Re: [Qemu-devel] [PATCH 2/2] [SLIRP] Delayed IP packets

[Fabien Chouteau]

On 27/07/2011 11:30, Jan Kiszka wrote:
> On 2011-07-26 18:21, Fabien Chouteau wrote:
>> In the current implementation, if Slirp tries to send an IP packet to a 
>> client
>> with an unknown hardware address, the packet is simply dropped and an ARP
>> request is sent (if_encap in slirp/slirp.c).
>>
>> This patch adds a list of delayed IP packets to handle such cases. If the
>> hardware address is unknown, Slirp inserts the packet in delayed list and 
>> sends
>> an ARP request. Each time the ARP table is updated Slirp retries to send the
>> packet.
>
> Haven't looked at details yet, just two general thoughts so far:
>
> We already have queues for outgoing packets, why can't we reuse that
> infrastructure? That would also avoid additional memory allocations.
> Delayed packets should be requeued at the end and only one attempt to
> send them should be performed per queue flush.

Sure, I didn't know about these queues. Where are they implemented?

>
> I think we need some timeout for the delayed packets. If invalid or
> non-reactive clients are addressed, we will otherwise pile them up until
> qemu terminates, right?

Yes that's a good idea.

Regards,

-- 
Fabien Chouteau