Re: [PATCH] sky2: rx hash offload

[Eric Dumazet <eric.dumazet@gmail.com>]

Le lundi 05 avril 2010 à 08:48 -0700, Stephen Hemminger a écrit :
> Marvell Yukon 2 hardware supports hardware receive hash calculation.
> Now that Receive Packet Steering is available, add support
> to enable it.
> 
> Note: still experimental, tested on only a few variants.
> No performance testing has been done.
> 
> Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
> 
> ---
>  drivers/net/sky2.c |   75 +++++++++++++++++++++++++++++++++++++++++++++++++++--
>  drivers/net/sky2.h |   23 ++++++++++++++++
>  2 files changed, 96 insertions(+), 2 deletions(-)

I am wondering if introducing hardware computed rxhash wouldnt force us
to clear rxhash in several paths (tunneling...), so that we perform a
software recompute after decapsulation, to enable RFS

Not mandatory but recommended I would say...

diff --git a/net/ipv4/ipip.c b/net/ipv4/ipip.c
index 2f302d3..3f0aba4 100644
--- a/net/ipv4/ipip.c
+++ b/net/ipv4/ipip.c
@@ -379,6 +379,7 @@ static int ipip_rcv(struct sk_buff *skb)
 		skb_dst_drop(skb);
 		nf_reset(skb);
 		ipip_ecn_decapsulate(iph, skb);
+		skb->rxhash = 0;
 		netif_rx(skb);
 		rcu_read_unlock();
 		return 0;