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From: Alan Modra <amodra@bigpond.net.au>
To: Paul Mackerras <paulus@samba.org>
Cc: "David S. Miller" <davem@davemloft.net>,
	linux-arch@vger.kernel.org, linuxppc-dev@ozlabs.org,
	linux-kernel@vger.kernel.org, rth@twiddle.net
Subject: Re: [RFC/PATCH] Make powerpc64 use __thread for per-cpu variables
Date: Thu, 11 May 2006 10:34:38 +0930	[thread overview]
Message-ID: <20060511010438.GE24458@bubble.grove.modra.org> (raw)
In-Reply-To: <17506.21908.857189.645889@cargo.ozlabs.ibm.com>

On Thu, May 11, 2006 at 07:05:24AM +1000, Paul Mackerras wrote:
> No, Richard has a point, it's not the value that is the concern, it's
> the address, which gcc could assume is still valid after a barrier.
> Drat.

That may never happen, at least with a compiler that knows how to
optimise away the addi.  You're using -mtls-size=16 so all your accesses
should look like

	lwz rn,per_cpu_var@tprel(13)

gcc shouldn't think there is any reason to cache the address.

-- 
Alan Modra
IBM OzLabs - Linux Technology Centre

  parent reply	other threads:[~2006-05-11  1:04 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-05-10  4:03 [RFC/PATCH] Make powerpc64 use __thread for per-cpu variables Paul Mackerras
2006-05-10  5:16 ` Olof Johansson
2006-05-10  5:35   ` Alan Modra
2006-05-10  6:22   ` David S. Miller
2006-05-10  6:29   ` Paul Mackerras
2006-05-10  6:39     ` David S. Miller
2006-05-10  7:21       ` Benjamin Herrenschmidt
2006-05-10  7:41       ` Paul Mackerras
2006-05-10 10:14       ` David Howells
2006-05-10 15:47 ` Richard Henderson
2006-05-10 18:04   ` Steven Rostedt
2006-05-10 19:40   ` David S. Miller
2006-05-10 21:05     ` Paul Mackerras
2006-05-10 22:25       ` David S. Miller
2006-05-10 23:17       ` Segher Boessenkool
2006-05-11  0:22         ` Richard Henderson
2006-05-11 23:41           ` Segher Boessenkool
2006-05-11  1:04       ` Alan Modra [this message]
2006-05-11  1:21         ` Paul Mackerras
2006-05-11  2:01           ` Alan Modra
2006-05-11 23:42           ` Segher Boessenkool
2006-05-10 23:05   ` Paul Mackerras
2006-05-10 23:44     ` Paul Mackerras
2006-05-11  0:11       ` David S. Miller
2006-05-18 23:50         ` Paul Mackerras

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