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From: Victor Kaplansky <VICTORK@il.ibm.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Anton Blanchard <anton@samba.org>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Linux PPC dev <linuxppc-dev@ozlabs.org>,
	Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>,
	Michael Ellerman <michael@ellerman.id.au>,
	Michael Neuling <mikey@neuling.org>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Peter Zijlstra <peterz@infradead.org>
Subject: Re: perf events ring buffer memory barrier on powerpc
Date: Mon, 28 Oct 2013 22:58:58 +0200	[thread overview]
Message-ID: <OF58D85F5A.03E37A80-ON42257C12.0070E552-42257C12.00734308@il.ibm.com> (raw)
In-Reply-To: <20131028201735.GA15629@redhat.com>

Oleg Nesterov <oleg@redhat.com> wrote on 10/28/2013 10:17:35 PM:

>       mb();   // XXXXXXXX: do we really need it? I think yes.

Oh, it is hard to argue with feelings. Also, it is easy to be on
conservative side and put the barrier here just in case.
But I still insist that the barrier is redundant in your example.

-- Victor


WARNING: multiple messages have this Message-ID (diff)
From: Victor Kaplansky <VICTORK@il.ibm.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Michael Neuling <mikey@neuling.org>,
	Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>,
	Peter Zijlstra <peterz@infradead.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Linux PPC dev <linuxppc-dev@ozlabs.org>,
	Anton Blanchard <anton@samba.org>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: Re: perf events ring buffer memory barrier on powerpc
Date: Mon, 28 Oct 2013 22:58:58 +0200	[thread overview]
Message-ID: <OF58D85F5A.03E37A80-ON42257C12.0070E552-42257C12.00734308@il.ibm.com> (raw)
In-Reply-To: <20131028201735.GA15629@redhat.com>

Oleg Nesterov <oleg@redhat.com> wrote on 10/28/2013 10:17:35 PM:

>       mb();   // XXXXXXXX: do we really need it? I think yes.

Oh, it is hard to argue with feelings. Also, it is easy to be on
conservative side and put the barrier here just in case.
But I still insist that the barrier is redundant in your example.

-- Victor

  reply	other threads:[~2013-10-28 20:59 UTC|newest]

