netdev - Re: gso: Handle new frag_list of frags GRO packets

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Message-ID: <20131113012920.GA27897@gondor.apana.org.au>
Date:	Wed, 13 Nov 2013 09:29:20 +0800
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Ben Hutchings <bhutchings@...arflare.com>,
	David Miller <davem@...emloft.net>,
	christoph.paasch@...ouvain.be, netdev@...r.kernel.org,
	hkchu@...gle.com, mwdalton@...gle.com
Subject: Re: gso: Handle new frag_list of frags GRO packets

On Tue, Nov 12, 2013 at 05:13:43PM -0800, Eric Dumazet wrote:
>
> Note this pskb_trim() will reallocate/copy nskb head completely, since
> nskb is a clone. (And increment page counts of frags, then eventually
> decrement them)
> 
> I tested this patch one 'router', and it seems fine, although we consume
> ~90% more cpu doing the skb_segment() than not doing it.

I presume this is on a NIC that produces completely linear packets?
I wonder what happens if we don't convert head_frag to frags and just
use frag_lists like we used to?

Thanks,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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