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From: Oleg Nesterov <oleg@tv-sign.ru>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Jens Axboe <jens.axboe@oracle.com>,
	Alan Stern <stern@rowland.harvard.edu>,
	Linus Torvalds <torvalds@osdl.org>,
	Thomas Gleixner <tglx@timesys.com>, Ingo Molnar <mingo@elte.hu>,
	LKML <linux-kernel@vger.kernel.org>,
	john stultz <johnstul@us.ibm.com>,
	David Miller <davem@davemloft.net>,
	Arjan van de Ven <arjan@infradead.org>,
	Andrew Morton <akpm@osdl.org>, Andi Kleen <ak@suse.de>,
	manfred@colorfullife.com
Subject: Re: [patch] cpufreq: mark cpufreq_tsc() as core_initcall_sync
Date: Sat, 18 Nov 2006 21:46:24 +0300	[thread overview]
Message-ID: <20061118184624.GA163@oleg> (raw)
In-Reply-To: <20061118002845.GF2632@us.ibm.com>

On 11/17, Paul E. McKenney wrote:
>
> Oleg, any thoughts about Jens's optimization?  He would code something
> like:
> 
> 	if (srcu_readers_active(&my_srcu))
> 		synchronize_srcu();
> 	else
> 		smp_mb();

Well, this is clearly racy, no? I am not sure, but may be we can do

	smp_mb();
	if (srcu_readers_active(&my_srcu))
		synchronize_srcu();

in this case we also need to add 'smp_mb()' into srcu_read_lock() after
'atomic_inc(&sp->hardluckref)'.

> However, he is doing ordered I/O requests rather than protecting data
> structures.

Probably this makes a difference, but I don't understand this.

Oleg.


  parent reply	other threads:[~2006-11-18 18:47 UTC|newest]

