Hi! On 19:45 Sat 15 Oct , amit mehta wrote: ... > Now in step 4 above, driver passes this packet to the > network layer by calling netif_receive_skb() which may return > NET_RX_DROP (packet was dropped), but most > (I checked some of the network driver code) of the network > drivers do not do this check. > Hence, > Q1: Shouldn't drivers be doing that ? The return value NET_RX_DROP seems to be used in various places where no congestion exists: http://lxr.linux.no/linux+v3.0.4/net/ipv4/ip_forward.c#L131 http://lxr.linux.no/linux+v3.0.4/net/ipv4/ip_input.c#L369 http://lxr.linux.no/linux+v3.0.4/net/ipv4/ip_input.c#L451 What should network drivers do with this info? Also, there might be multiple layer 3 protocols. If one of them would signal congestion, should the driver slow down receiving? Maybe the question is rather why does this variable exist at all. I guess it is just to got statistic data. > Q2: Suppose the Card keeps pushing the frames at very high rate > (10 Gig adapters are already in the market and maybe in near future > we might have even faster ethernet adapters) then how the driver > and the networking stack will handle such rapid frames arrivals? > Will NAPI, interrupt coalescing be enough ? It seems like net_rx_action does some throttling: http://lxr.linux.no/linux+v3.0.4/net/core/dev.c#L3764 -Michi -- programing a layer 3+4 network protocol for mesh networks see http://michaelblizek.twilightparadox.com _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
