netdev - Re: Add NAPI support to ll

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Date:	Tue, 19 Apr 2011 13:25:25 +0100
From:	Ben Hutchings <bhutchings@...arflare.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	monstr@...str.eu, netdev@...r.kernel.org
Subject: Re: Add NAPI support to ll_temac driver

On Tue, 2011-04-19 at 12:43 +0200, Eric Dumazet wrote:
[...]
> One possible way to get better performance is to change driver to
> allocate skbs only right before calling netif_rx(), so that you dont
> have to access cold sk_buff data twice (once when allocating skb and put
> it in ring buffer, a second time when receiving frame)
>
> drivers/net/niu.c is a good example for this (NAPI + netdev_alloc_skb()
> just in time + pull in skbhead only first cache line of packet)
[...]

If the hardware can do RX checksumming (it's not clear) then the driver
should pass the paged buffers into GRO and that will take care of skb
allocation as necessary.

Ben.

-- 
Ben Hutchings, Senior Software Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.

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