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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Christoph Lameter <cl@linux-foundation.org>
Cc: Arjan van de Ven <arjan@infradead.org>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Peter Zijlstra <peterz@infradead.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"minchan.kim@gmail.com" <minchan.kim@gmail.com>,
	"hugh.dickins" <hugh.dickins@tiscali.co.uk>,
	Nick Piggin <nickpiggin@yahoo.com.au>,
	Ingo Molnar <mingo@elte.hu>
Subject: Re: [RFC][PATCH 6/8] mm: handle_speculative_fault()
Date: Thu, 7 Jan 2010 08:31:55 -0800 (PST)	[thread overview]
Message-ID: <alpine.LFD.2.00.1001070826410.7821@localhost.localdomain> (raw)
In-Reply-To: <alpine.LFD.2.00.1001070814080.7821@localhost.localdomain>



On Thu, 7 Jan 2010, Linus Torvalds wrote:
> 
> (Side note: I wonder if we should wake up _all_ readers when we wake up 
> any. Right now, we wake up all readers - but only until we hit a writer. 
> Which is the _fair_ thing to do, but it does mean that we can end up in 
> horrible patterns of alternating readers/writers, when it could be much 
> better to just say "release the hounds" and let all pending readers go 
> after a writer has had its turn).

Btw, this would still be "mostly fair" in the sense that you couldn't 
starve writers. Any writer on the list is still guaranteed to be woken up 
next, because now it will be at the front of the queue.

So it would be starvation-proof - new readers that come in _after_ we've 
woken up all the old ones would not get to pass the writers. It might be 
interesting to test, if somebody has a problematic threaded workload with 
lots of page faults and allocations mixxed.

			Linus

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  reply	other threads:[~2010-01-07 16:32 UTC|newest]

