netdev - Re: [PATCH net-next V2 1/3] net: Add GRO support for UDP encapsulating protocols

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Date:	Tue, 7 Jan 2014 22:19:10 +0200
From:	Or Gerlitz <or.gerlitz@...il.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Or Gerlitz <ogerlitz@...lanox.com>, Jerry Chu <hkchu@...gle.com>,
	Eric Dumazet <edumazet@...gle.com>,
	Herbert Xu <herbert@...dor.apana.org.au>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	David Miller <davem@...emloft.net>,
	Yan Burman <yanb@...lanox.com>,
	Shlomo Pongratz <shlomop@...lanox.com>
Subject: Re: [PATCH net-next V2 1/3] net: Add GRO support for UDP
 encapsulating protocols

On Tue, Jan 7, 2014 at 6:33 PM, Eric Dumazet <eric.dumazet@...il.com> wrote:
> On Tue, 2014-01-07 at 17:29 +0200, Or Gerlitz wrote:
>>
>> +
>> +#define MAX_UDP_PORT (1 << 16)
>> +extern const struct net_offload __rcu *udp_offloads[MAX_UDP_PORT];
>
> Thats 512 KB of memory.
> This will greatly impact forwarding performance of UDP packets with
> random ports, and will increase kernel memory size for embedded devices.

Re forwarding, are you referring to the case where the forwarded
packets are encapsulated? packets which are not encapusalted will be
flushed in the gro receive handler (this went out by mistake in V2 but
exists in V1)  if skb->encapsulation isn't set.

As for encapsulated packets, when you say random ports, are you
referring to a router which has multiple udp encapsulating protocols
where each uses different udp port? for this case and also to reduce
the memory footprint, we can use lookup in a list as done for the L2
protocols gro handlers in the list_for_each loop of dev_gro_receive(),
makes sense?
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