netdev - Re: [RFC] [PATCH] Don't run __qdisc

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Date:	Wed, 29 Jul 2009 20:30:41 +0800
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	Jarek Poplawski <jarkao2@...il.com>
Cc:	David Miller <davem@...emloft.net>, krkumar2@...ibm.com,
	netdev@...r.kernel.org
Subject: Re: [RFC] [PATCH] Don't run __qdisc_run() on a stopped TX queue

On Wed, Jul 29, 2009 at 11:26:14AM +0000, Jarek Poplawski wrote:
>
> If you mean the tx lock there should be no "real" contention: only
> one waiter max. qdisc lock's contention might be higher, but it's
> use (during contention) better: enqueue + dequeue together instead
> of doing it separately.

Hmm, you will have contention if they're both transmitting a
single flow which must always go into a single physical queue.

So you'll have two CPUs doing the work of a single CPU, with one
of them always spinning on the TX lock.

Cheers,
-- 
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Email: Herbert Xu ~{PmV>HI~} <herbert@...dor.apana.org.au>
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