Thread overview: 108+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-11-16 20:00 BUG: cpufreq notification broken Thomas Gleixner
2006-11-16 20:15 ` [patch] cpufreq: mark cpufreq_tsc() as core_initcall_sync Ingo Molnar
2006-11-16 20:45   ` Thomas Gleixner
2006-11-16 21:47     ` Linus Torvalds
2006-11-16 22:03       ` Alan Stern
2006-11-16 22:21         ` Linus Torvalds
2006-11-17  3:06           ` Alan Stern
2006-11-17  6:51             ` Paul E. McKenney
2006-11-17  9:29               ` Jens Axboe
2006-11-17 18:39                 ` Oleg Nesterov
2006-11-18  0:28                   ` Paul E. McKenney
2006-11-18 16:15                     ` Alan Stern
2006-11-18 17:14                       ` Paul E. McKenney
2006-11-18 19:34                         ` Oleg Nesterov
2006-11-19 21:26                           ` Paul E. McKenney
2006-11-18 21:00                         ` Alan Stern
2006-11-18 21:25                           ` Oleg Nesterov
2006-11-18 22:13                             ` Alan Stern
2006-11-18 22:46                               ` Oleg Nesterov
2006-11-19 20:12                                 ` Alan Stern
2006-11-19 21:43                           ` Paul E. McKenney
2006-11-20 17:19                             ` Alan Stern
2006-11-20 17:58                               ` Jens Axboe
2006-11-20 19:39                                 ` Alan Stern
2006-11-20 20:13                                   ` Jens Axboe
2006-11-20 21:39                                     ` Alan Stern
2006-11-21  7:39                                       ` Jens Axboe
2006-11-20 18:57                               ` Oleg Nesterov
2006-11-20 20:01                                 ` Alan Stern
2006-11-20 20:51                                   ` Paul E. McKenney
2006-11-21 20:04                                   ` Oleg Nesterov
2006-11-21 20:54                                     ` Alan Stern
2006-11-21 22:07                                     ` Paul E. McKenney
2006-11-20 20:38                                 ` Paul E. McKenney
2006-11-21 16:44                                   ` Oleg Nesterov
2006-11-21 19:56                                     ` Paul E. McKenney
2006-11-21 20:26                                       ` Alan Stern
2006-11-21 23:03                                         ` Paul E. McKenney
2006-11-22  2:17                                           ` Alan Stern
2006-11-22 17:01                                             ` Paul E. McKenney
2006-11-26 22:25                                 ` Oleg Nesterov
2006-11-27 21:10                                   ` Alan Stern
2006-11-28  1:47                                     ` Paul E. McKenney
2006-11-20 19:17                               ` Paul E. McKenney
2006-11-20 20:22                                 ` Alan Stern
2006-11-21 17:55                                   ` Paul E. McKenney
2006-11-21 17:56                             ` Alan Stern
2006-11-21 19:13                               ` Paul E. McKenney
2006-11-21 20:40                                 ` Alan Stern
2006-11-22 18:08                                   ` Paul E. McKenney
2006-11-21 21:01                                 ` Oleg Nesterov
2006-11-22  0:51                                   ` Paul E. McKenney
2006-11-18 18:46                     ` Oleg Nesterov [this message]
2006-11-19 21:07                       ` Paul E. McKenney
2006-11-20  7:15                         ` Jens Axboe
2006-11-20 16:59                           ` Paul E. McKenney
2006-11-20 17:55                             ` Jens Axboe
2006-11-20 20:09                               ` Paul E. McKenney
2006-11-20 20:21                                 ` Jens Axboe
2006-11-18 19:02                     ` Oleg Nesterov
2006-11-19 21:23                       ` Paul E. McKenney
2006-11-17 19:15                 ` Paul E. McKenney
2006-11-17 19:27                   ` Alan Stern
2006-11-18  0:38                     ` Paul E. McKenney
2006-11-18  4:33                       ` Alan Stern
2006-11-18  4:51                         ` Andrew Morton
2006-11-18  5:57                           ` Paul E. McKenney
2006-11-19 19:00                 ` Oleg Nesterov
2006-11-19 20:21                   ` Alan Stern
2006-11-19 20:55                     ` Oleg Nesterov
2006-11-19 21:09                       ` Alan Stern
2006-11-19 21:17                         ` Oleg Nesterov
2006-11-19 21:54                           ` Paul E. McKenney
2006-11-19 22:28                             ` Oleg Nesterov
2006-11-20  5:47                               ` Paul E. McKenney
2006-11-19 21:20                       ` Paul E. McKenney
2006-11-19 21:50                         ` Oleg Nesterov
2006-11-19 22:04                           ` Paul E. McKenney
2006-11-23 14:59                   ` Oleg Nesterov
2006-11-23 20:40                     ` Paul E. McKenney
2006-11-23 21:34                       ` Oleg Nesterov
2006-11-23 21:49                       ` Oleg Nesterov
2006-11-27  4:33                         ` Paul E. McKenney
2006-11-24 18:21                     ` Oleg Nesterov
2006-11-24 20:04                       ` Jens Axboe
2006-11-24 20:47                       ` Alan Stern
2006-11-24 21:13                         ` Oleg Nesterov
2006-11-25  3:24                           ` Alan Stern
2006-11-25 17:14                             ` Oleg Nesterov
2006-11-25 22:06                               ` Alan Stern
2006-11-26 21:34                                 ` Oleg Nesterov
2006-11-27  5:02                       ` Paul E. McKenney
2006-11-27 16:11                         ` Oleg Nesterov
2006-11-27 16:56                           ` Oleg Nesterov
2006-11-29 19:29                           ` Paul E. McKenney
2006-11-29 20:16                             ` Oleg Nesterov
2006-11-29 23:08                               ` Paul E. McKenney
2006-11-30  0:01                                 ` Oleg Nesterov
2006-11-17  2:33       ` Paul E. McKenney
2006-11-16 20:52   ` Peter Zijlstra
2006-11-16 21:20   ` Andrew Morton
2006-11-16 21:27     ` Thomas Gleixner
2006-11-20 19:57   ` Linus Torvalds
2006-11-16 20:27 ` BUG: cpufreq notification broken Alan Stern
2006-11-16 21:09   ` Thomas Gleixner
2006-11-16 21:26     ` Alan Stern
2006-11-16 21:36       ` Thomas Gleixner
2006-11-16 21:56         ` Alan Stern

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