Hi,

Thanks for the patch. I almost dare not confess that I don't know which 
version to apply to. I tried 3 different ones (2.6.19-r5-gentoo, 
2.6.20.1 and 2.6.21-rc4), but in the best case at least two hunks 
failed. Nevertheless, I applied the patches manually. In each case, UDP 
stopped working. I guess, you checked the patch and worked. I don't 
think I made a mistake in the manual copy, and it seems unlikely that 
your patch interfered with other parallel changes in the kernel - but, 
I'm just guessing ...
I think, I'd better send you the spec and code, as you suggested that 
first we have a common understanding of the issue. I must have failed in 
passing the point. I'm removing irrelevant stuff, and I send it to you 
as soon as I can (sorry for my long delays).

thx a lot,
Zacco

Eric Dumazet wrote:

Eric Dumazet a écrit :

quoted

Currently, udp_hash[UDP_HTABLE_SIZE] is using a hash function based 
on dport number only.

In your case, as you use a single port value, all sockets are in a 
single slot of this hash table :
To find the good socket, __udp4_lib_lookup() has to search in a list 
with thousands of elements. Not that good, isnt it ? :(

In case you want to try, here is a patch that could help you :)

[PATCH] INET : IPV4 UDP lookups converted to a 2 pass algo

Some people want to have many UDP sockets, binded to a single port but 
many different addresses. We currently hash all those sockets into a 
single chain. Processing of incoming packets is very expensive, 
because the whole chain must be examined to find the best match.

I chose in this patch to hash UDP sockets with a hash function that 
take into account both their port number and address : This has a 
drawback because we need two lookups : one with a given address, one 
with a wildcard (null) address.

Signed-off-by: Eric Dumazet <redacted>