script examples network profiling examples of SystemTap scripts network profiling network profiling examples of SystemTap scripts probably http://sourceware.org/systemtap/examples/network/nettop.stp profiling the network examples of SystemTap scripts network traffic, monitoring examples of SystemTap scripts tracepoint The network stack in Linux can discard packets for various reasons. Some Linux kernels include a tracepoint, kernel.trace("kfree_skb"), which easily tracks where packets are discarded. uses kernel.trace("kfree_skb") to trace packet discards; the script summarizes which locations discard packets every five-second interval. The kernel.trace("kfree_skb") traces which places in the kernel drop network packets. The kernel.trace("kfree_skb") has two arguments: a pointer to the buffer being freed ($skb) and the location in kernel code the buffer is being freed ($location). Running the dropwatch.stp script 15 seconds would result in output similar in . The output lists the number of misses for tracepoint address and the actual address. Monitoring for dropped packets 51 packets dropped at location 0xffffffff8024cd0f 2 packets dropped at location 0xffffffff8044b472 51 packets dropped at location 0xffffffff8024cd0f 1 packets dropped at location 0xffffffff8044b472 97 packets dropped at location 0xffffffff8024cd0f 1 packets dropped at location 0xffffffff8044b472 Stopping dropped packet monitor To make the location of packet drops more meaningful, refer to the /boot/System.map-`uname -r` file. This file lists the starting addresses for each function, allowing you to map the addresses in the output of to a specific function name. Given the following snippet of the /boot/System.map-`uname -r` file, the address 0xffffffff8024cd0f maps to the function unix_stream_recvmsg and the address 0xffffffff8044b472 maps to the function arp_rcv: [...] ffffffff8024c5cd T unlock_new_inode ffffffff8024c5da t unix_stream_sendmsg ffffffff8024c920 t unix_stream_recvmsg ffffffff8024cea1 t udp_v4_lookup_longway [...] ffffffff8044addc t arp_process ffffffff8044b360 t arp_rcv ffffffff8044b487 t parp_redo ffffffff8044b48c t arp_solicit [...]