From: "Chen, Kenneth W" <kenneth.w.chen@intel.com>
To: 'Nick Piggin' <nickpiggin@yahoo.com.au>
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 19:41:11 +0000 [thread overview]
Message-ID: <200603311940.k2VJeRg05420@unix-os.sc.intel.com> (raw)
In-Reply-To: <442CDB98.80803@yahoo.com.au>
In-Reply-To: <Pine.LNX.4.64.0603301615540.2023@schroedinger.engr.sgi.com>
Nick Piggin wrote on Thursday, March 30, 2006 11:35 PM
> > 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.
Just to give another blunt brutal example, what is said here is equivalent
to say kernel requires:
<end of critical section>
smp_mb_before_spin_unlock
spin_unlock
Because it is undesirable to have spin_unlock to leak into the critical
Section and allow critical section to leak after spin_unlock. This is
just plain brain dead.
next prev parent reply other threads:[~2006-03-31 19:41 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 0:45 ` Christoph Lameter
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 0:50 ` Chen, Kenneth W
2006-03-31 0:51 ` Christoph Lameter
2006-03-31 0:53 ` Chen, Kenneth W
2006-03-31 0:55 ` Christoph Lameter
2006-03-31 0:56 ` Luck, Tony
2006-03-31 0:58 ` Christoph Lameter
2006-04-02 7:59 ` Russell King
2006-03-31 0:59 ` Chen, Kenneth W
2006-03-31 1:09 ` Christoph Lameter
2006-03-31 1:04 ` Chen, Kenneth W
2006-03-31 1:13 ` Christoph Lameter
2006-03-31 1:13 ` Chen, Kenneth W
2006-03-31 1:29 ` Chen, Kenneth W
2006-03-31 1:37 ` Christoph Lameter
2006-03-31 1:33 ` linux
2006-03-31 1:40 ` 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 3:01 ` 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 3:10 ` Chen, Kenneth W
2006-03-31 3:12 ` Christoph Lameter
2006-03-31 3:11 ` Chen, Kenneth W
2006-03-31 3:14 ` Chen, Kenneth W
2006-03-31 3:20 ` Christoph Lameter
2006-03-31 3:17 ` Chen, Kenneth W
2006-03-31 3:23 ` Chen, Kenneth W
2006-03-31 3:37 ` Chen, Kenneth W
2006-03-31 6:15 ` Chen, Kenneth W
2006-03-31 7:34 ` 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
2006-03-31 18:57 ` Chen, Kenneth W
2006-03-31 19:41 ` Chen, Kenneth W [this message]
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
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