From Earlham Cluster Department
1. Timer location: net/socket.c:1551, sys_send. Data is copied from user to kernel space via copy_from_user.
2. Timer location: net/ipv4/af_inet.c:661, inet_sendmsg. Kernel buffer is wrapped into a BSD socket data structure.
3. Timer location: net/ipv4/tcp_output.c:374, tcp_transmit_skb. TCP wrapper placed around data.
4. Timer location: net/ipv4/ip_output.c:240, ip_finish_output. IP wrapper placed around data.
5. Timer location: net/ipv4/ip_output.c:224, tp_hard_start_xmit. Data is copied from kernel memory to card memory and transmitted over the line. This begins in hard_start_xmit, which is a function defined by the driver.
6. Timer location: net/core/dev.c:1843,1849, process_backlog. Data is taken from line to card memory by driver then copied from card memorty to kernel memory via skb buffer dequeuing (skb_dequeue).
7. Timer location: net/ipv4/ip_input.c:293, ip_rcv_finish.
8. Timer location: net/ipv4/tcp_ipv4.c:1744, tcp_v4_rcv.
9. Timer location: net/ipv4/tcp_input.c:4362,4398,4449, tcp_rcv_established.
10. Timer location: net/socket.c:1601, sys_recvfrom.