Subject: Re: [net-next 09/14] igb: Report L4 Rx hash via skb->l4_rxhash

From: Alexander Duyck <[email-masked]>
Date: Thu, 17 Jan 2013 09:23:10 -0800

On 01/17/2013 09:14 AM, Eric Dumazet wrote:
> On Thu, 2013-01-17 at 09:07 -0800, Alexander Duyck wrote:
> 
>> Isn't the same true of TCP?  I believe STT is intended to run over the
>> TCP protocol, or am I getting ahead of myself since STT is not supported
>> by the kernel?
>>
> 
> probably ;)
> 
>>> Also, is IGB really using the ports in the rss for UDP packets ?
>>
>> Not by default.  The default is to only hash on the IP header for UDP
>> packets.
>>
>> As such the default would only be setting the l4_rxhash on TCP frames
>> only.  The user would have to specifically request L4 port hashing for
>> UDP via the "ethtool -N" command for configuring rx-flow-hash.
> 
> So you should rewrite this patch ?
> 
> Or have I missed something ?

I'm probably going to scrap it.  No point in rewriting it.

I has assumed that there were other uses for the l4_rxhash value.  If
all it is meant for is to indicate that the inner header of a tunnel was
used to compute the hash then there isn't much point to adding support
for this in igb/ixgbe since they don't support any inner header hashing.

It might add value at some point to rename the l4_rxhash flag to
something else though since it seems like there are now tunnels that are
encapsulated inside of l4 headers and it is going to get confusing.

Thanks,

Alex