Hi Jiayu, > -----Original Message----- > From: Hu, Jiayu > Sent: Thursday, June 22, 2017 4:18 PM > To: Tan, Jianfeng > Cc: dev@dpdk.org; Ananyev, Konstantin; y...@fridaylinux.org; Wiles, Keith; > Bie, Tiwei; Yao, Lei A > Subject: Re: [PATCH v5 2/3] lib/gro: add TCP/IPv4 GRO support > > On Mon, Jun 19, 2017 at 11:43:20PM +0800, Tan, Jianfeng wrote: > > > > > > On 6/18/2017 3:21 PM, Jiayu Hu wrote: > > > > > > Each element in the flow array records the information of one flow, > > > which includes two parts: > > > - key: the criteria of the same flow. If packets have the same key > > > value, they belong to the same flow. > > > - start_index: the index of the first incoming packet of this flow in > > > the item array. With start_index, we can locate the first incoming > > > packet of this flow. > > > Each element in the item array records one packet information. It mainly > > > includes two parts: > > > - pkt: packet address > > > - next_pkt_index: index of the next packet of the same flow in the item > > > array. All packets of the same flow are chained by next_pkt_index. > > > With next_pkt_index, we can locate all packets of the same flow > > > one by one. > > > > > > To process an incoming packet, we need three steps: > > > a. check if the packet should be processed. Packets with the following > > > properties won't be processed: > > > - packets without data; > > > - packets with wrong checksums; > > > > Why do we care to check this kind of error? Can we just suppose the > > applications have already dropped the packets with wrong cksum? > > > > > - fragmented packets. > > > > IP fragmented? I don't think we need to check it here either. It's the > > application's responsibility to call librte_ip_frag firstly to reassemble > > IP-fragmented packets, and then call this gro library to merge TCP packets. > > And this procedure should be shown in an example for other users to refer. > > If we leave this check to applications, they have to call librte_ip_frag > first, then call GRO library. If they call GRO library first, error > happens. But if GRO checks if the packet is fragmented, no error happens. > IMO, it's more flexible. Besides, for GRO library, to check if the packet > is fragmented is very simple. Just to check if DF bit is set is enough. > So I still think GRO library need to check it.
I would expect ip fragment is also a gro engine (might be two for ipv4 and ipv6).
