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From: Andi Kleen <ak@suse.de>
To: Hans Boehm <Hans.Boehm@hp.com>
Cc: Christoph Lameter <clameter@sgi.com>,
	Zoltan Menyhart <Zoltan.Menyhart@bull.net>,
	"Grundler, Grant G" <grant.grundler@hp.com>,
	"Chen, Kenneth W" <kenneth.w.chen@intel.com>,
	akpm@osdl.org, linux-kernel@vger.kernel.org,
	linux-ia64@vger.kernel.org
Subject: Re: Synchronizing Bit operations V2
Date: Fri, 31 Mar 2006 16:37:33 +0000	[thread overview]
Message-ID: <200603311837.34477.ak@suse.de> (raw)
In-Reply-To: <Pine.GHP.4.58.0603310808190.28478@tomil.hpl.hp.com>

On Friday 31 March 2006 18:22, Hans Boehm wrote:

> My impression is that approach (1) tends not to stick, since it involves
> a substantial performance hit on architectures on which the fence is
> not implicitly included in atomic operations.  Those include Itanium and
> PowerPC.

At least the PPC people are eating the overhead because back when they
didn't they had a long string of subtle powerpc only bugs caused by that

It's a stability/maintainability vs performance issue. I doubt the 
performance advantage would be worth the additional work. I guess
with the engineering time you would need to spend getting all this right
you could do much more fruitful optimizations.

-Andi

WARNING: multiple messages have this Message-ID (diff)
From: Andi Kleen <ak@suse.de>
To: Hans Boehm <Hans.Boehm@hp.com>
Cc: Christoph Lameter <clameter@sgi.com>,
	Zoltan Menyhart <Zoltan.Menyhart@bull.net>,
	"Grundler, Grant G" <grant.grundler@hp.com>,
	"Chen, Kenneth W" <kenneth.w.chen@intel.com>,
	akpm@osdl.org, linux-kernel@vger.kernel.org,
	linux-ia64@vger.kernel.org
Subject: Re: Synchronizing Bit operations V2
Date: Fri, 31 Mar 2006 18:37:33 +0200	[thread overview]
Message-ID: <200603311837.34477.ak@suse.de> (raw)
In-Reply-To: <Pine.GHP.4.58.0603310808190.28478@tomil.hpl.hp.com>

On Friday 31 March 2006 18:22, Hans Boehm wrote:

> My impression is that approach (1) tends not to stick, since it involves
> a substantial performance hit on architectures on which the fence is
> not implicitly included in atomic operations.  Those include Itanium and
> PowerPC.

At least the PPC people are eating the overhead because back when they
didn't they had a long string of subtle powerpc only bugs caused by that

It's a stability/maintainability vs performance issue. I doubt the 
performance advantage would be worth the additional work. I guess
with the engineering time you would need to spend getting all this right
you could do much more fruitful optimizations.

-Andi

  reply	other threads:[~2006-03-31 16:37 UTC|newest]

