From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Oleg Nesterov <oleg@tv-sign.ru>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Ingo Molnar <mingo@elte.hu>,
Christoph Hellwig <hch@infradead.org>,
Andrew Morton <akpm@osdl.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/7] barrier: a scalable synchonisation barrier
Date: Sat, 3 Feb 2007 21:46:03 -0800 [thread overview]
Message-ID: <20070204054603.GI5647@linux.vnet.ibm.com> (raw)
In-Reply-To: <Pine.LNX.4.44L0.0702032220560.17500-100000@netrider.rowland.org>
On Sat, Feb 03, 2007 at 10:24:04PM -0500, Alan Stern wrote:
> On Sat, 3 Feb 2007, Paul E. McKenney wrote:
>
> > > And another note: this all assumes that STORE-MB-LOAD works "correctly", yes?
> > > We have other code which relies on that, should not be a problem.
> >
> > We have been working with Doug Lea of SUNY Oswego, Sebatian Burckhardt of
> > University of Pennsylvania, and Vijay Saraswat of IBM Research towards
> > a "universal memory model" that accommodates all machines. Currently,
> > it does in fact handle store-mb-load the way we all want, thankfully!
>
> We should add that many places in the kernel do depend on proper behavior
> for this data access pattern. So whatever "universal memory model" we end
> up with, it had better handle the pattern correctly if Linux is to support
> it.
Agreed!
> It's interesting to note, however, that this does exclude simple MESI.
Yep! And also a number of compiler optimizations, as it turns out. ;-)
There is a tension between nice-to-software memory-barrier properties
on the one hand and easily understood code on the other. But I guess
that this is true of pretty much any software tool.
Thanx, Paul
next prev parent reply other threads:[~2007-02-04 5:46 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-01-28 11:51 [PATCH 0/7] breaking the global file_list_lock Peter Zijlstra
2007-01-28 11:51 ` [PATCH 1/7] lockdep: lock_set_subclass - reset a held locks subclass Peter Zijlstra
2007-01-28 11:51 ` [PATCH 3/7] barrier: a scalable synchonisation barrier Peter Zijlstra
2007-01-28 14:39 ` Christoph Hellwig
2007-01-28 15:24 ` Ingo Molnar
2007-01-28 15:34 ` Christoph Hellwig
2007-01-31 19:12 ` Paul E. McKenney
2007-01-31 21:13 ` Oleg Nesterov
2007-01-31 21:30 ` Oleg Nesterov
2007-01-31 21:48 ` Peter Zijlstra
2007-01-31 23:32 ` Paul E. McKenney
2007-02-01 0:03 ` Peter Zijlstra
2007-02-01 0:48 ` Paul E. McKenney
2007-02-01 16:00 ` Oleg Nesterov
2007-02-01 21:38 ` Paul E. McKenney
2007-02-02 11:56 ` Oleg Nesterov
2007-02-02 12:01 ` Peter Zijlstra
2007-02-02 17:13 ` Paul E. McKenney
2007-02-03 16:38 ` Oleg Nesterov
2007-02-04 0:23 ` Paul E. McKenney
2007-02-04 3:24 ` Alan Stern
2007-02-04 5:46 ` Paul E. McKenney [this message]
2007-01-28 11:51 ` [PATCH 4/7] fs: break the file_list_lock for sb->s_files Peter Zijlstra
2007-01-28 14:43 ` Christoph Hellwig
2007-01-28 15:21 ` Ingo Molnar
2007-01-28 15:30 ` Christoph Hellwig
2007-01-28 15:32 ` Peter Zijlstra
2007-01-28 15:36 ` Christoph Hellwig
2007-01-28 15:44 ` Ingo Molnar
2007-01-28 16:25 ` Bill Huey
2007-01-28 11:51 ` [PATCH 5/7] fs: restore previous sb->s_files iteration semantics Peter Zijlstra
2007-01-28 11:51 ` [PATCH 6/7] schedule_on_each_cpu_wq() Peter Zijlstra
2007-01-28 11:51 ` [PATCH 7/7] fs: fixup filevec_add_drain_all Peter Zijlstra
2007-01-28 12:16 ` [PATCH 8/7] fs: free_write_pipe() fix Peter Zijlstra
2007-01-28 14:43 ` [PATCH 0/7] breaking the global file_list_lock Christoph Hellwig
2007-01-28 15:11 ` Christoph Hellwig
2007-01-28 15:29 ` Peter Zijlstra
2007-01-28 15:33 ` Christoph Hellwig
2007-01-29 13:32 ` Stephen Smalley
2007-01-29 18:02 ` Christoph Hellwig
2007-01-28 15:24 ` Ingo Molnar
2007-01-28 16:52 ` Martin J. Bligh
2007-01-28 17:04 ` lockmeter Christoph Hellwig
2007-01-28 17:38 ` lockmeter Martin J. Bligh
2007-01-28 18:01 ` lockmeter Bill Huey
2007-01-28 19:26 ` lockmeter Ingo Molnar
2007-01-28 21:17 ` lockmeter Ingo Molnar
2007-01-29 5:27 ` lockmeter Bill Huey
2007-01-29 10:26 ` lockmeter Bill Huey
2007-01-29 1:08 ` lockmeter Arjan van de Ven
2007-01-29 1:12 ` lockmeter Martin J. Bligh
2007-01-28 18:41 ` [PATCH 0/7] breaking the global file_list_lock Ingo Molnar
2007-01-28 20:38 ` Christoph Hellwig
2007-01-28 21:05 ` Ingo Molnar
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