netdev - Re: [RFC,PATCH] loopback: calls netif_receive_skb() instead of netif

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Message-ID: <20080227072041.GA4000@ff.dom.local>
Date:	Wed, 27 Feb 2008 07:20:41 +0000
From:	Jarek Poplawski <jarkao2@...il.com>
To:	David Miller <davem@...emloft.net>
Cc:	dada1@...mosbay.com, netdev@...r.kernel.org
Subject: Re: [RFC,PATCH] loopback: calls netif_receive_skb() instead of
	netif_rx()

On 27-02-2008 03:21, David Miller wrote:
> From: Eric Dumazet <dada1@...mosbay.com>
> Date: Thu, 21 Feb 2008 19:51:52 +0100
> 
>> Following patch directly calls netif_receive_skb() and avoids lot of 
>> atomic operations.
>> (atomic_inc(&dev->refcnt), set_and_set_bit(NAPI_STATE_SCHED, &n->state), ...
>>   atomic_dec(&dev->refcnt)...), cache line ping-pongs on device refcnt, 
>> but also softirq overhead.
>>
>> This gives a nice boost on tbench for example (5 % on my machine)
> 
> My only concern is stack usage.
...

I wonder why overloading with net processing is no concern here?
There would be no napi control around this  netif_receive_skb().

Another concern might be a code which depends on softirq context
here (unless it was checked already)?

Regards,
Jarek P.
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