ` Boaz Harrosh
2009-10-28 13:26 ` Valdis.Kletnieks
2009-10-26 19:00 ` Stefan Richter
2009-10-26 19:05 ` Leonidas .
2009-10-27 10:21 ` Michael Schnell
2009-10-27 10:23 ` Leonidas . [this message]
2009-10-27 11:01 ` Michael Schnell
2009-10-27 14:57 ` Stefan Richter
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=f22d86810910270323m6e004576ya4da96afc02e3d07@mail.gmail.com \
--to=leonidas137@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mschnell@lumino.de \
--cc=noah@noahdesu.com \
--cc=stefanr@s5r6.in-berlin.de \
/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®