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From: linas@austin.ibm.com (Linas Vepstas)
To: Scott Wood <scottwood@freescale.com>
Cc: Kumar Gala <galak@kernel.crashing.org>,
	netdev@vger.kernel.org, jgarzik@pobox.com,
	linuxppc-dev@ozlabs.org
Subject: Re: [PATCH v2] gianfar: Add I/O barriers when touching buffer descriptor ownership.
Date: Fri, 4 May 2007 17:13:09 -0500	[thread overview]
Message-ID: <20070504221309.GR6193@austin.ibm.com> (raw)
In-Reply-To: <4638F734.2040809@freescale.com>

On Wed, May 02, 2007 at 03:40:20PM -0500, Scott Wood wrote:
> 
> Well, Segher doesn't want me to use iobarrier (because it's not I/O). 
> Andy doesn't want me to use wmb() (because it's sync).  I don't think 
> something like gfar_wmb() would be appropriate.  So the remaining 
> options are either eieio(), 

? Just curious... the original intent of eieio was to order I/O, 
such as MMIO; it has no effect on memory that isn't marked 
cache-inhibited or write-trhough or guarded. Has this changed?
I guess I haven't kept up with the times ... is eieio now
being used to provide some other kind of barrier?
Is eieio providing some sort of SMP synchronization side-effect?

Point being: if Segher doesn't let you "use iobarrier (because 
it's not I/O)", then I don't understand why eieio would work (since
that's for io only).  

--linas

  parent reply	other threads:[~2007-05-04 22:13 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-05-02 19:57 [PATCH v2] gianfar: Add I/O barriers when touching buffer descriptor ownership Scott Wood
2007-05-02 20:09 ` Kumar Gala
2007-05-02 20:12   ` Scott Wood
2007-05-02 20:20     ` Kumar Gala
2007-05-02 20:40       ` Scott Wood
2007-05-02 21:23         ` Kumar Gala
2007-05-02 21:30           ` Scott Wood
2007-05-03  2:10             ` Kumar Gala
2007-05-03 16:00               ` Scott Wood
2007-05-03 16:38                 ` Segher Boessenkool
2007-05-02 23:42         ` Segher Boessenkool
2007-05-04 22:13         ` Linas Vepstas [this message]
2007-05-04 23:24           ` Olof Johansson
2007-05-05  0:41           ` Segher Boessenkool

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