On receving side upto tcp layer skb->len=1480 now where is packet assembled on tcp layer ? or it is directly copies into user space buffer.
I am sending len = 10000 in send system call. On Mon, Jun 3, 2013 at 9:45 PM, Craig Jackson <cjack...@ebscohost.com>wrote: > In my experience, the second paragraph isn't quite true. What you see with > TSO is the pre-segmentation "packet", up to 65k. (By this I mean the set of > data which is given to the offload hardware to segment.) So you need to > make sure that your "-s" value is big enough to see everything. > > (Speaking as someone who was bitten by bugs in the early versions of TSO.) > > Craig > > -----Original Message----- > From: kernelnewbies-bounces+cjackson=ebscohost....@kernelnewbies.org[mailto: > kernelnewbies-bounces+cjackson=ebscohost....@kernelnewbies.org] On Behalf > Of valdis.kletni...@vt.edu > Sent: Monday, June 03, 2013 12:03 PM > To: Varun Sharma > Cc: kernelnewbies@kernelnewbies.org > Subject: Re: assembly of packets > > On Mon, 03 Jun 2013 14:48:41 +0530, Varun Sharma said: > > > If TSO(tcp segmentation offload ) is enabled then nic card handle > > segmentation then where is assembly of packets happens ? Is it > > tcp_rcv_established function ? > > The whole *point* of TSO is so the NIC does all the segmentation > reassembly and DMA, and wake the kernel up when all the data is already > stashed in buffers fully processed. > > Incidentally, this is why if you run tcpdump on an interface that has TSO > enabled, you'll only see the first 3 handshaking packets and the final FIN > packets - the other packets wake up the TCP stack at a point after where > tcpdump's tap would have seen the packet. >
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