From: Nick Piggin <nickpiggin@yahoo.com.au>
To: "Chen, Kenneth W" <kenneth.w.chen@intel.com>
Cc: "'Christoph Lameter'" <clameter@sgi.com>,
Zoltan Menyhart <Zoltan.Menyhart@bull.net>,
"Boehm, Hans" <hans.boehm@hp.com>,
"Grundler, Grant G" <grant.grundler@hp.com>,
akpm@osdl.org, linux-kernel@vger.kernel.org,
linux-ia64@vger.kernel.org
Subject: Re: Synchronizing Bit operations V2
Date: Fri, 31 Mar 2006 17:34:48 +1000 [thread overview]
Message-ID: <442CDB98.80803@yahoo.com.au> (raw)
In-Reply-To: <200603310614.k2V6Ehg30012@unix-os.sc.intel.com>
Chen, Kenneth W wrote:
> Nick Piggin wrote on Thursday, March 30, 2006 6:53 PM
>>The memory ordering that above combination should produce is a
>>Linux style smp_mb before the clear_bit. Not a release.
>
>
> Whoever designed the smp_mb_before/after_* clearly understand the
> difference between a bidirectional smp_mb() and a one-way memory
> ordering. If smp_mb_before/after are equivalent to smp_mb, what's
> the point of introducing another interface?
>
They are not. They provide equivalent barrier when performed
before/after a clear_bit, there is a big difference.
You guys (ia64) are the ones who want to introduce a new
interface, because you think conforming to the kernel's current
interfaces will be too costly. I simply suggested a way you
could do this that would have a chance of being merged.
If you want to change the semantics of smp_mb__*, then good
luck auditing all that well documented code that uses it.
I just happen to think your best bet is to stick with the
obvious full barrier semantics (which is what other
architectures, eg powerpc do), and introduce something new
if you want more performance.
--
SUSE Labs, Novell Inc.
Send instant messages to your online friends http://au.messenger.yahoo.com
next prev parent reply other threads:[~2006-03-31 16:20 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-03-30 21:02 Bit operations with the ability to specify a synchronization mode Christoph Lameter
2006-03-31 0:18 ` Synchronizing Bit operations V2 Christoph Lameter
2006-03-31 0:39 ` Chen, Kenneth W
2006-03-31 0:42 ` Christoph Lameter
2006-03-31 0:53 ` Chen, Kenneth W
2006-03-31 0:55 ` Christoph Lameter
2006-03-31 1:04 ` Chen, Kenneth W
2006-03-31 1:13 ` Christoph Lameter
2006-03-31 1:29 ` Chen, Kenneth W
2006-03-31 1:37 ` Christoph Lameter
2006-03-31 2:35 ` Chen, Kenneth W
2006-03-31 2:37 ` Christoph Lameter
2006-03-31 2:45 ` Chen, Kenneth W
2006-03-31 2:53 ` Nick Piggin
2006-03-31 6:15 ` Chen, Kenneth W
2006-03-31 7:34 ` Nick Piggin [this message]
2006-03-31 18:57 ` Chen, Kenneth W
2006-03-31 19:41 ` Chen, Kenneth W
2006-03-31 21:15 ` Christoph Lameter
2006-03-31 21:24 ` Chen, Kenneth W
2006-03-31 21:28 ` Christoph Lameter
2006-04-01 2:16 ` Nick Piggin
2006-03-31 3:01 ` Christoph Lameter
2006-03-31 3:10 ` Chen, Kenneth W
2006-03-31 3:12 ` Christoph Lameter
2006-03-31 3:14 ` Chen, Kenneth W
2006-03-31 3:20 ` Christoph Lameter
2006-03-31 3:37 ` Chen, Kenneth W
2006-03-31 3:17 ` Chen, Kenneth W
2006-03-31 3:23 ` Chen, Kenneth W
2006-03-31 0:45 ` Christoph Lameter
2006-03-31 0:50 ` Chen, Kenneth W
2006-03-31 0:51 ` Christoph Lameter
2006-03-31 0:59 ` Chen, Kenneth W
2006-03-31 1:09 ` Christoph Lameter
2006-03-31 1:13 ` Chen, Kenneth W
2006-03-31 0:42 ` David Mosberger-Tang
2006-03-31 0:49 ` Christoph Lameter
2006-03-31 6:10 ` Chris Wright
2006-03-31 0:44 ` Nick Piggin
2006-03-31 3:28 ` Christoph Lameter
2006-03-31 4:12 ` Nick Piggin
2006-03-31 17:43 ` Christoph Lameter
2006-04-01 2:56 ` Nick Piggin
2006-03-31 13:28 ` Andi Kleen
2006-03-31 16:22 ` Hans Boehm
2006-03-31 16:37 ` Andi Kleen
2006-03-31 17:46 ` Christoph Lameter
2006-03-31 17:45 ` Christoph Lameter
2006-03-31 17:48 ` Andi Kleen
2006-03-31 17:56 ` Christoph Lameter
2006-04-02 7:54 ` Russell King
-- strict thread matches above, loose matches on Subject: below --
2006-03-31 0:56 Luck, Tony
2006-03-31 0:58 ` Christoph Lameter
2006-04-02 7:59 ` Russell King
2006-03-31 1:33 linux
2006-03-31 1:40 ` Christoph Lameter
2006-03-31 2:51 Chen, Kenneth W
2006-03-31 2:55 ` Christoph Lameter
2006-03-31 3:02 ` Chen, Kenneth W
2006-03-31 3:08 ` Christoph Lameter
2006-03-31 3:11 ` Chen, Kenneth W
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=442CDB98.80803@yahoo.com.au \
--to=nickpiggin@yahoo.com.au \
--cc=Zoltan.Menyhart@bull.net \
--cc=akpm@osdl.org \
--cc=clameter@sgi.com \
--cc=grant.grundler@hp.com \
--cc=hans.boehm@hp.com \
--cc=kenneth.w.chen@intel.com \
--cc=linux-ia64@vger.kernel.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