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From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Eric Dumazet <dada1@cosmosbay.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Dave Jones <davej@redhat.com>, Ulrich Drepper <drepper@gmail.com>,
	Ingo Molnar <mingo@elte.hu>, Andi Kleen <ak@suse.de>,
	Ravikiran G Thirumalai <kiran@scalex86.org>,
	"Shai Fultheim (Shai@scalex86.org)" <shai@scalex86.org>,
	pravin b shelar <pravin.shelar@calsoftinc.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH, take4] FUTEX : new PRIVATE futexes
Date: Thu, 12 Apr 2007 11:57:02 +1000	[thread overview]
Message-ID: <461D91EE.6020404@yahoo.com.au> (raw)
In-Reply-To: <20070411113525.baf8deb0.dada1@cosmosbay.com>

Eric Dumazet wrote:
> On Wed, 11 Apr 2007 19:23:26 +1000
> Nick Piggin <nickpiggin@yahoo.com.au> wrote:

>>>As this external thing certainly is not doing the check itself, to be on the safe side we should enforce it in get_futex_key(). I agree with you : If we want to maximize performance, we could say : The check *must* be done by the caller.
>>
>>Well we _control_ the API, so let's make it as clean and performant as possible
>>from the start.
> 
> 
> Take a look at do_futex().
> Adding checks in callers just increase code size. I tried this got only bad results.
> This would speedup only the slow path (ie when some user code want to give us non aligned addrs)
> A single factorized check is cleaner and not slower, since we reduce icache pressure.

1 extra check versus all that additional argument passing? I don't think it
is conclusive.

-- 
SUSE Labs, Novell Inc.

  reply	other threads:[~2007-04-12  1:57 UTC|newest]

Thread overview: 78+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-08-08  7:07 [RFC] NUMA futex hashing Ravikiran G Thirumalai
2006-08-08  9:14 ` Eric Dumazet
2006-08-08 20:31   ` Ravikiran G Thirumalai
2006-08-08  9:37 ` Jes Sorensen
2006-08-08  9:58   ` Andi Kleen
2006-08-08 10:07     ` Jes Sorensen
2006-08-08  9:57 ` Andi Kleen
2006-08-08 10:10   ` Eric Dumazet
2006-08-08 10:36     ` Andi Kleen
2006-08-08 12:29       ` Eric Dumazet
2006-08-08 12:47         ` Andi Kleen
2006-08-08 12:57           ` Eric Dumazet
2006-08-08 14:39             ` Ulrich Drepper
2006-08-08 15:11               ` Nick Piggin
2006-08-08 15:36                 ` Ulrich Drepper
2006-08-08 16:22                   ` Nick Piggin
2006-08-08 16:26                     ` Nick Piggin
2006-08-08 16:49                     ` Ulrich Drepper
2006-08-08 16:08                 ` Eric Dumazet
2006-08-08 16:34                   ` Nick Piggin
2006-08-08 16:49                     ` Eric Dumazet
2006-08-08 16:59                       ` Eric Dumazet
2006-08-09  1:56                       ` Nick Piggin
2006-08-08 16:58                   ` Ulrich Drepper
2006-08-08 17:08                     ` Eric Dumazet
2006-08-09  1:58                     ` Nick Piggin
2006-08-09  6:26                       ` Eric Dumazet
2006-08-09  6:43                         ` Eric Dumazet
2007-03-15 19:10                           ` [PATCH 0/3] FUTEX : new PRIVATE futexes, SMP and NUMA improvements Eric Dumazet
2007-03-15 20:15                             ` Nick Piggin
2007-03-16  8:05                             ` Peter Zijlstra
2007-03-16  9:30                               ` Eric Dumazet
2007-03-16 10:10                                 ` Peter Zijlstra
2007-03-16 10:30                                   ` Eric Dumazet
2007-03-16 10:36                                     ` Peter Zijlstra
2007-04-04  7:16                             ` Ulrich Drepper
2007-04-05 17:49                               ` [PATCH] FUTEX : new PRIVATE futexes Eric Dumazet
2007-04-05 20:43                                 ` Ulrich Drepper
2007-04-06  1:19                                 ` Nick Piggin
2007-04-06  5:53                                   ` Eric Dumazet
2007-04-06 11:50                                     ` Nick Piggin
2007-04-06  6:05                                   ` Hugh Dickins
2007-04-06 17:41                                     ` Jan Engelhardt
2007-04-06 12:26                                 ` Shared futexes (was [PATCH] FUTEX : new PRIVATE futexes) Peter Zijlstra
2007-04-06 13:02                                   ` Hugh Dickins
2007-04-06 13:15                                     ` Peter Zijlstra
2007-04-06 13:15                                     ` Nick Piggin
2007-04-06 13:22                                       ` Peter Zijlstra
2007-04-06 13:40                                         ` Nick Piggin
2007-04-06 12:31                                 ` [PATCH] FUTEX : new PRIVATE futexes Peter Zijlstra
2007-04-07  8:43                                 ` [PATCH, take4] " Eric Dumazet
2007-04-07  9:30                                   ` Nick Piggin
2007-04-07 10:00                                     ` Eric Dumazet
2007-04-11  7:22                                       ` Nick Piggin
2007-04-11  8:14                                         ` Eric Dumazet
2007-04-11  9:23                                           ` Nick Piggin
2007-04-11  9:30                                             ` Pierre Peiffer
2007-04-11  9:39                                               ` Nick Piggin
2007-04-11  9:40                                                 ` Nick Piggin
2007-04-11  9:35                                             ` Eric Dumazet
2007-04-12  1:57                                               ` Nick Piggin [this message]
2007-04-07 11:18                                   ` Jakub Jelinek
2007-04-07 11:54                                     ` Eric Dumazet
2007-04-07 16:40                                       ` Ulrich Drepper
2007-04-07 22:15                                   ` Andrew Morton
2007-04-10  9:21                                     ` Eric Dumazet
2007-04-11  9:19                                   ` [PATCH, take5] " Eric Dumazet
2007-04-11 12:23                                     ` Rusty Russell
2007-04-26 12:55                                     ` [PATCH, take6] " Eric Dumazet
2007-04-26 13:35                                       ` Pierre Peiffer
2007-03-15 19:13                           ` [PATCH 1/3] FUTEX : introduce PROCESS_PRIVATE semantic Eric Dumazet
2007-03-15 19:16                           ` [PATCH 2/3] FUTEX : introduce private hashtables Eric Dumazet
2007-03-15 20:25                             ` Nick Piggin
2007-03-15 21:09                               ` Ulrich Drepper
2007-03-15 21:29                                 ` Nick Piggin
2007-03-15 22:59                               ` William Lee Irwin III
2007-03-15 19:20                           ` [PATCH 3/3] FUTEX : NUMA friendly global hashtable Eric Dumazet
2006-08-09  0:13     ` [RFC] NUMA futex hashing Ravikiran G Thirumalai

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