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From: Peter Zijlstra <peterz@infradead.org>
To: Stefan Richter <stefanr@s5r6.in-berlin.de>
Cc: jmerkey@wolfmountaingroup.com, linux-kernel@vger.kernel.org,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Nick Piggin <nickpiggin@yahoo.com.au>,
	Paul E McKenney <paulmck@linux.vnet.ibm.com>,
	David Howells <dhowells@redhat.com>
Subject: Re: [ANNOUNCE] mdb: Merkey's Linux Kernel Debugger 2.6.27-rc4	released
Date: Thu, 21 Aug 2008 13:02:48 +0200	[thread overview]
Message-ID: <1219316568.8651.107.camel@twins> (raw)
In-Reply-To: <48AD4A0B.8020805@s5r6.in-berlin.de>

On Thu, 2008-08-21 at 12:57 +0200, Stefan Richter wrote:
> Peter Zijlstra wrote:
> > On Wed, 2008-08-20 at 20:50 -0600, jmerkey@wolfmountaingroup.com wrote:
> > 
> >>  volatiles left in the code due to the previously stated
> >>  (and still present) severe breakage of the GNU compiler with SMP 
> >>  shared data.  most of the barrier() functions are just plain broken
> >>  and do not result in proper compiler behavior in this tree. 
> > 
> > Can you provide explicit detail?
> > 
> > By using barrier() the compiler should clobber all its memory and
> > registers therefore forcing a write/reload of the variable.
> 
> I hope Jeff didn't try mere barrier()s only.  smp_wmb() and smp_rmb()
> are the more relevant barrier variants for mdb, from what I remember
> when I last looked at it.

Sure, but volatile isn't a replacement for memory barriers.


  reply	other threads:[~2008-08-21 11:03 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-08-21  2:50 [ANNOUNCE] mdb: Merkey's Linux Kernel Debugger 2.6.27-rc4 released jmerkey
2008-08-21 10:07 ` Peter Zijlstra
2008-08-21 10:57   ` Stefan Richter
2008-08-21 11:02     ` Peter Zijlstra [this message]
2008-08-21 11:47       ` Paul E. McKenney
2008-08-21 12:03         ` Peter Zijlstra
2008-08-21 14:53           ` Paul E. McKenney
2008-08-21 14:58             ` jmerkey
2008-08-21 12:05         ` Stefan Richter
2008-08-21 12:26           ` jmerkey
     [not found]             ` <43593.166.70.238.46.1219321595.squirrel@webmail.wolfmountaingroup.com >
2008-08-21 12:35               ` jmerkey
2008-08-21 13:37             ` Nick Piggin
2008-08-21 14:09               ` Stefan Richter
2008-08-22  1:40                 ` Nick Piggin
2008-08-22  6:32                   ` Stefan Richter
2008-08-22 11:54                     ` jmerkey
2008-08-22 12:36                       ` Stefan Richter
2008-08-21 14:09               ` Peter Zijlstra
2008-08-21 14:30                 ` Paul E. McKenney
2008-08-21 14:14                   ` jmerkey
2008-08-21 14:48                   ` Peter Zijlstra
2008-08-21 16:21                 ` Avi Kivity
2008-08-21 21:06               ` Jeremy Fitzhardinge
2008-08-21 21:18                 ` Linus Torvalds
2008-08-21 21:21                   ` Jeremy Fitzhardinge
2008-08-24  4:25                   ` jmerkey
2008-08-26  8:26                     ` Andi Kleen
2008-08-27  1:49                       ` jmerkey
2008-08-22  1:37                 ` Nick Piggin
2008-08-21 14:02             ` Stefan Richter
2008-08-21 14:08               ` jmerkey
2008-08-21 15:22                 ` Stefan Richter
2008-08-21 15:02                   ` jmerkey
2008-08-21 15:57         ` Linus Torvalds
2008-08-21 16:18           ` Linus Torvalds
2008-08-21 16:48             ` Paul E. McKenney
2008-09-24  0:01               ` Paul E. McKenney
2008-08-21 16:43           ` Paul E. McKenney

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