netdev - Re: Softirqs without captured packets

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Date:	Fri, 22 Feb 2013 06:11:21 -0800
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Javier Domingo <javierdo1@...il.com>
Cc:	David Miller <davem@...emloft.net>, netdev@...r.kernel.org
Subject: Re: Softirqs without captured packets

On Fri, 2013-02-22 at 10:32 +0100, Javier Domingo wrote:
> Which is the reason for that in the poll function, not only some
> drivers have that tx completion (I suppose it is to free resources),
> but also to send packets in that routine?
> 
> In e1000e, I have found that it frees resources used in tx, with the
> e1000_clean_tx_irq, and also, although the tx completion is first, it
> executes the rx routine.
> 
> On the other hand, tg3 driver not only does the tx resources free but
> also sends packets in that time, and may return from the poll thought
> it might not have done rx work in the net_rx_action routine.
> 
> Why is this like that? I mean, why all the tx is done *before* the rx
> thread, thought it may not do any rx work (in tg3) ?

To free memory, so that rx handler gets more chance to be able to
allocate memory, and reuse memory already hot in cpu caches.



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