Thread overview: 215+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-10-22 23:54 perf events ring buffer memory barrier on powerpc Michael Neuling
2013-10-23  7:39 ` Victor Kaplansky
2013-10-23  7:39   ` Victor Kaplansky
2013-10-23 14:19 ` Frederic Weisbecker
2013-10-23 14:19   ` Frederic Weisbecker
2013-10-23 14:25   ` Frederic Weisbecker
2013-10-23 14:25     ` Frederic Weisbecker
2013-10-25 17:37   ` Peter Zijlstra
2013-10-25 17:37     ` Peter Zijlstra
2013-10-25 20:31     ` Michael Neuling
2013-10-25 20:31       ` Michael Neuling
2013-10-27  9:00     ` Victor Kaplansky
2013-10-27  9:00       ` Victor Kaplansky
2013-10-28  9:22       ` Peter Zijlstra
2013-10-28  9:22         ` Peter Zijlstra
2013-10-28 10:02     ` Frederic Weisbecker
2013-10-28 10:02       ` Frederic Weisbecker
2013-10-28 12:38       ` Victor Kaplansky
2013-10-28 12:38         ` Victor Kaplansky
2013-10-28 13:26         ` Peter Zijlstra
2013-10-28 13:26           ` Peter Zijlstra
2013-10-28 16:34           ` Paul E. McKenney
2013-10-28 16:34             ` Paul E. McKenney
2013-10-28 20:17             ` Oleg Nesterov
2013-10-28 20:17               ` Oleg Nesterov
2013-10-28 20:58               ` Victor Kaplansky [this message]
2013-10-28 20:58                 ` Victor Kaplansky
2013-10-29 10:21                 ` Peter Zijlstra
2013-10-29 10:21                   ` Peter Zijlstra
2013-10-29 10:30                   ` Peter Zijlstra
2013-10-29 10:30                     ` Peter Zijlstra
2013-10-29 10:35                     ` Peter Zijlstra
2013-10-29 10:35                       ` Peter Zijlstra
2013-10-29 20:15                       ` Oleg Nesterov
2013-10-29 20:15                         ` Oleg Nesterov
2013-10-29 19:27                     ` Vince Weaver
2013-10-29 19:27                       ` Vince Weaver
2013-10-30 10:42                       ` Peter Zijlstra
2013-10-30 10:42                         ` Peter Zijlstra
2013-10-30 11:48                         ` James Hogan
2013-10-30 11:48                           ` James Hogan
2013-10-30 12:48                           ` Peter Zijlstra
2013-10-30 12:48                             ` Peter Zijlstra
2013-11-06 13:19                         ` [tip:perf/core] tools/perf: Add required memory barriers tip-bot for Peter Zijlstra
2013-11-06 13:50                           ` Vince Weaver
2013-11-06 14:00                             ` Peter Zijlstra
2013-11-06 14:28                               ` Peter Zijlstra
2013-11-06 14:55                                 ` Vince Weaver
2013-11-06 15:10                                   ` Peter Zijlstra
2013-11-06 15:23                                     ` Peter Zijlstra
2013-11-06 14:44                               ` Peter Zijlstra
2013-11-06 16:07                                 ` Peter Zijlstra
2013-11-06 17:31                                   ` Vince Weaver
2013-11-06 18:24                                     ` Peter Zijlstra
2013-11-07  8:21                                       ` Ingo Molnar
2013-11-07 14:27                                         ` Vince Weaver
2013-11-07 15:55                                           ` Ingo Molnar
2013-11-11 16:24                                         ` Peter Zijlstra
2013-11-11 21:10                                           ` Ingo Molnar
2013-10-29 21:23                     ` perf events ring buffer memory barrier on powerpc Michael Neuling
2013-10-29 21:23                       ` Michael Neuling
2013-10-30  9:27                 ` Paul E. McKenney
2013-10-30  9:27                   ` Paul E. McKenney
2013-10-30 11:25                   ` Peter Zijlstra
2013-10-30 11:25                     ` Peter Zijlstra
2013-10-30 14:52                     ` Victor Kaplansky
2013-10-30 14:52                       ` Victor Kaplansky
2013-10-30 15:39                       ` Peter Zijlstra
2013-10-30 15:39                         ` Peter Zijlstra
2013-10-30 17:14                         ` Victor Kaplansky
2013-10-30 17:14                           ` Victor Kaplansky
2013-10-30 17:44                           ` Peter Zijlstra
2013-10-30 17:44                             ` Peter Zijlstra
2013-10-31  6:16                       ` Paul E. McKenney
2013-10-31  6:16                         ` Paul E. McKenney
2013-11-01 13:12                         ` Victor Kaplansky
2013-11-01 13:12                           ` Victor Kaplansky
2013-11-02 16:36                           ` Paul E. McKenney
2013-11-02 16:36                             ` Paul E. McKenney
2013-11-02 17:26                             ` Paul E. McKenney
2013-11-02 17:26                               ` Paul E. McKenney
2013-10-31  6:40                     ` Paul E. McKenney
