netdev - Re: root_lock vs. device's TX lock

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Message-Id: <20111121.160428.284433780067739645.davem@davemloft.net>
Date:	Mon, 21 Nov 2011 16:04:28 -0500 (EST)
From:	David Miller <davem@...emloft.net>
To:	dave.taht@...il.com
Cc:	eric.dumazet@...il.com, therbert@...gle.com, netdev@...r.kernel.org
Subject: Re: root_lock vs. device's TX lock

From: Dave Taht <dave.taht@...il.com>
Date: Thu, 17 Nov 2011 19:19:58 +0100

> On Thu, Nov 17, 2011 at 6:26 PM, Eric Dumazet <eric.dumazet@...il.com> wrote:
>>
>> For complex Qdisc / tc setups (potentially touching a lot of cache
>> lines), we could eventually add a small ring buffer so that the cpu
>> doing the ndo_start_xmit() also queues the packets into Qdisc.
>>
>> This ringbuffer could use a lockless algo. (we currently use the
>> secondary 'busylock' to serialize other cpus, but each cpu calls qdisc
>> enqueue itself.)
> 
> I was thinking ringbuffering might also help in adding a 'grouper'
> abstraction to the dequeuing side.

I fully support the idea of batching between these different levels of
the TX path, but keep in mind that this is only really going to work
well for simple qdiscs.
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