From: "H. Peter Anvin" <hpa@zytor.com>
To: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jakub Jelinek <jakub@redhat.com>,
One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>,
Tony Luck <tony.luck@intel.com>,
linux-ia64@vger.kernel.org,
Peter Hurley <peter@hurleysoftware.com>,
Mikael Pettersson <mikpelinux@gmail.com>,
Oleg Nesterov <oleg@redhat.com>,
linux-kernel@vger.kernel.org, Paul Mackerras <paulus@samba.org>,
linux-arch@vger.kernel.org, paulmck@linux.vnet.ibm.com,
linuxppc-dev@lists.ozlabs.org, Miroslav Franc <mfranc@redhat.com>,
Richard Henderson <rth@twiddle.net>
Subject: Re: bit fields && data tearing
Date: Mon, 08 Sep 2014 12:12:50 -0700 [thread overview]
Message-ID: <540DFFB2.4000509@zytor.com> (raw)
In-Reply-To: <1410203369.2027.56.camel@jarvis.lan>
On 09/08/2014 12:09 PM, James Bottomley wrote:
>
> Um, I think you need to re-read the thread; that's not what I said at
> all. It's even written lower down: "PA can't do atomic bit sets (no
> atomic RMW except the ldcw operation) it can do atomic writes to
> fundamental sizes (byte, short, int, long) provided gcc emits the
> correct primitive". The original question was whether atomicity
> required native bus width access, which we currently assume, so there's
> no extant problem.
>
The issue at hand was whether or not partially overlapped (but natually
aligned) writes can pass each other. *This* is the aggressive
relaxation to which I am referring.
I would guess that that is a very unusual constraint.
-hpa
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WARNING: multiple messages have this Message-ID (diff)
From: "H. Peter Anvin" <hpa@zytor.com>
To: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: paulmck@linux.vnet.ibm.com,
Peter Hurley <peter@hurleysoftware.com>,
One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>,
Jakub Jelinek <jakub@redhat.com>,
Mikael Pettersson <mikpelinux@gmail.com>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Richard Henderson <rth@twiddle.net>,
Oleg Nesterov <oleg@redhat.com>,
Miroslav Franc <mfranc@redhat.com>,
Paul Mackerras <paulus@samba.org>,
linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
linux-arch@vger.kernel.org, Tony Luck <tony.luck@intel.com>,
linux-ia64@vger.kernel.org
Subject: Re: bit fields && data tearing
Date: Mon, 08 Sep 2014 12:12:50 -0700 [thread overview]
Message-ID: <540DFFB2.4000509@zytor.com> (raw)
Message-ID: <20140908191250.AwYsxcFqdzgIxTBwLyaXSRLRcujxIaZ7G97BSx0ZDLA@z> (raw)
In-Reply-To: <1410203369.2027.56.camel@jarvis.lan>
On 09/08/2014 12:09 PM, James Bottomley wrote:
>
> Um, I think you need to re-read the thread; that's not what I said at
> all. It's even written lower down: "PA can't do atomic bit sets (no
> atomic RMW except the ldcw operation) it can do atomic writes to
> fundamental sizes (byte, short, int, long) provided gcc emits the
> correct primitive". The original question was whether atomicity
> required native bus width access, which we currently assume, so there's
> no extant problem.
>
The issue at hand was whether or not partially overlapped (but natually
aligned) writes can pass each other. *This* is the aggressive
relaxation to which I am referring.
I would guess that that is a very unusual constraint.
