xref: /src/external/cddl/dtracetoolkit/dist/Docs/Examples/weblatency_example.txt

The following is a demonstration of the weblatency.d script.

Here we run weblatency.d while a mozilla browser loads the 
http://www.planetsolaris.org website. After the website was loaded, Ctrl-C
was hit to print the following report,

   # weblatency.d
   Tracing... Hit Ctrl-C to end.
   ^C
   HOST                                     NUM
   static.flickr.com                          1
   images.pegasosppc.com                      1
   www.planetsolaris.org                      5
   blogs.sun.com                              7
   
   HOST                             AVGTIME(ms)
   static.flickr.com                         65
   blogs.sun.com                            285
   images.pegasosppc.com                    491
   www.planetsolaris.org                    757
   
   HOST                             MAXTIME(ms)
   static.flickr.com                         65
   images.pegasosppc.com                    491
   blogs.sun.com                            962
   www.planetsolaris.org                   3689

This gives us an understanding on which hosts were responsible for the 
time endured while loading the website. It turns out that requests to
www.planetsolaris.org were the slowest, with a maximum time of 3.7 seconds
(probably the first request, which incurred a DNS lookup).



The following shows the same google lookup performed on a number of sites,

   # weblatency.d
   Tracing... Hit Ctrl-C to end.
   ^C
   HOST                                     NUM
   www.google.com.au                          3
   www.google.co.uk                           3
   www.google.com                             3
   www.google.co.nz                           3
   
   HOST                             AVGTIME(ms)
   www.google.co.nz                         450
   www.google.com.au                        502
   www.google.com                           567
   www.google.co.uk                         595
   
   HOST                             MAXTIME(ms)
   www.google.co.nz                         544
   www.google.com.au                        559
   www.google.com                           744
   www.google.co.uk                         763

From the average time you would guess that I was running this from 
New Zealand (the fastest), with times to the other hosts following suit
(Australia, USA, UK). I was actually running this from Australia - it's
interesting that the New Zealand server responded slightly faster.




Now several websites are loaded as a larger demonstration,

   # weblatency.d
   Tracing... Hit Ctrl-C to end.
   ^C
   HOST                                     NUM
   shop.abc.net.au                            1
   static.technorati.com                      1
   sunopensolaris.112.2o7.net                 1
   www.theage.com.au                          1
   ffxcam.smh.com.au                          1
   sunglobal.112.2o7.net                      2
   embed.technorati.com                       2
   technorati.com                             2
   fdimages.fairfax.com.au                    4
   blogs.sun.com                              5
   bugs.opensolaris.org                       7
   www.abc.net.au                            34
   www.smh.com.au                            51
   
   HOST                             AVGTIME(ms)
   ffxcam.smh.com.au                          0
   sunglobal.112.2o7.net                      0
   www.abc.net.au                            56
   www.theage.com.au                         64
   shop.abc.net.au                           65
   www.smh.com.au                            73
   fdimages.fairfax.com.au                   88
   blogs.sun.com                            130
   bugs.opensolaris.org                     162
   static.technorati.com                    350
   technorati.com                           352
   embed.technorati.com                     632
   sunopensolaris.112.2o7.net               900
   
   HOST                             MAXTIME(ms)
   ffxcam.smh.com.au                          0
   sunglobal.112.2o7.net                      0
   www.theage.com.au                         64
   shop.abc.net.au                           65
   fdimages.fairfax.com.au                  243
   www.smh.com.au                           244
   blogs.sun.com                            293
   www.abc.net.au                           315
   static.technorati.com                    350
   technorati.com                           356
   bugs.opensolaris.org                     560
   sunopensolaris.112.2o7.net               900
   embed.technorati.com                     973

It's interesting that the most common host (www.smh.com.au, NUM == 51),
responded with a fast AVGTIME (73 ms). The reason for this may be due to
cacheing by my proxy server. Less common hosts such as embed.technorati.com
were quite slow.



The results from weblatency.d are interesting, but they don't point the
finger at one single cause for website latency. The value here is the response
time experienced by the client - which is a combination of many response 
times (link speeds, proxy server, DNS server, web server).