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From: Byungchul Park <byungchul.park@lge.com>
To: Petr Mladek <pmladek@suse.com>
Cc: Steven Rostedt <rostedt@goodmis.org>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	akpm@linux-foundation.org, linux-mm@kvack.org,
	Cong Wang <xiyou.wangcong@gmail.com>,
	Dave Hansen <dave.hansen@intel.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Mel Gorman <mgorman@suse.de>, Michal Hocko <mhocko@kernel.org>,
	Vlastimil Babka <vbabka@suse.cz>,
	Peter Zijlstra <peterz@infradead.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Jan Kara <jack@suse.cz>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
	rostedt@home.goodmis.org,
	Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
	Tejun Heo <tj@kernel.org>, Pavel Machek <pavel@ucw.cz>,
	linux-kernel@vger.kernel.org, kernel-team@lge.com
Subject: Re: [PATCH v5 1/2] printk: Add console owner and waiter logic to load balance console writes
Date: Thu, 18 Jan 2018 10:57:13 +0900	[thread overview]
Message-ID: <7a107b1e-f99f-186b-f5db-504b7691993d@lge.com> (raw)
In-Reply-To: <4a24ce1d-a606-3add-ec30-91ce9a1a1281@lge.com>

On 1/18/2018 10:53 AM, Byungchul Park wrote:
> Hello,
> 
> This is a thing simulating a wait for an event e.g.
> wait_for_completion() doing spinning instead of sleep, rather
> than a spinlock. I mean:
> 
>  A A  This context
>  A A  ------------
>  A A  while (READ_ONCE(console_waiter)) /* Wait for the event */
>  A A A A A  cpu_relax();
> 
>  A A  Another context
>  A A  ---------------
>  A A  WRITE_ONCE(console_waiter, false); /* Event */
> 
> That's why I said this's the exact case of cross-release. Anyway
> without cross-release, we usually use typical acquire/release
> pairs to cover a wait for an event in the following way:
> 
>  A A  A context
>  A A  ---------
>  A A  lock_map_acquire(wait); /* Or lock_map_acquire_read(wait) */
>  A A A A A A A A A A A A A A A A A A A A A A A A A A  /* Read one is better though..A A A  */
> 
>  A A  /* A section, we suspect, a wait for an event might happen. */
>  A A  ...
>  A A  lock_map_release(wait);
> 
> 
>  A A  The place actually doing the wait
>  A A  ---------------------------------
>  A A  lock_map_acquire(wait);
>  A A  lock_map_acquire(wait);
       ^
       lock_map_release(wait);

-- 
Thanks,
Byungchul

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  reply	other threads:[~2018-01-18  1:57 UTC|newest]

