Date: Fri, 21 Nov 2008 01:05:08 -0800 (PST)
Message-Id: <20081121.010508.40225532.davem@davemloft.net>
To: dada1@cosmosbay.com
Cc: mingo@elte.hu, cl@linux-foundation.org, rjw@sisk.pl,
       linux-kernel@vger.kernel.org, kernel-testers@vger.kernel.org,
       efault@gmx.de, a.p.zijlstra@chello.nl
Subject: Re: [Bug #11308] tbench regression on each kernel release from
 2.6.22 -&gt; 2.6.28
From: David Miller <davem@davemloft.net>
In-Reply-To: <49267694.1030506@cosmosbay.com>
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	<20081121083044.GL16242@elte.hu>
	<49267694.1030506@cosmosbay.com>
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From: Eric Dumazet <dada1@cosmosbay.com>
Date: Fri, 21 Nov 2008 09:51:32 +0100

> Now, I wish sockets and pipes not going through dcache, not tbench affair
> of course but real workloads...
> 
> running 8 processes on a 8 way machine doing a 
> 
> for (;;)
> 	close(socket(AF_INET, SOCK_STREAM, 0));
> 
> is slow as hell, we hit so many contended cache lines ...
> 
> ticket spin locks are slower in this case (dcache_lock for example
> is taken twice when we allocate a socket(), once in d_alloc(), another one
> in d_instantiate())

As you of course know, this used to be a ton worse.  At least now
these things are unhashed. :)

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