adding filtering example to trace.py help
diff --git a/tools/trace.py b/tools/trace.py
index a56a691..71688fb 100755
--- a/tools/trace.py
+++ b/tools/trace.py
@@ -602,6 +602,10 @@
in kernel/sched/sched.h which is in kernel source tree and not in kernel-devel
package. So this command needs to run at the kernel source tree root directory
so that the added header file can be found by the compiler.
+trace -I 'net/sock.h' \\
+ 'udpv6_sendmsg(struct sock *sk) (sk->sk_dport == 13568)'
+ Trace udpv6 sendmsg calls only if socket's destination port is equal
+ to 53 (DNS; 13568 in big endian order)
"""
def __init__(self):