Thread overview: 140+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-10 13:24 [PATCH v5 0/2] printk: Console owner and waiter logic cleanup Petr Mladek
2018-01-10 13:24 ` [PATCH v5 1/2] printk: Add console owner and waiter logic to load balance console writes Petr Mladek
2018-01-10 16:50   ` Steven Rostedt
2018-01-12 16:54   ` Steven Rostedt
2018-01-12 17:11     ` Steven Rostedt
2018-01-17 19:13       ` Rasmus Villemoes
2018-01-17 19:33         ` Steven Rostedt
2018-01-19  9:51         ` Sergey Senozhatsky
2018-01-18 22:03     ` Pavel Machek
2018-01-19  0:20       ` Steven Rostedt
2018-01-17  2:19   ` Byungchul Park
2018-01-17  4:54     ` Byungchul Park
2018-01-17  7:34     ` Byungchul Park
2018-01-17 12:04     ` Petr Mladek
2018-01-18  1:53       ` Byungchul Park
2018-01-18  1:57         ` Byungchul Park [this message]
2018-01-18  2:19         ` Steven Rostedt
2018-01-18  4:01           ` Byungchul Park
2018-01-18 15:21             ` Steven Rostedt
2018-01-19  2:37               ` Byungchul Park
2018-01-19  3:27                 ` Steven Rostedt
2018-01-22  2:31                   ` Byungchul Park
2018-01-10 13:24 ` [PATCH v5 2/2] printk: Hide console waiter logic into helpers Petr Mladek
2018-01-10 17:52   ` Steven Rostedt
2018-01-11 12:03     ` Petr Mladek
2018-01-12 15:37       ` Steven Rostedt
2018-01-12 16:08         ` Petr Mladek
2018-01-12 16:36           ` Steven Rostedt
2018-01-15 16:08             ` Petr Mladek
2018-01-16  5:05               ` Sergey Senozhatsky
2018-01-10 14:05 ` [PATCH v5 0/2] printk: Console owner and waiter logic cleanup Tejun Heo
2018-01-10 16:29   ` Petr Mladek
2018-01-10 17:02     ` Tejun Heo
2018-01-10 18:21       ` Peter Zijlstra
2018-01-10 18:30         ` Tejun Heo
2018-01-10 18:41           ` Peter Zijlstra
2018-01-10 19:05             ` Tejun Heo
2018-01-11  5:15         ` Sergey Senozhatsky
2018-01-10 18:22       ` Steven Rostedt
2018-01-10 18:36         ` Tejun Heo
2018-01-10 18:40       ` Mathieu Desnoyers
2018-01-11  7:36         ` Sergey Senozhatsky
2018-01-11 11:24           ` Petr Mladek
2018-01-11 13:19             ` Sergey Senozhatsky
2018-01-24  9:36       ` Peter Zijlstra
2018-01-24 18:46         ` Tejun Heo
2018-05-09  8:58       ` Sergey Senozhatsky
2018-01-10 18:54     ` Steven Rostedt
2018-01-11  5:10     ` Sergey Senozhatsky
2018-01-10 18:05   ` Steven Rostedt
2018-01-10 18:12     ` Tejun Heo
2018-01-10 18:14       ` Tejun Heo
2018-01-10 18:45         ` Steven Rostedt
2018-01-10 18:41       ` Steven Rostedt
2018-01-10 18:57         ` Tejun Heo
2018-01-10 19:17           ` Steven Rostedt
2018-01-10 19:34             ` Tejun Heo
2018-01-10 19:44               ` Steven Rostedt
2018-01-10 22:44                 ` Tejun Heo
2018-01-11  5:35             ` Sergey Senozhatsky
2018-01-11  4:58     ` Sergey Senozhatsky
2018-01-11  9:34       ` Petr Mladek
2018-01-11 10:38         ` Sergey Senozhatsky
2018-01-11 11:50           ` Petr Mladek
2018-01-11 16:29           ` Steven Rostedt
2018-01-12  1:30             ` Steven Rostedt
2018-01-12  2:55               ` Steven Rostedt
2018-01-12  4:20                 ` Steven Rostedt
2018-01-16 19:44                 ` Tejun Heo
2018-01-17  9:12                   ` Petr Mladek
2018-01-17 15:15                     ` Tejun Heo
2018-01-17 17:12                       ` Steven Rostedt
2018-01-17 18:42                         ` Steven Rostedt
2018-01-19 18:20                           ` Steven Rostedt
2018-01-20  7:14                             ` Sergey Senozhatsky
2018-01-20 15:49                               ` Steven Rostedt
2018-01-21 14:15                                 ` Sergey Senozhatsky
2018-01-21 21:04                                   ` Steven Rostedt
2018-01-22  8:56                                     ` Sergey Senozhatsky
2018-01-22 10:28                                       ` Sergey Senozhatsky
2018-01-22 10:36                                         ` Sergey Senozhatsky
2018-01-23  6:40                                   ` Sergey Senozhatsky
2018-01-23  7:05                                     ` Sergey Senozhatsky
2018-01-23  7:31                                     ` Sergey Senozhatsky
2018-01-23 14:56                                     ` Steven Rostedt
2018-01-23 15:21                                       ` Sergey Senozhatsky
2018-01-23 15:41                                         ` Steven Rostedt
2018-01-23 15:43                                           ` Tejun Heo
2018-01-23 16:12                                             ` Sergey Senozhatsky
2018-01-23 16:13                                             ` Steven Rostedt
2018-01-23 17:21                                               ` Tejun Heo
2018-04-23  5:35                                             ` Sergey Senozhatsky
2018-01-23 16:01                                           ` Sergey Senozhatsky
2018-01-23 16:24                                             ` Steven Rostedt
2018-01-24  2:11                                               ` Sergey Senozhatsky
2018-01-24  2:52                                                 ` Steven Rostedt
2018-01-24  4:44                                                   ` Sergey Senozhatsky
2018-01-23 17:22                                             ` Tejun Heo
2018-01-20 12:19                             ` Tejun Heo
2018-01-20 14:51                               ` Steven Rostedt
2018-01-17 20:05                         ` Tejun Heo
2018-01-18  5:43                           ` Sergey Senozhatsky
2018-01-18 11:51                           ` Petr Mladek
2018-01-18  5:42                         ` Sergey Senozhatsky
2018-01-12  3:12               ` Sergey Senozhatsky
2018-01-12  2:56             ` Sergey Senozhatsky
2018-01-12  3:21               ` Steven Rostedt
2018-01-12 10:05                 ` Sergey Senozhatsky
2018-01-12 12:21                   ` Steven Rostedt
2018-01-12 12:55                     ` Petr Mladek
2018-01-13  7:31                       ` Sergey Senozhatsky
2018-01-15  8:51                         ` Petr Mladek
2018-01-15  9:48                           ` Sergey Senozhatsky
2018-01-16  5:16                           ` Sergey Senozhatsky
2018-01-16  9:08                             ` Petr Mladek
2018-01-15 12:08                       ` Steven Rostedt
2018-01-16  4:51                         ` Sergey Senozhatsky
2018-01-13  7:28                     ` Sergey Senozhatsky
2018-01-15 10:17                       ` Petr Mladek
2018-01-15 11:50                         ` Petr Mladek
2018-01-16  6:10                           ` Sergey Senozhatsky
2018-01-16  9:36                             ` Petr Mladek
2018-01-16 10:10                               ` Sergey Senozhatsky
2018-01-16 16:06                             ` Steven Rostedt
2018-01-16  5:23                         ` Sergey Senozhatsky
2018-01-15 12:06                       ` Steven Rostedt
2018-01-15 14:45                         ` Petr Mladek
2018-01-16  2:23                           ` Sergey Senozhatsky
2018-01-16  4:47                             ` Sergey Senozhatsky
2018-01-16 10:19                               ` Petr Mladek
2018-01-17  2:24                                 ` Sergey Senozhatsky
2018-01-16 15:45                               ` Steven Rostedt
2018-01-17  2:18                                 ` Sergey Senozhatsky
2018-01-17 13:04                                   ` Petr Mladek
2018-01-17 15:24                                     ` Steven Rostedt
2018-01-18  4:31                                     ` Sergey Senozhatsky
2018-01-18 15:22                                       ` Steven Rostedt
2018-01-16 10:13                             ` Petr Mladek
2018-01-17  6:29                               ` Sergey Senozhatsky
2018-01-16  1:46                         ` Sergey Senozhatsky

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