linux-kernel - Re: [Bug #11308] tbench regression on each kernel release from 2.6.22 -> 2.6.28

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Message-Id: <20081121.010508.40225532.davem@davemloft.net>
Date:	Fri, 21 Nov 2008 01:05:08 -0800 (PST)
From:	David Miller <davem@...emloft.net>
To:	dada1@...mosbay.com
Cc:	mingo@...e.hu, cl@...ux-foundation.org, rjw@...k.pl,
	linux-kernel@...r.kernel.org, kernel-testers@...r.kernel.org,
	efault@....de, a.p.zijlstra@...llo.nl
Subject: Re: [Bug #11308] tbench regression on each kernel release from
 2.6.22 -&gt; 2.6.28

From: Eric Dumazet <dada1@...mosbay.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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