From: David Miller <davem@davemloft.net>
To: dada1@cosmosbay.com
Cc: 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: Mon, 23 Mar 2009 01:37:49 -0700 (PDT) [thread overview]
Message-ID: <20090323.013749.122944803.davem@davemloft.net> (raw)
In-Reply-To: <49C74927.7020008@cosmosbay.com>
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.
next prev parent reply other threads:[~2009-03-23 8:38 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-03-18 17:24 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 8:37 ` David Miller [this message]
2009-03-23 8:50 ` Jarek Poplawski
2009-04-02 14:13 ` Herbert Xu
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 5:58 ` David Miller
2009-03-19 14:04 ` [PATCH] net: reorder struct Qdisc for better SMP performance 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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