Thread overview: 124+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-03-30 21:02 Bit operations with the ability to specify a synchronization mode Christoph Lameter
2006-03-30 21:02 ` Christoph Lameter
2006-03-31  0:18 ` Synchronizing Bit operations V2 Christoph Lameter
2006-03-31  0:18   ` Christoph Lameter
2006-03-31  0:39   ` Chen, Kenneth W
2006-03-31  0:39     ` Chen, Kenneth W
2006-03-31  0:42     ` Christoph Lameter
2006-03-31  0:42       ` Christoph Lameter
2006-03-31  0:45     ` Christoph Lameter
2006-03-31  0:45       ` Christoph Lameter
2006-03-31  0:42   ` David Mosberger-Tang
2006-03-31  0:42     ` David Mosberger-Tang
2006-03-31  0:49     ` Christoph Lameter
2006-03-31  0:49       ` Christoph Lameter
2006-03-31  6:10     ` Chris Wright
2006-03-31  6:10       ` Chris Wright
2006-03-31  0:44   ` Nick Piggin
2006-03-31  0:44     ` Nick Piggin
2006-03-31  3:28     ` Christoph Lameter
2006-03-31  3:28       ` Christoph Lameter
2006-03-31  4:12       ` Nick Piggin
2006-03-31  4:12         ` Nick Piggin
2006-03-31 17:43         ` Christoph Lameter
2006-03-31 17:43           ` Christoph Lameter
2006-04-01  2:56           ` Nick Piggin
2006-04-01  2:56             ` Nick Piggin
2006-03-31  0:50   ` Chen, Kenneth W
2006-03-31  0:50     ` Chen, Kenneth W
2006-03-31  0:51     ` Christoph Lameter
2006-03-31  0:51       ` Christoph Lameter
2006-03-31  0:53   ` Chen, Kenneth W
2006-03-31  0:53     ` Chen, Kenneth W
2006-03-31  0:55     ` Christoph Lameter
2006-03-31  0:55       ` Christoph Lameter
2006-03-31  0:56   ` Luck, Tony
2006-03-31  0:56     ` Luck, Tony
2006-03-31  0:58     ` Christoph Lameter
2006-03-31  0:58       ` Christoph Lameter
2006-04-02  7:59       ` Russell King
2006-04-02  7:59         ` Russell King
2006-03-31  0:59   ` Chen, Kenneth W
2006-03-31  0:59     ` Chen, Kenneth W
2006-03-31  1:09     ` Christoph Lameter
2006-03-31  1:09       ` Christoph Lameter
2006-03-31  1:04   ` Chen, Kenneth W
2006-03-31  1:04     ` Chen, Kenneth W
2006-03-31  1:13     ` Christoph Lameter
2006-03-31  1:13       ` Christoph Lameter
2006-03-31  1:13   ` Chen, Kenneth W
2006-03-31  1:13     ` Chen, Kenneth W
2006-03-31  1:29   ` Chen, Kenneth W
2006-03-31  1:29     ` Chen, Kenneth W
2006-03-31  1:37     ` Christoph Lameter
2006-03-31  1:37       ` Christoph Lameter
2006-03-31  1:33   ` linux
2006-03-31  1:33     ` linux
2006-03-31  1:40     ` Christoph Lameter
2006-03-31  1:40       ` Christoph Lameter
2006-03-31  2:35   ` Chen, Kenneth W
2006-03-31  2:35     ` Chen, Kenneth W
2006-03-31  2:37     ` Christoph Lameter
2006-03-31  2:37       ` Christoph Lameter
2006-03-31  2:45   ` Chen, Kenneth W
2006-03-31  2:45     ` Chen, Kenneth W
2006-03-31  2:53     ` Nick Piggin
2006-03-31  2:53       ` Nick Piggin
2006-03-31  3:01     ` Christoph Lameter
2006-03-31  3:01       ` Christoph Lameter
2006-03-31  2:51   ` Chen, Kenneth W
2006-03-31  2:51     ` Chen, Kenneth W
2006-03-31  2:55     ` Christoph Lameter
2006-03-31  2:55       ` Christoph Lameter
2006-03-31  3:02   ` Chen, Kenneth W
2006-03-31  3:02     ` Chen, Kenneth W
2006-03-31  3:08     ` Christoph Lameter
2006-03-31  3:08       ` Christoph Lameter
2006-03-31  3:10   ` Chen, Kenneth W
2006-03-31  3:10     ` Chen, Kenneth W
2006-03-31  3:12     ` Christoph Lameter
2006-03-31  3:12       ` Christoph Lameter
2006-03-31  3:11   ` Chen, Kenneth W
2006-03-31  3:11     ` Chen, Kenneth W
2006-03-31  3:14   ` Chen, Kenneth W
2006-03-31  3:14     ` Chen, Kenneth W
2006-03-31  3:20     ` Christoph Lameter
2006-03-31  3:20       ` Christoph Lameter
2006-03-31  3:17   ` Chen, Kenneth W
2006-03-31  3:17     ` Chen, Kenneth W
2006-03-31  3:23   ` Chen, Kenneth W
2006-03-31  3:23     ` Chen, Kenneth W
2006-03-31  3:37   ` Chen, Kenneth W
2006-03-31  3:37     ` Chen, Kenneth W
2006-03-31  6:15   ` Chen, Kenneth W
2006-03-31  6:15     ` Chen, Kenneth W
2006-03-31  7:34     ` Nick Piggin
2006-03-31  7:34       ` Nick Piggin
2006-03-31 13:28   ` Andi Kleen
2006-03-31 13:28     ` Andi Kleen
2006-03-31 16:22     ` Hans Boehm
2006-03-31 16:22       ` Hans Boehm
2006-03-31 16:37       ` Andi Kleen [this message]
2006-03-31 16:37         ` Andi Kleen
2006-03-31 17:46         ` Christoph Lameter
2006-03-31 17:46           ` Christoph Lameter
2006-03-31 17:45     ` Christoph Lameter
2006-03-31 17:45       ` Christoph Lameter
2006-03-31 17:48       ` Andi Kleen
2006-03-31 17:48         ` Andi Kleen
2006-03-31 17:56         ` Christoph Lameter
2006-03-31 17:56           ` Christoph Lameter
2006-04-02  7:54           ` Russell King
2006-04-02  7:54             ` Russell King
2006-03-31 18:57   ` Chen, Kenneth W
2006-03-31 18:57     ` Chen, Kenneth W
2006-03-31 19:41   ` Chen, Kenneth W
2006-03-31 19:41     ` Chen, Kenneth W
2006-03-31 21:15     ` Christoph Lameter
2006-03-31 21:15       ` Christoph Lameter
2006-03-31 21:24   ` Chen, Kenneth W
2006-03-31 21:24     ` Chen, Kenneth W
2006-03-31 21:28     ` Christoph Lameter
2006-03-31 21:28       ` Christoph Lameter
2006-04-01  2:16       ` Nick Piggin
2006-04-01  2:16         ` Nick Piggin

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