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From: Christoph Lameter <cl@linux-foundation.org>
To: Arjan van de Ven <arjan@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.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: Fri, 8 Jan 2010 09:51:49 -0600 (CST)	[thread overview]
Message-ID: <alpine.DEB.2.00.1001080946390.23727@router.home> (raw)
In-Reply-To: <20100107204940.253ed753@infradead.org>

On Thu, 7 Jan 2010, Arjan van de Ven wrote:

> if an app has to change because our kernel sucks (for no good reason),
> "change the app" really is the lame type of answer.

We are changing apps all of the time here to reduce the number of system
calls. Any system call usually requires context switching, scheduling
activities etc. Evil effects if you want the processor for computation
and are sensitive to cpu caching effects. It is good to reduce the number
of system calls as much as possible.

System calls are at best placed to affect the largest memory
possible in a given context and be avoided in loops.

--
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  parent reply	other threads:[~2010-01-08 15:52 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
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 [this message]
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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