-hpa
next prev parent reply other threads:[~2014-09-08 19:12 UTC|newest]
Thread overview: 164+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20140712181328.GA8738@redhat.com>
2014-09-03 22:51 ` bit fields && data tearing Peter Hurley
2014-09-03 22:51 ` Peter Hurley
2014-09-03 23:11 ` Benjamin Herrenschmidt
2014-09-03 23:11 ` Benjamin Herrenschmidt
2014-09-04 8:43 ` David Laight
2014-09-04 9:52 ` Benjamin Herrenschmidt
2014-09-04 22:14 ` H. Peter Anvin
2014-09-04 22:14 ` H. Peter Anvin
2014-09-05 0:59 ` Peter Hurley
2014-09-05 0:59 ` Peter Hurley
2014-09-05 2:08 ` H. Peter Anvin
2014-09-05 2:08 ` H. Peter Anvin
2014-09-05 8:16 ` Michael Cree
2014-09-05 8:16 ` Michael Cree
2014-09-05 18:09 ` Paul E. McKenney
2014-09-05 18:09 ` Paul E. McKenney
2014-09-05 18:31 ` Paul E. McKenney
2014-09-05 19:52 ` Peter Zijlstra
2014-09-05 19:52 ` Peter Zijlstra
2014-09-05 20:01 ` Peter Hurley
2014-09-05 20:01 ` Peter Hurley
2014-09-05 20:12 ` Peter Zijlstra
2014-09-05 20:12 ` Peter Zijlstra
2014-09-05 20:15 ` H. Peter Anvin
2014-09-05 20:15 ` H. Peter Anvin
2014-09-05 20:19 ` Paul E. McKenney
2014-09-05 20:19 ` Paul E. McKenney
2014-09-05 18:50 ` Peter Hurley
2014-09-05 18:50 ` Peter Hurley
2014-09-05 19:05 ` Paul E. McKenney
2014-09-05 19:05 ` Paul E. McKenney
2014-09-05 19:24 ` Peter Hurley
2014-09-05 19:24 ` Peter Hurley
2014-09-05 20:09 ` Paul E. McKenney
2014-09-05 20:09 ` Paul E. McKenney
2014-09-05 19:38 ` Marc Gauthier
2014-09-05 19:38 ` Marc Gauthier
2014-09-05 20:14 ` Peter Hurley
2014-09-05 20:14 ` Peter Hurley
2014-09-05 20:34 ` H. Peter Anvin
2014-09-05 20:34 ` H. Peter Anvin
2014-09-05 20:42 ` Michael Cree
2014-09-05 20:42 ` Michael Cree
2014-09-05 20:43 ` Paul E. McKenney
2014-09-05 20:48 ` Thomas Gleixner
2014-09-05 20:48 ` Thomas Gleixner
2014-09-05 21:05 ` Paul E. McKenney
2014-09-05 21:05 ` Paul E. McKenney
2014-09-05 20:39 ` Michael Cree
2014-09-05 20:39 ` Michael Cree
2014-09-05 21:12 ` Peter Hurley
2014-09-05 21:27 ` Michael Cree
2014-09-05 21:27 ` Michael Cree
2014-09-05 20:42 ` Paul E. McKenney
2014-09-05 20:42 ` Paul E. McKenney
2014-09-05 2:08 ` H. Peter Anvin
2014-09-05 2:08 ` H. Peter Anvin
2014-09-05 15:31 ` Peter Hurley
2014-09-05 15:41 ` H. Peter Anvin
2014-09-05 15:41 ` H. Peter Anvin
2014-09-08 17:52 ` One Thousand Gnomes
2014-09-08 17:52 ` One Thousand Gnomes
2014-09-08 17:59 ` H. Peter Anvin
2014-09-08 17:59 ` H. Peter Anvin
2014-09-08 19:17 ` One Thousand Gnomes
2014-09-09 11:18 ` Peter Hurley
2014-09-09 11:18 ` Peter Hurley
2014-09-08 22:47 ` Peter Hurley
2014-09-08 22:47 ` Peter Hurley
2014-09-09 1:59 ` Paul E. McKenney
2014-09-09 1:59 ` Paul E. McKenney
2014-09-09 11:14 ` Peter Hurley
2014-09-11 10:04 ` One Thousand Gnomes
2014-09-11 16:16 ` Paul E. McKenney
2014-09-11 20:01 ` Peter Hurley
2014-09-11 20:01 ` Peter Hurley
2014-09-14 23:24 ` One Thousand Gnomes
2014-09-22 19:51 ` Paul E. McKenney
2014-09-22 19:51 ` Paul E. McKenney
