1Demonstrations of gethostlatency, the Linux eBPF/bcc version. 2 3 4This traces host name lookup calls (getaddrinfo(), gethostbyname(), and 5gethostbyname2()), and shows the PID and command performing the lookup, the 6latency (duration) of the call in milliseconds, and the host string: 7 8# ./gethostlatency 9TIME PID COMM LATms HOST 1006:10:24 28011 wget 90.00 www.iovisor.org 1106:10:28 28127 wget 0.00 www.iovisor.org 1206:10:41 28404 wget 9.00 www.netflix.com 1306:10:48 28544 curl 35.00 www.netflix.com.au 1406:11:10 29054 curl 31.00 www.plumgrid.com 1506:11:16 29195 curl 3.00 www.facebook.com 1606:11:25 29404 curl 72.00 foo 1706:11:28 29475 curl 1.00 foo 18 19In this example, the first call to lookup "www.iovisor.org" took 90 ms, and 20the second took 0 ms (cached). The slowest call in this example was to "foo", 21which was an unsuccessful lookup. 22 23 24USAGE message: 25 26# ./gethostlatency -h 27usage: gethostlatency [-h] [-p PID] 28 29Show latency for getaddrinfo/gethostbyname[2] calls 30 31optional arguments: 32 -h, --help show this help message and exit 33 -p PID, --pid PID trace this PID only 34 35examples: 36 ./gethostlatency # trace all TCP accept()s 37 ./gethostlatency -p 181 # only trace PID 181 38