linux-kernel - Re: Why Semaphore Hardware-Dependent?

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Message-ID: <20060829191015.GL18092@kvack.org>
Date:	Tue, 29 Aug 2006 15:10:15 -0400
From:	Benjamin LaHaise <bcrl@...ck.org>
To:	Andi Kleen <ak@...e.de>
Cc:	David Howells <dhowells@...hat.com>,
	Nick Piggin <nickpiggin@...oo.com.au>,
	Arjan van de Ven <arjan@...radead.org>,
	Dong Feng <middle.fengdong@...il.com>,
	Paul Mackerras <paulus@...ba.org>,
	Christoph Lameter <clameter@....com>,
	linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org
Subject: Re: Why Semaphore Hardware-Dependent?

On Tue, Aug 29, 2006 at 12:56:54PM +0200, Andi Kleen wrote:
> We've completely given up these kinds of micro optimization for spinlocks,
> which are 1000x as critical as rwsems.  And nobody was able to benchmark
> a difference.

That is false.  It shows up on things like netperf on the P4, or the AF_UNIX 
component of lmbench.

		-ben
-- 
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