2014-09-23 18:19 ` Peter Hurley
2014-09-23 18:39 ` One Thousand Gnomes
2014-09-23 18:39 ` One Thousand Gnomes
2014-09-08 18:13 ` James Bottomley
2014-09-08 18:13 ` James Bottomley
2014-09-10 20:18 ` H. Peter Anvin
2014-09-10 21:10 ` Rob Landley
2014-09-04 8:57 ` Mikael Pettersson
2014-09-04 8:57 ` Mikael Pettersson
2014-09-04 9:09 ` Jakub Jelinek
2014-09-04 12:24 ` Peter Hurley
2014-09-04 12:24 ` Peter Hurley
2014-09-04 12:29 ` Jakub Jelinek
2014-09-04 12:29 ` Jakub Jelinek
2014-09-04 16:50 ` One Thousand Gnomes
2014-09-04 16:50 ` One Thousand Gnomes
2014-09-04 19:42 ` Peter Hurley
2014-09-04 19:42 ` Peter Hurley
2014-09-04 22:16 ` H. Peter Anvin
2014-09-04 22:16 ` H. Peter Anvin
2014-09-05 0:17 ` Paul E. McKenney
2014-09-05 1:57 ` Peter Hurley
2014-09-05 1:57 ` Peter Hurley
2014-09-05 2:11 ` James Bottomley
2014-09-05 2:47 ` Peter Hurley
2014-09-05 2:47 ` Peter Hurley
2014-09-05 4:06 ` Paul E. McKenney
2014-09-05 8:30 ` David Laight
2014-09-05 8:30 ` David Laight
2014-09-05 12:31 ` Peter Hurley
2014-09-05 12:31 ` Peter Hurley
2014-09-05 12:37 ` David Laight
2014-09-05 12:37 ` David Laight
2014-09-05 16:17 ` Peter Hurley
2014-09-05 16:17 ` Peter Hurley
2014-09-25 16:12 ` Pavel Machek
2014-09-07 5:07 ` James Bottomley
2014-09-07 5:07 ` James Bottomley
2014-09-07 16:21 ` Paul E. McKenney
2014-09-07 16:21 ` Paul E. McKenney
2014-09-07 19:04 ` James Bottomley
2014-09-07 19:04 ` James Bottomley
2014-09-07 20:41 ` Peter Hurley
2014-09-08 5:50 ` James Bottomley
2014-09-08 5:50 ` James Bottomley
2014-09-08 20:45 ` Chris Metcalf
2014-09-08 20:45 ` Chris Metcalf
2014-09-08 22:43 ` James Bottomley
2014-09-08 22:43 ` James Bottomley
2014-09-09 2:27 ` H. Peter Anvin
2014-09-09 2:27 ` H. Peter Anvin
2014-09-09 8:11 ` Arnd Bergmann
2014-09-08 23:30 ` Peter Hurley
2014-09-08 23:30 ` Peter Hurley
2014-09-09 2:56 ` James Bottomley
2014-09-09 3:20 ` H. Peter Anvin
2014-09-09 3:20 ` H. Peter Anvin
2014-09-09 4:30 ` H. Peter Anvin
2014-09-09 4:30 ` H. Peter Anvin
2014-09-09 10:40 ` Peter Hurley
2014-09-09 10:40 ` Peter Hurley
2014-09-10 21:48 ` James Bottomley
2014-09-10 23:50 ` Peter Hurley
2014-09-10 23:50 ` Peter Hurley
2014-09-11 10:23 ` Will Deacon
2014-09-11 10:23 ` Will Deacon
2014-09-07 23:00 ` Paul E. McKenney
2014-09-07 23:00 ` Paul E. McKenney
2014-09-07 23:17 ` H. Peter Anvin
2014-09-07 23:17 ` H. Peter Anvin
2014-09-07 23:36 ` Paul E. McKenney
2014-09-07 23:36 ` Paul E. McKenney
2014-09-07 23:39 ` H. Peter Anvin
2014-09-07 23:39 ` H. Peter Anvin
2014-09-08 5:56 ` James Bottomley
2014-09-08 18:12 ` H. Peter Anvin
2014-09-08 19:09 ` James Bottomley
2014-09-08 19:12 ` H. Peter Anvin [this message]
2014-09-08 19:12 ` H. Peter Anvin
2014-09-08 22:39 ` James Bottomley
2014-09-08 22:39 ` James Bottomley
2014-09-09 2:30 ` H. Peter Anvin
2014-09-09 2:30 ` H. Peter Anvin
2014-09-08 19:12 ` H. Peter Anvin
2014-09-08 19:12 ` H. Peter Anvin
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