2013-10-31  6:40                       ` Paul E. McKenney
2013-11-01 14:25                       ` Victor Kaplansky
2013-11-01 14:25                         ` Victor Kaplansky
2013-11-02 17:28                         ` Paul E. McKenney
2013-11-02 17:28                           ` Paul E. McKenney
2013-11-01 14:56                       ` Peter Zijlstra
2013-11-01 14:56                         ` Peter Zijlstra
2013-11-02 17:32                         ` Paul E. McKenney
2013-11-02 17:32                           ` Paul E. McKenney
2013-11-03 14:40                           ` Paul E. McKenney
2013-11-03 14:40                             ` Paul E. McKenney
2013-11-03 15:17                             ` [RFC] arch: Introduce new TSO memory barrier smp_tmb() Peter Zijlstra
2013-11-03 15:17                               ` Peter Zijlstra
2013-11-03 18:08                               ` Linus Torvalds
2013-11-03 18:08                                 ` Linus Torvalds
2013-11-03 20:01                                 ` Peter Zijlstra
2013-11-03 20:01                                   ` Peter Zijlstra
2013-11-03 22:42                                   ` Paul E. McKenney
2013-11-03 22:42                                     ` Paul E. McKenney
2013-11-03 23:34                                     ` Linus Torvalds
2013-11-03 23:34                                       ` Linus Torvalds
2013-11-04 10:51                                       ` Paul E. McKenney
2013-11-04 10:51                                         ` Paul E. McKenney
2013-11-04 11:22                                         ` Peter Zijlstra
2013-11-04 11:22                                           ` Peter Zijlstra
2013-11-04 16:27                                           ` Paul E. McKenney
2013-11-04 16:27                                             ` Paul E. McKenney
2013-11-04 16:48                                             ` Peter Zijlstra
2013-11-04 16:48                                               ` Peter Zijlstra
2013-11-04 19:11                                             ` Peter Zijlstra
2013-11-04 19:11                                               ` Peter Zijlstra
2013-11-04 19:18                                               ` Peter Zijlstra
2013-11-04 19:18                                                 ` Peter Zijlstra
2013-11-04 20:54                                                 ` Paul E. McKenney
2013-11-04 20:54                                                   ` Paul E. McKenney
2013-11-04 20:53                                               ` Paul E. McKenney
2013-11-04 20:53                                                 ` Paul E. McKenney
2013-11-05 14:05                                                 ` Will Deacon
2013-11-05 14:05                                                   ` Will Deacon
2013-11-05 14:49                                                   ` Paul E. McKenney
2013-11-05 14:49                                                     ` Paul E. McKenney
2013-11-05 18:49                                                   ` Peter Zijlstra
2013-11-05 18:49                                                     ` Peter Zijlstra
2013-11-06 11:00                                                     ` Will Deacon
2013-11-06 11:00                                                       ` Will Deacon
2013-11-06 12:39                                                 ` Peter Zijlstra
2013-11-06 12:39                                                   ` Peter Zijlstra
2013-11-06 12:51                                                   ` Geert Uytterhoeven
2013-11-06 12:51                                                     ` Geert Uytterhoeven
2013-11-06 13:57                                                     ` Peter Zijlstra
2013-11-06 13:57                                                       ` Peter Zijlstra
2013-11-06 18:48                                                       ` Paul E. McKenney
2013-11-06 18:48                                                         ` Paul E. McKenney
2013-11-06 19:42                                                         ` Peter Zijlstra
2013-11-06 19:42                                                           ` Peter Zijlstra
2013-11-07 11:17                                                       ` Will Deacon
2013-11-07 11:17                                                         ` Will Deacon
2013-11-07 13:36                                                         ` Peter Zijlstra
2013-11-07 13:36                                                           ` Peter Zijlstra
2013-11-07 23:50                                           ` Mathieu Desnoyers
2013-11-07 23:50                                             ` Mathieu Desnoyers