Thread overview: 121+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-01-04 18:24 [RFC][PATCH 0/8] Speculative pagefault -v3 Peter Zijlstra
2010-01-04 18:24 ` [RFC][PATCH 1/8] mm: Remove pte reference from fault path Peter Zijlstra
2010-01-04 18:24 ` [RFC][PATCH 2/8] mm: Speculative pagefault infrastructure Peter Zijlstra
2010-01-04 18:24 ` [RFC][PATCH 3/8] mm: Add vma sequence count Peter Zijlstra
2010-01-04 18:24 ` [RFC][PATCH 4/8] mm: RCU free vmas Peter Zijlstra
2010-01-05  2:43   ` Paul E. McKenney
2010-01-05  8:28     ` Peter Zijlstra
2010-01-05 16:05       ` Paul E. McKenney
2010-01-04 18:24 ` [RFC][PATCH 5/8] mm: Speculative pte_map_lock() Peter Zijlstra
2010-01-04 18:24 ` [RFC][PATCH 6/8] mm: handle_speculative_fault() Peter Zijlstra
2010-01-05  0:25   ` KAMEZAWA Hiroyuki
2010-01-05  3:13     ` Linus Torvalds
2010-01-05  8:17       ` Peter Zijlstra
2010-01-05  8:57       ` Peter Zijlstra
2010-01-05 15:34         ` Linus Torvalds
2010-01-05 15:40           ` Al Viro
2010-01-05 16:10             ` Linus Torvalds
2010-01-06 15:41               ` Peter Zijlstra
2010-01-05  9:37       ` Peter Zijlstra
2010-01-05 23:35         ` Linus Torvalds
2010-01-05  4:29     ` Minchan Kim
2010-01-05  4:43       ` KAMEZAWA Hiroyuki
2010-01-05  5:10         ` Linus Torvalds
2010-01-05  5:30           ` KAMEZAWA Hiroyuki
2010-01-05  7:39             ` KAMEZAWA Hiroyuki
2010-01-05 15:26               ` Linus Torvalds
2010-01-05 16:14                 ` Linus Torvalds
2010-01-05 17:25                   ` Andi Kleen
2010-01-05 17:47                     ` Christoph Lameter
2010-01-05 18:00                       ` Andi Kleen
2010-01-05 17:55                     ` Linus Torvalds
2010-01-05 18:13                       ` Christoph Lameter
2010-01-05 18:25                         ` Linus Torvalds
2010-01-05 18:46                           ` Christoph Lameter
2010-01-05 18:56                             ` Linus Torvalds
2010-01-05 19:15                               ` Christoph Lameter
2010-01-05 19:28                                 ` Linus Torvalds
2010-01-05 18:55                           ` Paul E. McKenney
2010-01-05 19:08                             ` Linus Torvalds
2010-01-05 19:23                               ` Paul E. McKenney
2010-01-05 20:29                           ` Peter Zijlstra
2010-01-05 20:46                             ` Linus Torvalds
2010-01-05 21:00                               ` Linus Torvalds
2010-01-05 23:29                             ` Paul E. McKenney
2010-01-06  0:22                 ` KAMEZAWA Hiroyuki
2010-01-06  1:37                   ` Linus Torvalds
2010-01-06  2:52                     ` KAMEZAWA Hiroyuki
2010-01-06  3:27                       ` Linus Torvalds
2010-01-06  3:56                         ` KAMEZAWA Hiroyuki
2010-01-06  4:20                           ` Linus Torvalds
2010-01-06  7:06                             ` KAMEZAWA Hiroyuki
2010-01-06  7:49                               ` Minchan Kim
2010-01-06  9:39                               ` Linus Torvalds
2010-01-07  1:00                                 ` KAMEZAWA Hiroyuki
2010-01-08 16:53                             ` Peter Zijlstra
2010-01-08 17:22                               ` Linus Torvalds
2010-01-08 17:43                                 ` Christoph Lameter
2010-01-08 17:52                                   ` Linus Torvalds
2010-01-08 18:33                                     ` Christoph Lameter
2010-01-08 18:46                                   ` Andi Kleen
2010-01-08 18:56                                     ` Christoph Lameter
2010-01-08 19:10                                       ` Andi Kleen
2010-01-08 19:11                                       ` Linus Torvalds
2010-01-08 19:28                                         ` Andi Kleen
2010-01-08 19:39                                           ` Linus Torvalds
2010-01-08 19:42                                             ` Linus Torvalds
2010-01-08 21:36                                   ` Linus Torvalds
2010-01-08 21:46                                     ` Christoph Lameter
2010-01-08 22:43                                       ` Linus Torvalds
2010-01-08 22:43                                       ` Linus Torvalds
2010-01-09 14:47                               ` Ed Tomlinson
2010-01-10  5:27                                 ` Nitin Gupta
2010-01-05 15:14             ` Christoph Lameter
2010-01-05  8:18           ` Peter Zijlstra
2010-01-05  6:00         ` Minchan Kim
2010-01-05  4:48       ` Linus Torvalds
2010-01-05  6:09         ` Minchan Kim
2010-01-05  6:09           ` KAMEZAWA Hiroyuki
2010-01-05  6:24             ` Minchan Kim
2010-01-05  8:35           ` Peter Zijlstra
2010-01-05 13:45   ` Arjan van de Ven
2010-01-05 14:15     ` Andi Kleen
2010-01-05 15:17     ` Christoph Lameter
2010-01-06  3:22       ` Arjan van de Ven
2010-01-07 16:11         ` Christoph Lameter
2010-01-07 16:19           ` Linus Torvalds
2010-01-07 16:31             ` Linus Torvalds [this message]
2010-01-07 16:34             ` Paul E. McKenney
2010-01-07 16:36             ` Christoph Lameter
2010-01-08  4:49               ` Arjan van de Ven
2010-01-08  5:00                 ` Linus Torvalds
2010-01-08 15:51                 ` Christoph Lameter
2010-01-09 15:55                   ` Arjan van de Ven
2010-01-07 17:22             ` Peter Zijlstra
2010-01-07 17:36               ` Linus Torvalds
2010-01-07 17:49                 ` Linus Torvalds
2010-01-07 18:00                   ` Peter Zijlstra
2010-01-07 18:15                     ` Linus Torvalds
2010-01-07 21:49                       ` Peter Zijlstra
2010-01-07 18:44                   ` Linus Torvalds
2010-01-07 19:20                     ` Paul E. McKenney
2010-01-07 20:06                       ` Linus Torvalds
2010-01-07 20:25                         ` Paul E. McKenney
2010-01-07 19:24                     ` Christoph Lameter
2010-01-07 20:08                       ` Linus Torvalds
2010-01-07 20:13                         ` Linus Torvalds
2010-01-07 21:44                     ` Peter Zijlstra
2010-01-07 22:33                       ` Linus Torvalds
2010-01-08  0:23                         ` KAMEZAWA Hiroyuki
2010-01-08  0:25                           ` KAMEZAWA Hiroyuki
2010-01-08  0:39                           ` Linus Torvalds
2010-01-08  0:41                             ` Linus Torvalds
2010-01-07 23:51                 ` Rik van Riel
2010-01-04 18:24 ` [RFC][PATCH 7/8] mm,x86: speculative pagefault support Peter Zijlstra
2010-01-04 18:24 ` [RFC][PATCH 8/8] mm: Optimize pte_map_lock() Peter Zijlstra
2010-01-04 21:41 ` [RFC][PATCH 0/8] Speculative pagefault -v3 Rik van Riel
2010-01-04 21:46   ` Peter Zijlstra
2010-01-04 23:20     ` Rik van Riel
2010-01-04 21:59   ` Christoph Lameter
2010-01-05  0:28     ` KAMEZAWA Hiroyuki
2010-01-05  2:26 ` Minchan Kim

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