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From: Herbert Xu <herbert@gondor.apana.org.au>
To: David Miller <davem@davemloft.net>
Cc: dada1@cosmosbay.com, jarkao2@gmail.com, vernux@us.ibm.com,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-rt-users@vger.kernel.org
Subject: Re: High contention on the sk_buff_head.lock
Date: Thu, 2 Apr 2009 22:13:42 +0800	[thread overview]
Message-ID: <20090402141342.GA377@gondor.apana.org.au> (raw)
In-Reply-To: <20090323.013749.122944803.davem@davemloft.net>

David Miller <davem@davemloft.net> wrote:
> From: Eric Dumazet <dada1@cosmosbay.com>
> Date: Mon, 23 Mar 2009 09:32:39 +0100
> 
>> I dont understand, doesnt it defeat the ticket spinlock thing and fairness ?
>> 
>> Thread doing __qdisc_run() already owns the __QDISC_STATE_RUNNING bit.
> 
> Right.
> 
> Remember, the way this is designed is that if there is a busy
> cpu taking packets out of the queue and putting them into the
> device then other cpus will simply add to the queue and immediately
> return.  This effectively keeps the queue running there processing
> all the new work that other cpus are adding to the qdisc.
> 
> Those other cpus make these decisions by looking at that
> __QDISC_STATE_RUNNING bit, which the queue runner grabs before
> it does any work.

Come on guys, if this lock is a problem. go out and buy a proper
NIC that supports multiequeue TX!

Cheers,
-- 
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

  parent reply	other threads:[~2009-04-02 14:14 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-03-18 17:24 High contention on the sk_buff_head.lock Vernon Mauery
2009-03-18 19:07 ` Eric Dumazet
2009-03-18 20:17   ` Vernon Mauery
2009-03-20 23:29     ` Jarek Poplawski
2009-03-23  8:32       ` Eric Dumazet
2009-03-23  8:32         ` Eric Dumazet
2009-03-23  8:37         ` David Miller
2009-03-23  8:50           ` Jarek Poplawski
2009-04-02 14:13           ` Herbert Xu [this message]
2009-04-02 14:15             ` Herbert Xu
2009-03-18 20:54 ` Andi Kleen
2009-03-18 21:03   ` David Miller
2009-03-18 21:10     ` Vernon Mauery
2009-03-18 21:38       ` David Miller
2009-03-18 21:49         ` Vernon Mauery
2009-03-19  1:02           ` David Miller
2009-03-18 21:54         ` Gregory Haskins
2009-03-19  1:03           ` David Miller
2009-03-19  1:13             ` Sven-Thorsten Dietrich
2009-03-19  1:17               ` David Miller
2009-03-19  1:43                 ` Sven-Thorsten Dietrich
2009-03-19  1:54                   ` David Miller
2009-03-19  5:49                     ` Eric Dumazet
2009-03-19  5:49                       ` Eric Dumazet
2009-03-19  5:58                       ` David Miller
2009-03-19 14:04                         ` [PATCH] net: reorder struct Qdisc for better SMP performance Eric Dumazet
2009-03-19 14:04                           ` Eric Dumazet
2009-03-20  8:33                           ` David Miller
2009-03-19 13:45                   ` High contention on the sk_buff_head.lock Andi Kleen
2009-03-19  3:48             ` Gregory Haskins
2009-03-19  5:38               ` David Miller
2009-03-19 12:42                 ` Gregory Haskins
2009-03-19 20:52                   ` David Miller
2009-03-19 12:50             ` Peter W. Morreale
2009-03-19  7:15           ` Evgeniy Polyakov
2009-03-18 21:07   ` Vernon Mauery
2009-03-18 21:45     ` Eilon Greenstein
2009-03-18 21:51       ` Vernon Mauery
2009-03-18 21:59         ` Andi Kleen
2009-03-18 22:19           ` Rick Jones
2009-03-19 12:59   ` Peter W. Morreale
2009-03-19 13:36     ` Peter W. Morreale
2009-03-19 13:46     ` Andi Kleen

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