2013-11-04 11:05                                       ` Will Deacon
2013-11-04 11:05                                         ` Will Deacon
2013-11-04 16:34                                         ` Paul E. McKenney
2013-11-04 16:34                                           ` Paul E. McKenney
2013-11-03 20:59                               ` Benjamin Herrenschmidt
2013-11-03 20:59                                 ` Benjamin Herrenschmidt
2013-11-03 22:43                                 ` Paul E. McKenney
2013-11-03 22:43                                   ` Paul E. McKenney
2013-11-03 17:07                             ` perf events ring buffer memory barrier on powerpc Will Deacon
2013-11-03 22:47                               ` Paul E. McKenney
2013-11-04  9:57                                 ` Will Deacon
2013-11-04 10:52                                   ` Paul E. McKenney
2013-11-01 16:11                       ` Peter Zijlstra
2013-11-01 16:11                         ` Peter Zijlstra
2013-11-02 17:46                         ` Paul E. McKenney
2013-11-02 17:46                           ` Paul E. McKenney
2013-11-01 16:18                       ` Peter Zijlstra
2013-11-01 16:18                         ` Peter Zijlstra
2013-11-02 17:49                         ` Paul E. McKenney
2013-11-02 17:49                           ` Paul E. McKenney
2013-10-30 13:28                   ` Victor Kaplansky
2013-10-30 13:28                     ` Victor Kaplansky
2013-10-30 15:51                     ` Peter Zijlstra
2013-10-30 15:51                       ` Peter Zijlstra
2013-10-30 18:29                       ` Peter Zijlstra
2013-10-30 18:29                         ` Peter Zijlstra
2013-10-30 19:11                         ` Peter Zijlstra
2013-10-30 19:11                           ` Peter Zijlstra
2013-10-31  4:33                       ` Paul E. McKenney
2013-10-31  4:33                         ` Paul E. McKenney
2013-10-31  4:32                     ` Paul E. McKenney
2013-10-31  4:32                       ` Paul E. McKenney
2013-10-31  9:04                       ` Peter Zijlstra
2013-10-31  9:04                         ` Peter Zijlstra
2013-10-31 15:07                         ` Paul E. McKenney
2013-10-31 15:07                           ` Paul E. McKenney
2013-10-31 15:19                           ` Peter Zijlstra
2013-10-31 15:19                             ` Peter Zijlstra
2013-11-01  9:28                             ` Paul E. McKenney
2013-11-01  9:28                               ` Paul E. McKenney
2013-11-01 10:30                               ` Peter Zijlstra
2013-11-01 10:30                                 ` Peter Zijlstra
2013-11-02 15:20                                 ` Paul E. McKenney
2013-11-02 15:20                                   ` Paul E. McKenney
2013-11-04  9:07                                   ` Peter Zijlstra
2013-11-04  9:07                                     ` Peter Zijlstra
2013-11-04 10:00                                     ` Paul E. McKenney
2013-11-04 10:00                                       ` Paul E. McKenney
2013-10-31  9:59                       ` Victor Kaplansky
2013-10-31  9:59                         ` Victor Kaplansky
2013-10-31 12:28                         ` David Laight
2013-10-31 12:28                           ` David Laight
2013-10-31 12:55                           ` Victor Kaplansky
2013-10-31 12:55                             ` Victor Kaplansky
2013-10-31 15:25                         ` Paul E. McKenney
2013-10-31 15:25                           ` Paul E. McKenney
2013-11-01 16:06                           ` Victor Kaplansky
2013-11-01 16:06                             ` Victor Kaplansky
2013-11-01 16:25                             ` David Laight
2013-11-01 16:25                               ` David Laight
2013-11-01 16:30                               ` Victor Kaplansky
2013-11-01 16:30                                 ` Victor Kaplansky
2013-11-03 20:57                                 ` Benjamin Herrenschmidt
2013-11-03 20:57                                   ` Benjamin Herrenschmidt
2013-11-02 15:46                             ` Paul E. McKenney
2013-11-02 15:46                               ` Paul E. McKenney
2013-10-28 19:09           ` Oleg Nesterov
2013-10-28 19:09             ` Oleg Nesterov
2013-10-29 14:06     ` [tip:perf/urgent] perf: Fix perf ring buffer memory ordering tip-bot for Peter Zijlstra
2014-05-08 20:46 perf events ring buffer memory barrier on powerpc Mikulas Patocka
     [not found] ` <OF667059AA.7F151BCC-ONC2257CD3.0036CFEB-C2257CD3.003BBF01@il.ibm.com>
2014-05-09 12:20   ` Mikulas Patocka
2014-05-09 13:47     ` Paul E. McKenney

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